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The European Journal of Plant Science and Biotechnology ©2010 Global Science Books

Origin, Geographical Distribution and Phylogenic Relationships

of Common Buckwheat (Fagopyrum esculentum Moench.)

István Gondola1* • Peter P. Papp2

1 Research Institute of Nyíregyháza, University of Debrecen, Centre for Agricultural and Applied Economic Sciences, Nyíregyháza, Westsik Vilmos 4/6, 4400 Hungary
2 Agricultural Biotechnology Center, Szent-Györgyi A. 4. Gödöllő, 2100 Hungary

Corresponding author: * gondolai@nykk.date.hu

ABSTRACT
Fagopyrum is a genus of about 15 species, most of them indigenous to temperate eastern Asia. Common buckwheat (Fagopyrum
esculentum Moench), the most important species in the genus, has been extensively grown in the northern hemisphere, from Eastern
Europe through Japan and in the Americas, as a low-input subsistence or cash crop. It is a diploid species with an indeterminate growth
habit. Flowers are hermaphroditic, heteromorphic and self-incompatible. The floury grain is used as a cereal. Cultivation goes back to the
distant past. According to archaeological data and written historical records, ancient civilizations in China and Japan used buckwheat as a
staple food. This review discusses the origin and worldwide distribution of common buckwheat and some of the related plant species,
using molecular genetic methods including studies of isozyme variability and modern DNA analysis. The following fields of interest are
covered: botanical and genetic characteristics of common buckwheat with special regard to the heterostylic flower morphology, original
birthplace, geographical distribution, diffusion of cultivation to new geographical areas, genetic relationships among remote populations,
phylogenic relations of wild and cultivated Fagopyrum species. Botanical description and illustration of some Fagopyrum species are also
presented. Studies concerning phylogenic relationships of species within the genus Fagopyrum were surveyed and discussed by reviewing
the methods used to obtain primary data. The current view, emerging from them, is presented by naming those clades identified in the
majority of the studies.

Keywords: cymosum group, domestication, heteromorphic flower morphology, molecular methods, self-incompatibility, urophyllum
group, wild ancestor

CONTENTS

INTRODUCTION .............................................................................................................................................................................. 17
TAXONOMICAL POSITION AND BOTANICAL DESCRIPTION OF THE GENUS FAGOPYRUM ................................................. 18
ORIGIN AND DISTRIBUTION OF COMMON BUCKWHEAT AND RELATED SPECIES .............................................................. 21
Centre of origin .............................................................................................................................................................................. 21
Diffusion routes on the studies of allozyme variability ..................................................................................................................... 22
Diffusion routes on the studies of DNA-based markers .................................................................................................................... 24
ORIGINAL BIRTHPLACE OF CULTIVATED COMMON BUCKWHEAT ....................................................................................... 24
WILD FAGOPYRUM SPECIES. ......................................................................................................................................................... 25
PHYLOGENIC RELATIONSHIPS OF FAGOPYRUM SPECIES. ....................................................................................................... 26
Methods of phylogenic studies ........................................................................................................................................................ 26
Results of phylogenic studies ........................................................................................................................................................... 27
BOTANICAL DESCRIPTION OF SOME SELECTED FAGOPYRUM SPECIES WITH BOTANICAL NAMES AND SYNONYMS ... 28
Cymosum group ............................................................................................................................................................................. 28
Urophyllum group .......................................................................................................................................................................... 29
FUTURE PERSPECTIVES ................................................................................................................................................................ 30
REFERENCES. .................................................................................................................................................................................. 30

INTRODUCTION pseudocereal.
Although the genus Fagopyrum comprises several spe-
Buckwheat is a temperate zone plant used for human cies, only two of them are of notable economic importance,
nutrition since prehistoric times. It is a fast-growing annual these are the common (also named sweet) buckwheat (F.
plant with a variety of potential uses. The floury grain of esculentum Moench) and tartary (also named bitter) buck-
buckwheat is used in a way similar to the grains of cereals, wheat (F. tataricum Gaertn.), both with numerous varieties
despite that botanically buckwheat is not a member of the and landraces in commercial production. Globally, common
family Gramineae or Poaceae (“Grass” family). Buckwheat buckwheat is far more important than tartary buckwheat,
is a dicotyledonous broadleaved plant, belonging to the estimated on the smaller number of countries where this
family Polygonaceae, the “smartweed” family, also called latter species is grown (mainly in the mountainous regions
“knotweed” family or “buckwheat” family. For this reason of China, Bhutan, Nepal and Northern India).
the seed of buckwheat is rather a fruit than a grain (the Buckwheat has been extensively grown in the northern
botanical term is “achene”). It is often referred to as a hemisphere, from Eastern Europe through Japan, as a low-

Received: 29 April, 2009. Accepted: 26 March, 2010.

Invited Review
 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

input subsistence or cash crop. It is also grown in the Ame- ional Genetic Resources Program).
ricas. It performs best in temperate or subtropical climate if Scientific name of buckwheat comes from the Latin
the rainfall is reliable during the growing season. It may be fagus (beech) and the Greek pyrus (wheat), resulting from
grown successfully at higher elevations in the tropics (Jan- the resemblance of the achene to a beech-nut and from the
sen 2006). Buckwheat is adapted to poor lands. It does well fact that it is used like wheat (Flora of North America 5.31).
on soils where most of the important cereals fail. At present The word esculentum is of Latin origin and means edible
the crop is hardly affected by diseases and pests, which, (Dictionary of Botanical Epithets). Similarly, the English
together with the short growing period and the low require- word “buckwheat” refers to beech-nut and wheat, being of
ments for management, offers a great potential for both Dutch origin (Online Etymology Dictionary). Synonyms in
organic and conventional buckwheat production. various European languages are: French wheat; saracen
Total world production of buckwheat seed in 2008 was corn; beechwheat (English); blé noir; sarrasin (French);
estimated to be 1.92 million tons from 2.46 million ha. This buchweizen; heidekorn (German); poganka (Polish); pohán-
amount is about 25 to 30% down as compared to the amount ka; hajdina; tatárka (Hungarian); grano saraceno (Italian);
produced 5 to 10 years earlier, and has not essentially ajda (Slovenian); boekweit (Dutch); viljatatar (Finnish);
changed since 2005 (FAOSTAT 2009). The main producers grechikha posevnaia (Russian); grano turco, trigo sarraceno
in 2008 were the Russian Federation (0.92 million tons), (Spanish); navadna ajda (Croatian); bokhvete, bokkveite
China (0.33 million tons), Ukraine (0.24 million tons) and (Norwegian) (Porcher 1995).
France (0.12 million tons). Beside the above, Poland, At present it is thought that there are about 15 species
Kazakhstan, Brazil and Japan also grow significant quanti- and numerous subspecies, ecotypes comprised in the genus
ties of buckwheat. The grain is mainly used locally. Total Fagopyrum, which implies a great genetic diversity. Accor-
world export of buckwheat was only 0.14 million tons in ding to the description in Flora of North America (5.31)
2007, with China as the main exporting and Japan as the they are mostly annual, taprooted herbs with erect or ascen-
main importing countries (0.09 and 0.07 million tons, res- ding stems, glabrous or puberulous. The leaves are decidu-
pectively). ous, cauline, alternate, petiolate (proximal leaves) or sessile
The objective of this compilation is to review the pre- (distal leaves). The ocrea is persistent or deciduous, charta-
sent knowledge on the origin, geographical distribution and ceous, with the petiole base articulated. The blade is cordate,
the taxonomy of cultivated buckwheat and the related spe- triangular, hastate, or sagittate, with the margins entire to
cies, based on the documented literature. The review is not sinuate. Pedicels present. Inflorescences are axillary, or ter-
intended to be exhaustive. minal and axillary, raceme- or panicle-like, pedunculate.
Fagopyrum is a genus of about 15 species, most of Flowers are bisexual or, rarely, bisexual and staminate on
them indigenous to eastern Asia. The species are of dif- the same plant, 2-6 per ocreate fascile, heterostylous or
ferent ploidy levels, and represent two types of breeding homostylous, base stipe-like. The perianth is nonaccrescent,
system, self-compatibility and self-incompatibility, with the white, pale pink, or green, broadly campanulate, glabrous;
economically most important species, F. esculentum being The tepals are 5, distinct, petaloid, dimorphic, with the
self-incompatible. Domesticated species are mainly culti- outer ones smaller than the inner ones. Stamens are 8, with
vated in temperate and subtropical areas. distinct, free and glabrous filaments. The anthers are white,
pink, or red, oval to elliptic. The 3 styles are reflexed, dis-
TAXONOMICAL POSITION AND BOTANICAL tinct, with the stigmas capitate. The achenes are strongly
DESCRIPTION OF THE GENUS FAGOPYRUM exserted, brown to dark brown or gray, sometimes mottled
black, unwinged or essentially so, bluntly to sharply 3-
The parentage of the genus Fagopyrum with that of com- gonous, glabrous. Seeds: embryo folded, x = 8.
mon buckwheat is shown in the taxonomic tree below Knowledge was obscure on the genetic relationships
(Encyclopaedia Britannica). among species within the genus Fagopyrum until the 1980s.
 Kingdom: Plantae Perennial buckwheat [F. cymosum (Trev.) Meisn] was con-
 Phylum (Division): Magnoliophyta (Flowering plants) sidered for long to be the putative wild ancestor of common
 Class: Magnoliopsida (Dicotyledons) buckwheat (Campbell 1976; Nagatomo 1984 cited in Ohni-
 Order: Caryophyllales shi 1990). Research conducted during the past 20 years,
 Family: Polygonaceae coupled with the discovery of several new species, has
 Genus: Fagopyrum provided new data on the origin, geographical distribution
 Specific epithet: esculentum (Moench 1794) and the level of speciation, and has also revealed great part
 Binomial (botanical) name: Fagopyrum esculentum of the species relationships. Earlier phylogenic studies were
Moench (also named, according to the earlier classification: using morphological characters and izozyme markers. The
Polygonum fagopyrum L.) development of the currently used, DNA-based molecular
The family Polygonaceae comprises about 50 genera markers has provided a highly efficient tool to examine
and more than 1100 species of herbs (commonly), shrubs genetic relationships within the genus.
and small trees (Flora of North America 5.44). Numerically Common buckwheat (Fagopyrum esculentum Moench)
the most important genera are Eriogonum (250 species), is a heterostylous diploid species with an indeterminate
Polygonum (200 species), Rumex (200 species), Coccoloba growth habit. It is an annual broadleaved plant, with a
(120 species) and Calligonum (80 species). Some well- smooth, succulent stalk, a knotted single main stem that
known members include Rumex (sorrel), Rheum (rhubarb), develops lateral branches (Fig. 1). Generally, in a field popu-
Polygonum (knotgrass) and Fagopyrum (buckwheat), with lation the plants only develop primary branches. The main
sorrel and buckwheat as crops of economical importance. stem is grooved, generally green, but sometimes tinged with
Many common and noxious weeds are found within this red. Plant height varies from 30 to as much as 120 cm or
family. The family is present worldwide, with a few species more. The stems are more or less round and hollow, with a
in the tropics and the greatest biodiversity in the northern diameter of 3 to 15 mm. At the time of maturity the stems
temperate regions. “The family is named for the many and branches turn red. The plants have a short taproot,
swollen node joints that some species have; poly means penetrating to a depth of 30 to 50 cm in the soil, with fine
many and goni means knee or joint” (Serving History). lateral roots spreading to a width of 25 to 30 cm. Root
Buckwheat refers to several genera of the family Poly- architectural characteristics give buckwheat a relatively
gonaceae: the genus Eriogonum is native to North America, shallow rooting habit. The leaves are petiolate, positioned
and is not closely related to the Eurasian genus Fagopyrum alternately on the opposite sides of the stem, heart shaped,
(Flora of North America 5.1). The agricultural weed “wild ovate-triangular to triangular, 4 to 8 cm long. The blades are
buckwheat” syn. “climbing buckwheat” (Polygonum con- glabrous (hairless) (Flora of North America 5.1; Campbell
volvulus L. syn. Fallopia convolvulus L.) is also in the same 1997; Lazányi 1999; Gocs 2002; Jansen 2006).
family, but belongs to genus Fallopia (USDA, ARS, Nat- The flowers grow terminal, densely clustered in

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 Origin and distribution of buckwheat. Gondola and Papp

tepal

style with stigma

anther

filament

pedicel

Fig. 1 A stand of buckwheat (F. esculentum Moench, cv. ‘Hajnalka’) Fig. 3 Structure of pin type flower of common buckwheat (Fagopyrum
near Nagykálló (North East Hungary) in 2008. (Source: I. Gondola) esculentum Moench.). (Source: I. Gondola)

anther

filament

style with stigma

tepal

pedicel
Fig. 2 Flowers of common buckwheat (F. esculentum Moench, cv.
‘Hajnalka’) near Nagykálló (North East Hungary) in 2008. (Source: I.
Gondola)
Fig. 4 Structure of thrum type flower of common buckwheat (Fago-
pyrum esculentum Moench.). (Source: I. Gondola)

racemes, light fresh in colour, and perfumed (Fig. 2). The

sepals are usually white, pink or dark pink. Flowers are her-
maphroditic and heteromorphic, i.e. two types of flowers
are produced on separate plants (Campbell 1997).
“The existence of variation in floral structure within the
same species was detected by several authors, but it was not
until the publication of Hildebrand’s studies in 1867 and a
subsequent publication of Darwin’s observations in 1877
(see Vuilleumier 1967 for review and detailed references)
that a casual relation between floral variations and the pre-
vention of self-fertilization was fully appreciated” (Frankel
and Galun 1977).
In Fagopyrum, the heteromorphic flower morphology is
associated with self-incompatibility, with the exception of
three species, namely F. pleioramosum, F. macrocarpum
and F. callianthum, which are heterostylous and self-com-
patible (Ohsako and Ohnishi 2000). “Heteromorphic incom-
patibility was reported in several ornamental plants, and is
very rare in economic crops” (Frankel and Galun 1977). In
buckwheat, heteromorphism is manifested in stylar length Fig. 5 Ripening fruits of common buckwheat (F. esculentum Moench,
and therefore the term heterostyly is preferred to heteromor- cv. ‘Hajnalka’) near Nagykálló (North East Hungary) in 2008.
phism. Common buckwheat, a distylous species, is com- (Source: I. Gondola)
posed of two types of plants. The pin flower has long styles
with short stamens, whereas the thrum flower is of the
opposite arrangement (Campbell 1997). The floral structure pollination infertile (Frankel and Galun 1977). Fertilization
for the pin type is shown in Fig. 3 and for the thrum type is can only take place between pin and thrum types of flowers.
shown in Fig. 4. Heteromorphic incompatibility renders This complex of floral mechanism is governed by a
both self-pollination and intramorph (illegitimate) cross- single locus which also regulates the incompatibility rela-

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 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

tion (Bodmer 1966; Frankel and Galun 1977). The inability was grown hundreds of years ago, with yield levels prac-
of selfing is explained with pollen incompatibility between tically unchanged.
the two types rather than with the heterostylic architexture Some of the problems that are frequently encountered in
of the flowers (de Nettancourt 1977; Wang et al. 2005b). the production of common buckwheat can only be solved
Two sizes of pollen are associated with the heteromorphic with genetic improvement. Examples of these are:
system in common buckwheat. Large pollen grains approxi-  lack of frost tolerance (Kalinová and Moudry 2003;
mately 0.16 mm in diameter are produced by thrum flowers Jansen 2006),
while pin flowers produce smaller pollen grains that are ap-  shattering of seeds (Campbell 1997; Wang et al. 2005a)
proximately 0.10 mm in diameter (Campbell 1997). Hirose  lack of resistance to lodging (Campbell 1997; Jansen
et al. (1994) reported that pollen tube in intramorphic polli- 2006),
nation in heterostylous Fagopyrum species was inhibited at  indeterminate growth habit (Ohnishi 1993c; Kreft 1998),
the stigma or style, and was shorter than that in intermor-  low rate of seed-set (in cross-pollinated flowers). Lack
phic pollination within the same species. of fertilization was the major cause of low seed set,
Heterostyly has sporadically evolved in various phylo- rather than abortion of the embryo, in the study of Tay-
genic taxa. It can be hypothesized that the genus Fago- lor and Obendorf (2001).
pyrum is entirely heterostylous. The non-heterostylous spe- Because of open pollination, populations of common
cies (F. tataricum and F. gracilipes) might have arisen from buckwheat are highly heterozygous and heterogeneous. Fin-
the heterostylous species by the loss of heterostyly and ding recessive genes for certain valuable traits (e.g. deter-
simultaneous development of self-fertilizing mechanisms minate growth) is a general objective of buckwheat breed-
(Ohnishi 1989). ers. Selection for these traits is difficult, because recessive
Due to heterostyly and open pollination by insects, seed genes are often hidden by out-crossing and are covered by
set is generally low in common buckwheat. Buckwheat dominant alleles (Kreft et al. 2007).
flower is very attractive to bees that use the nectar to pro- Genetic improvement of buckwheat is treated in detail
duce a specially flavoured, dark honey (Campbell 1997). in the comprehensive work by Campbell (1997).
The nut (so-called 'seed') has a dark brown, tough rind, The transfer of the self-pollinating mechanism to com-
enclosing the kernel or seed, and is three-sided in form, mon buckwheat would be of particular importance, since
with sharp angles (Fig. 5). this would reduce dependence on insect pollination, allow
As for the ploidy level, common buckwheat is a diploid for increased rate of seedset which, in turn, might result in
plant with a chromosome number of 2n = 2x = 16 (Darling- higher yields. Successful attempts have been made through
ton and Janaki Ammal 1945). hybridizing with the closely related wild species F. homo-
Buckwheat is a multi-purpose crop, for nearly all parts tropicum at the diploid level.
of the plant are used in a large variety of ways. The leaf The single gene complex that controls self-incompati-
provides rutin (vitamin-P), a pharmaceutical product. As a bility and flower morphology segregates as a simple Men-
rutin – containing plant buckwheat, also named Fagopyri delian factor, with two allelic states, S and s, which control
herba, has traditionally been used to brew tea to treat hyper- the thrum (Ss) and the pin (ss) forms (Garber and Quinsen-
tonia. The flower produces nectar for honey-bees. Buck- berry 1927; Matsui et al. 2003). The pattern of segregation
wheat has many uses in cooking. The dehulled grains are is shown in Fig. 6.
eaten boiled. Flour can be made from the grain either entire Matsui et al. (2003) reported that Sharma and Boyes
or dehulled. The flour is prepared in various ways to make (1961) regarded this gene as the S supergene proposed for
bread, pancakes and other traditional foods as well as spe- Primula (Dowrick 1956). They postulated that the S super-
cial diets. Beer is brewed from the grain, and the grain is gene of buckwheat consists of five genes: G, style length; IS,
also distilled into spirits. Buckwheat hulls are used as stylar incompatibility; IP pollen incompatibility; P, pollen
filling for a variety of upholstered goods, including pillows. size; A, anther height. Pin has small pollen and thrum has
The straw makes good livestock feed. As a fast growing larger pollen. Pin-linked characters are recessive, and thrum-
plant, buckwheat also makes good green manure even in linked characters are dominant. The genotype of pin is
cases when the gap period between two main crops is short giSiPpa/giSiPpa, and that for thrum is GISIPPA/giSiPpa.
(Edwardson 1996; Ihme et al. 1996; Campbell 1997; Jansen Self-compatible buckwheat lines were produced by an
2006; Brunori and Végvári 2007; Christa and Soral-Smie- interspecific cross between F. esculentum and a closely
tana 2008). related self-fertile, homostylous wild relative, F. homotro-
Buckwheat is neglected and underutilized at present, picum with embrio rescue (Campbell 1995; Aii et al. 1998;
both as a nutritious food and as a viable alternative crop Woo et al. 1999; Matsui et al. 2003). The flower mor-
plant, particularly in the developed countries (Campbell phology of the self-compatible lines is long homostyle and
1997). In contrast with the important cereal crop species, is controlled by a single gene. The allele controlling homo-
only little crop improvement efforts have been focused on morphic flowers was designated as Sh, and the dominance
buckwheat during the past few decades. Today buckwheat relationship of Sh with S and s was found to be S > Sh > s
is still mostly grown as a primitive crop, in a similar way it (Woo et al. 1999). The Sh allele was produced by recombi-

Fig. 6 Mendelian segregation of the single gene complex that controls self-incompatibility and heterostylous flower morphology in common
buckwheat (Fagopyrum esculentum Moench). (Source: I. Gondola)

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 Origin and distribution of buckwheat. Gondola and Papp

nation between iS and iP in the supergene. By studying A case study on Yunnan, South West China in 2001
segregation in the F2 and BC generations, it was suggested (Chen and Dao 2001), listed nine wild species of Fago-
that the self-compatible line possesses the pin type of stylar pyrum as endemic to this province, each species given a
incompatibility, and thrum type of pollen incompatibility vernacular name: golden Fagopyrum (F. cymosum), rock
genes (Matsui et al. 2003). The self-compatible, long homo- Fagopyrum (F. gilesii), thin cauli wild Fagopyrum (F. gra-
stylous genotype was suggested to be giSIPPA/giSIPPA (ShSh). cilipes), tooth-alar wild Fagopyrum (F. gracilipes var. odon-
Wang et al. (2005b) proposed that homostyly and self- topterum), small wild Fagopyrum (F. leptopodum), sparse
compatibility is controlled by a two-gene model in F. homo- stachys small Fagopyrum (F. leptopodum var. grossii),
tropicum and in the segregating progenies derived from linear leaf wild Fagopyrum (F. lineare), bolting Fagopyrum
interspecific crosses between F. homotropicum and F. escu- (F. statice) and hard twig ten thousand-year Fagopyrum (F.
lentum. urophyllum).
The centres of origin can also be defined as the region
ORIGIN AND DISTRIBUTION OF COMMON where domestication of the particular plant first took place
BUCKWHEAT AND RELATED SPECIES and where the wild ancestor and the derived cultivated spe-
cies co-exist (De Candolle 1883; Molina-Cano et al. 1999).
Centre of origin Archaeological data and written historical records indi-
cate that buckwheat was extensively cultivated and used as
According to scientific evidence, the geographical areas a staple food by ancient Chinese as early as the 5 th-3rd cen-
where the ancestors of the presently cultivated plants once turies BC and thereafter (Li and Yang 1992), thus ancient
developed are, in many cases, located in the sunlit, dry (arid Chinese were the earliest nation to discover and utilize
or semi-arid) table-lands and highlands of mountain ranges. buckwheat. Not only was buckwheat cultivated, but it was
The same holds true for buckwheat. There is a general con- highly appreciated as a crop that contributed to overcome
sensus now among scientists that buckwheat is native to famine and disaster. The health protecting abilities of foods
temperate East Asia, more specifically to the eastern side of made of buckwheat were first recognized and documented
the Himalayas and South-West China (Campbell 1997; around 600 CE. According to Li and Yang (1992), Yunnan
Kreft 1998). The exact place of origin has been identified as province possesses 11 species of the genus, nearly three-
Yunnan province and the mountain area between Yunnan quarters of the total of 15 species known in the early 1990’s.
and Sichuan provinces (Ohnishi 1995). These are:
Vavilov, in his worldwide geographical survey, listed 1. Sweet (common) buckwheat (F. esculentum Moench
several centres of diversity (centres of origin), as sources of 1794)
genetic variation, each characteristic of a certain group of 2. Bitter buckwheat (F. tataricum Linn. ((Gaertner)) 1791)
domesticated crop plants (Vavilov 1926). Most of them are 3. F. cymosum (Trev) Meisn. 1832
located between 20 and 40° north latitude in Eurasia. China 4. F. gilesii (Hemsley) Hedberg 1946
is one of the eight centres of origin proposed by Vavilov, in 5. F. gracilipes (Hemsley) Dammer ex Diels (1918)
fact the largest one, as regards the number of species listed. 6. F. leptopodum (Diels) Hedberg (1944)
It was found later “that some species can indeed be said 7. F. grossii (Levl) H. Gross 1913 (Variant)
to have had a single and sudden origin localised and capa- 8. F. odontopterum Gross 1913 (Variant)
ble of being located. With others, however, the origin is not 9. F. lineare (Samuelss) Haraldson 1978
origin at all but a gradual transformation extending over 10. F. statice (Levl) H. Gross 1913
wide areas and long periods and shifting its focus in the 11. F. urophyllum (Bur. et Franch) H. Gross 1913.
course of time. Between the two extremes there is every Shapes of root systems for wild buckwheats can be clas-
gradation” (Darlington and Janaki Ammal 1945). sified into perennial globular or tuber root, and annual fib-
Research results obtained during the past two decades rous root. The cultivated species only develop fibrous root.
on the centre of origin of buckwheat, highlight Yunnan pro- Beside the occurrence of wild species in Yunnan, a great
vince of south-west China as a diversity hotspot for this variability also exists among accessions of cultivated com-
crop plant. This is the place where the highest diversity of mon buckwheat in morphological traits like colour and
endemic wild relatives of common buckwheat can be found architecture of flowers, fruit shape, fruit coat colour, and
today. Several species of the genus Fagopyrum can be length of growing period (Li and Yang 1992; Chen and Dao
found here forming a large pool of genetic diversity (Li and 2001).
Yang 1992; Ohnishi 1995). The region is dominated by The authors conclude that the typical evolutionary trend
rugged mountainous topography, climatic variability and a can be clearly detected based on shapes of Yunnan buck-
biologically diversified ecosystem (Chen and Dao 2001). wheat: perennial wild species → annual wild species →
Beside south-west China, common buckwheat is also annual cultivated species.
widely cultivated in mountainous regions of temperate Asia Cultivation of buckwheat was step by step spreading
in Nepal, India, China, and also in Japan and Korea. It is from the place of origin to other parts of the world: to South
also cultivated in the regions with cooler climate such as East Asia, India, Minor Asia in the 8th century, to Siberia
northern China. Cultivation of common buckwheat dates and Russia in the 13th century, to Europe in the 15th century,
back to the Jomon era (1000 BCE) in Japan, several hun- to the Americas in the 17th century, and later to Africa (Li
dred years BCE in northern China and more than 2000 and Yang 1992). An important part of the spread might have
years in eastern Tibet (Ohnishi 1985; Murai and Ohnishi occurred via transmission on the silk-road.
1995). The spread of buckwheat cultivation to European Despite that common buckwheat has been cultivated
countries is rather recent (Campbell 1976; Ohnishi 1985, since ancient times in several Asian countries including
1989). China, Korea and Japan, the place of origin and the process
Tartary buckwheat (F. tataricum), a homostylous, self of expansion of cultivation remained obscure for long.
fertilizing diploid species, with cleistogamous flowers (pol- Buckwheat was thought for a long time to have its
lination occurs before the flowers open), is the other domes- origin in northern China or the area of the river Amur (De
ticated food plant in the genus. Since this species carries a Candolle 1883; Ohnishi 1993b). In the late 19th century and
relatively high level of frost-tolerance, it is cultivated most in the first half of the 20th century, the discovery of a large
extensively in the Himalayan region of India, Nepal and number of wild relatives of common buckwheat by several
Bhutan, particularly in the areas of high altitude, 2000 m investigators in southern China suggested that the theory of
above see level and higher. It is one of the most important De Candolle on buckwheat’s origin in northern China or the
crops in these areas. Cultivation of tartary buckwheat is also area of the river Amur was false (Bretschneider 1898; Gross
of importance in southern China. In other places it is only 1913; Steward 1930; Ohnishi 1990).
occasionally cultivated. In many cases it is a weed in buck- All the written evidence we now have (geographical
wheat fields (Ohnishi 1989). distribution of Fagopyrum species, allozyme variability

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 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

between southern China and the Himalayan region) suggest Japanese and European populations was revealed to be less
that both common and tartary buckwheat were born in than the average of the annual plant species (Hamrick 1979;
southern China, and diffused westward along the southern Gottlieb 1981), and this was particularly true for the Euro-
slopes of the Himalayas together with two wild species also pean populations (Ohnishi 1983, 1985). Since buckwheat is
born in southern China (Ohnishi 1992). One of them is a completely outcrossing species due to heterostyly, and the
tetraploid perennial buckwheat (F. cymosum Meissn.) that usual population size is large, more than 104-106, we can
grows wild in temperate Himalayas and is commonly found expect a large amount of genetic variability in populations.
around habitation areas and farms. It is utilized in certain Therefore, there must be an explanation for the low allo-
regions as forage and also as a medicinal plant. This species zyme variability i.e. the loss of genetic variability in buck-
extends its distribution southward to the northern part of the wheat populations in Japan and Europe. A possible reason is
Indochinese Peninsula, southern part of China, and west- that populations in these regions may be considered to be
ward to the Himalayan region of Nepal and India as far as marginal populations that have lost several variant alleles
Karakoram and the Hindukush. It is also found in eastern during the spread of cultivation to these regions.
parts of Tibet (Ohnishi 1993a). The flowering pattern re- European common buckwheat populations came from
sembles that of F. esculentum in that both are heterostylous northern China long ago, based on allozyme analysis (Ohni-
outcrossing species and produce pin and thrum plants with shi 1986, 1993c). According to archaeological evidence (Li
white flowers. F. cymosum is, however, cytologically and and Yang 1992), buckwheat cultivation diffused to Europe
morphologically distinct and stands out as a separate taxon almost immediately after its spread from the place of birth
(Tahir and Farooq 1989). The other wild species born in in Yunnan province to northern China (2nd–1st centuries
southern China is F. gracilipes Hemsl., a self-fertilizing BCE), but cultivation only became popular in the Middle
tetraploid weedy plant in farmer’s fields. It is distributed Ages, in the 14th and 15th centuries and afterwards. Buck-
widely, covers almost the whole of China, except Tibet. wheat was first cultivated in Russia, Ukraine and Germany,
Bhutan is the western limit of its distribution. This species and from here it diffused southwards to the Mediterranean
is the most successful colonizer, and has the widest distri- region and further to the western part of Europe (Ohnishi
bution in China among Fagopyrum species (Ohnishi 1992). 1993c).
Most of the other wild Fagopyrum species have a narrow Within Europe, allozyme studies show greater genetic
endemic distribution in southern China. variability among samples from the northern regions (Rus-
An overview of buckwheat production and genetic sia, Poland, Hungary, Finland) than among samples from
diversity of Fagopyrum species in the Himalayan region is southern regions (Ohnishi 1993c). Further, a new morpholo-
given by Arora et al. (1995). The region includes the moun- gical variant is present in samples of southern European
tain ranges of Pakistan, India, Nepal and Bhutan. The area landraces, grey buckwheat with a grey husk rather than the
is very diverse in topography, climate and agro-ecology. usual brown husk. This variant is not present in the samples
Cultivation of buckwheat provides here a security for the of the silk-road. Another variant allele frequently found in
traditional subsistence farmers. Diverse ethnic communities southern Europe is the determinant inflorescence gene. This
grow this crop for grain and as a leafy vegetable, besides is a recessive gene also present in some Russian varieties,
using it as animal feed and as a medicine. The crop is well but apparently its frequency is much higher in southern
adapted to marginal lands and harsh environments and is Europe (Ohnishi 1993c).
cultivated under low input conditions. Common buckwheat Similar increase or decrease of allozyme frequency was
and tartary buckwheat are grown under diverse cropping observed by Ohnishi (1993c) at other loci of southern Euro-
patterns and cultural practices in different seasons, depen- pean populations, and also in populations from Kashmir,
ding on the climate and particularly the altitude. While India. As postulated by Ohnishi (1993c), the changes in
common buckwheat is adapted to both lowlands and up- genetic frequencies in these cases are probably due to ran-
lands and grows between 400-4200 m, tartary buckwheat is dom genetic drift during the course of diffusion, rather than
not grown in plains, and is confined to mid-hills and high- the systematic selection against particular alleles. Both the
hills. Companion crops on higher elevations are barley, western parts of India and southern Europe contain margi-
wheat, potato, amaranth, foxtail millet, proso millet and nal buckwheat populations, i.e. populations that are the
Brassiceae. Rice, soybean, finger millet and maize are the closest to the geographical terminus of the diffusion route.
rotating crops in the low hills and in the intermediate zone. In these populations random events such as founder and
Also, because of vertical crop zonation related to altitude, bottleneck effects might have taken place more frequently
common buckwheat is grown as a winter crop in plains, than elsewhere. Such events are less likely to occur in other
while tartary buckwheat is grown as a spring crop in mid- areas, where migration pressure from adjacent areas is
hills. Several hundreds of known landraces make a large strong enough to annihilate local differentiation of allele
diversity of the cultivated species, common buckwheat and frequencies. The same reasoning can be applied to explain
tartary buckwheat. They are maintained, characterised and the relatively low average heterozygocity and low percen-
evaluated in germplasm collections using some 30 descrip- tage of polymorphic loci in European populations, as found
tors, supported by international and national programs for by Ohnishi (1993c).
the conservation of plant genetic resources. Part of the land- Calculation of genetic distance in these studies with the
races is utilized in cultivation by native farmers and also in use of allele frequencies between populations revealed that
crop improvement programs by scientists. The Himalayan European populations are most closely related to the popu-
region is rich in genetic resources. Beside the two cultivated lations of the silk-road and to the Chinese populations and
species that have been grown here since the distant past, least related to the Kashmirian populations. The silk-road
numerous wild species also contribute to the genepool of populations, again, have almost the same genetic constitu-
Fagopyrum in the region. These are F. cymosum, F. graci- tion as Chinese populations. It follows from this, that Euro-
lipes and F. megacarpum, which are mainly perennial, late pean common buckwheat came from northern China through
maturing and indeterminate types. In contrast with earlier the silk road in very ancient times (1st or 2nd century or ear-
knowledge (Steward 1930) F. gilesii cannot be found in the lier). The introduction might have been repeated later, pos-
region of the northwestern Himalayas, it can only be found sibly also introducing tartary buckwheat as a weed, but the
in Yunnan province and eastern Tibet (Ohnishi 2001). buckwheat from the Himalayan region has never been intro-
duced into Europe. Migration pressure between the silk-
Diffusion routes on the studies of allozyme road and northern China is still acting, but European popu-
variability lations are isolated geographically from Asian populations
because the geographical gap between the Silk Road and
The diffusion routes of cultivated common buckwheat in Europe is great. After the introduction to Europe, local
Eurasia were followed by studying allozyme variability as a populations have changed considerably within a relatively
marker. The amount of allozyme variability in Korean, short period, i.e. the last 500 years (Ohnishi 1993c).

22
 Origin and distribution of buckwheat. Gondola and Papp

In the light of the above, there should be more allozyme larly the dry land does not allow the distribution of F. cymo-
variability within populations in southern China and the sum in this area.
Himalayan region, which are closer to, or are in fact, the A worldwide survey was conducted on allozyme varia-
centre of origin. bility in common buckwheat in the hope to find, as Vavilov
The gene frequencies at polymorphic loci did not vary proposed, a centre of allozyme diversity which might repre-
so much among the 15 Nepali populations but they were sent the original place of domestication of this crop (Ohni-
quite different from those in the two Kashmirian (Indian) shi 1993b). By comparing allozyme variability in cultivated
populations studied (Ohnishi 1985). There was no distinct populations from different parts of the world, the author
local differentiation in allozyme frequency among the popu- gave a clue to understand the genetic processes of domestic-
lations in Nepal, and the Nepali populations maintained as cation and subsequent diffusions of buckwheat to remote
much allozyme variability as other outcrossing annual plant geographical areas. The following conclusions were drawn
species. The two Kashmirian populations had almost the from the survey.
same genetic constitution, however, they showed several  At all loci, allele frequency does not vary much among
distinct characters from the Nepali populations. They were the populations from a wide range of Asian countries,
monomorphic at loci for which the Nepali populations were from Japan through Nepal. The large population size
polymorphic. The average genetic distance between the and the complete panmixis of each population by insect
Kashmirian populations and the Nepali populations was pollination may have led to the uniformity of gene fre-
0.0043, compared with genetic distance between the two quency among cultivated populations over wide areas in
Kashmirian populations of 0.00011, and the average of the Asia, along with enough migration among populations
distances between any two of the Nepali populations of (migration pressure nullifies the local differentiation of
0.00098. The Kashmirian populations seem to have lost cultivated populations).
variation at certain loci (ADH, 6-PGDH-1, PGM-2) prob-  Cultivated buckwheat has much more genetic variabi-
ably during the spread of the cultivation in this area. It lity based on allozyme studies, than the natural popula-
seems reasonable to consider that Kashmirian common tions of the wild ancestor species (F. esculentum ssp.
buckwheat came from the Nepali Himalayan region and lost ancestrale Ohnishi), with both average heterozygosity
variability at certain loci during the spreading process. The and average number of alleles per locus being higher. In
reason for the loss of variability is not clear, but accidental this study, average heterozygosity was found = 0.15,
losses by random drift including the founder principle may and 50% of the loci were polymorphic in common
be more likely than the loss by any selective pressure on the buckwheat, compared to values of 0.1 and 26% for the
alleles involved. No attempt to improve buckwheat has ever wild ancestor, respectively. Since the two species are
been made in this region, and farmers grow buckwheat intercrossable, allozyme variants in wild populations of
from the seeds they harvested the previous season. Thus, the ancestral species may have contributed to the high
according to Ohnishi (1985), the low level of allozyme vari- level of variability in cultivated populations, partially
ability in Kashmirian populations may be interpreted by the explaining the above observation. Further, the large
loss of genetic variability during the spread of cultivation. population size together with the outcrossing breeding
The area of Karakoram and Hindukush (northern system may also have played a role. The case is the
Pakistan) is the western terminus of buckwheat cultivation opposite for tartary buckwheat, a self-fertilizing species,
along the diffusion route south of the Himalayas (Ohnishi with wild populations being genetically more variable
1994). Both common and tartary buckwheats are cultivated than the cultivated populations. Apparently, population
here. Agricultural activity is limited to the valleys of the size is of less importance in case of an inbreeding spe-
river Indus, river Kunar and their tributaries. In most of cies.
these valleys the climate allows two crops a year while at  Most of the evolutionary events which might have taken
higher elevations only one crop is possible. Buckwheats are place during the spread of buckwheat cultivation are the
cultivated as summer crops, after either barley or wheat as losses of variant alleles probably by random genetic
winter crop, in the belt just below the one crop zone. Allo- drift, including founder effects. These events are more
zyme variability showed long genetic distance between the likely to occur in marginal populations with relatively
Pakistan and Tibetan populations of common buckwheat. At small population size, as it is frequently the case when
the same time, no drastic changes in gene frequency were colonizing to new areas. Drastic changes in allele fre-
observed in Karakoram, which is in contrast with the expec- quency, including losses, have only been observed in
tations of marginal populations. The lack of differentiation marginal populations that is Kumaun, Garwhal hills and
at izozyme loci can be explained by the large population Kashmir in India and in southern Europe.
size hence the stable genetic constitution in populations of The final conclusion drawn by Ohnishi (1993b) is that
Karakoram (Ohnishi 1994). As for tartary buckwheat, there the high genetic variability over wide geographical areas
are three distinct groups found in northern Pakistan. These will not make Vavilov’s theory applicable to buckwheat.
are, as listed by Ohnishi (1994), the cultivated, the wild and Vavilov suggested a close relationship between the original
the weedy forms of tartary buckwheat. Cultivated tartary place of domestication and geographical genetic variability.
mainly diffused along the southern hills of the Himalayas, This principle does not hold on buckwheat, mainly because
while the natural populations of the wild tartary (F. of its botanical nature, and the outcrossing breeding system.
tataricum ssp. potanini Batalin) diffused from its original As pointed out earlier by Hutchinson (1965 in Ohnishi
birthplace, Sichuan province of China, to eastern Tibet then 1993b) “It now appears that the classical Vavilov type of
to the Yalutsangpu river valley in Tibet (Ohnishi 1993a). If distribution of variability in a crop plant, with a progressive
this is true, the wild tartary buckwheat in Karakoram and decline in diversity from centre of origin to periphery, is
Hindukush must have come from Tibet, probably via associated with the development of self-pollination.” Buck-
Ladakh, through the old trading routes. As regards the weedy wheat, a complete outcrossing species, became widely dis-
tartary, it has never been reported anywhere else. This form persed without any local differentiation due to strong migra-
has wild characters such as shattering habit and strong tion pressure between populations and between distinct
dormancy, yet morphologically similar to cultivated tartary regions. Buckwheat is a monocentric crop in the sense that
buckwheat. It is hypothesized by Ohnishi (1994) that the it has a definable centre of origin and wide dispersal, with-
weedy form originated from the hybridization of the wild out a secondary centre. In another sense, however, it is a
form and the cultivated form in northern Pakistan after the non-centric crop because it has a pattern of variation that
two forms had come here from the common place of birth suggests domestication over a wide geographical are. This
in different routes of diffusion. theory is supported by the fact that there is no archaeolo-
The same author reported he was unable to find the wild gical evidence of buckwheat cultivation at the original
species perennial buckwheat (F. cymosum) in Karakoram birthplace in Yunnan.
and Hindukush, probably because the climate, and particu- The case of buckwheat contradicts to Vavilov’s theory:

23
 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

centre of origin ≠ centre of diversity ≠ centre of domestica- esculentum ssp. ancestrale Ohnishi) is the most closely
tion. related to cultivated common buckwheat among the pre-
sently discovered wild Fagopyrum species, as regards mor-
Diffusion routes on the studies of DNA-based phology, allozyme variability and RFLP of cpDNA (Ohni-
markers shi and Matsuoka 1996), and the nucleotide sequence of the
rbcL-accD region of cpDNA and the ITS region of nuclear
DNA-based molecular markers have been used to reveal rRNA gene (Yasui and Ohnishi 1998a, 1998b). Also this
diffusion routes of buckwheat cultivation in Asia, and the wild subspecies is able to cross with the cultivated subspe-
results are in accordance with those of earlier studies on cies and produces fertile hybrids (Ohnishi 1999; Konishi et
allozymes. RAPD markers among 29 landraces from Asia al. 2005). Perennial buckwheat (F. cymosum Meisn.) has
were compared in order to clarify major routes of diffusion now been shown to be only distantly related to common
of buckwheat cultivation (Murai and Ohnishi 1995). The buckwheat (Kishima et al. 1995; Ohnishi and Matsuoka
results, a dendogram written by the unweighted pair group 1996; Yasui and Ohnishi 1998a, 1998b). The cross between
(UPG) method and the neighbour joining (NJ) method, F. cymosum and F. esculentum was quite difficult to accom-
clearly indicated that cultivated common buckwheat dif- plish (Woo et al. 1999).
fused to two major directions. One major route is southern The wild ancestor having been identified, the question
China → northern China → Korean peninsula → Japan. to be answered is which part of the distribution area is the
The other major direction is the Himalaya region, mainly original birthplace of cultivated common buckwheat. Re-
through the southern slopes of the Great Himalayas, with current expeditions revealed that natural populations of the
the exact route of southern China → Bhutan → Nepal → wild ancestor of common buckwheat can also be found in
Kashmir → Karakuram, Hindukush. As expected, the the Three Rivers Area (Ohnishi 1998a, 1998b; Tsui et al.
amount of RAPD marker variability sharply decreased as 1999; Konishi and Ohnishi 2001; Ohnishi 2001). The Three
the cultivation of buckwheat diffused from the centre of Rivers Area (San Jiang Area) of southern China is bordering
origin to peripheral parts of the distribution. This shows that the provinces of Yunnan and Sichuan and also eastern Tibet
the total amount of variability maintained in each popula- (Ohnishi 2004). Populations of the wild ancestor were
tion decreased as the diffusion of cultivated buckwheat found here on mountain slopes, along big rivers, and deep
progressed. This finding is not in contradiction with the in mountain areas, however the climate here is rather hot
high genetic variability over wide geographical areas ob- and less humid. The “San Jiang (Three Rivers) area” is a
served in Asian populations. key area for the study on the origin of cultivated common
buckwheat (Ohnishi 2004).
ORIGINAL BIRTHPLACE OF CULTIVATED AFLP analysis was performed to reveal genetic rela-
COMMON BUCKWHEAT tionships among cultivated populations of the crop species F.
esculentum ssp. esculentum and natural populations of the
The theory that F. cymosum is the putative ancestor of com- wild ancestor subspecies F. esculentum ssp. ancestrale in
mon buckwheat was holding until quite recently (Campbell order to locate the original birthplace within the distribution
1976). In 1990 a new, unfamiliar wild buckwheat species area (Konishi et al. 2005). A phylogenic tree was construc-
was found in Yongsheng-xiang of Yunnan province (Ohni- ted by the neighbour-joining method based on genetic dis-
shi 1990). It was very closely related to common buckwheat, tance estimated from the gene frequencies. The natural
and it was identified, based on its morphology, as the wild populations of the ancestral subspecies from the San Jiang
ancestor of F. esculentum. The newly discovered species area were more closely related to cultivated populations
was growing in the wild on rocky cliffs and on roadsides. than natural populations from other regions including popu-
The ancestral species differs from common buckwheat lations from Yunnan and Sichuan. As for the AFLP varia-
in having a fragility of premature seeds, strong seed dor- tions within a population, both cultivated and natural popu-
mancy, longer growth period and branching at lower nodes. lations have retained high level of diversity. On average,
In other respects the two species are similar and are inter- 78.8% of the detected loci were polymorphic with average
crossable. This discovery, combined with the observation of heterozygocity (H) of 0.293 for the cultivated populations.
the richest distribution of wild Fagopyrum species in sou- The corresponding values for the natural wild populations
thern China, indicates that the birthplace of cultivated com- were 0.921 and 0.349, respectively. The approximately
mon buckwheat is southern China, probably Yunnan pro- equal amount of genetic variations in cultivated and natural
vince. This finding is in accordance with earlier izozymes populations agrees well with the results on allozyme varia-
analysis by Ohnishi (1983, 1990). It had been pointed out tions (Ohnishi 1998b). It may be inferred again that com-
that F. cymosum is only distantly related to either F. escu- mon buckwheat might not have suffered from strong bottle-
lentum or F. tataricum. Allozyme studies also pointed out, neck effect during the domestication process. It can be con-
that there is a high level of allozyme variability in any cul- cluded from the study, that natural populations of wild
tivated population of common buckwheat (Ohnishi 1988, common buckwheat from the San Jiang river area are the
1990). This finding supports the idea that common buck- most closely related to cultivated common buckwheat,
wheat has never suffered from a bottleneck effect during its hence they are the strong candidate of the direct wild ances-
domestication. The improvement of common buckwheat tral population. This leads to an assertion that the orginal
from the wild ancestor was probably an evolutionary pro- birthplace of cultivated common buckwheat is the San Jiang
cess, since most of the allozymes present in F. esculentum river area.
are also present in the ancestor species. The wild ancestor This finding of Konishi et al. (2005) was confirmed by
of cultivated buckwheat (F. esculentum ssp. ancestrale Oh- Ohnishi (2007), who surveyed 11 natural populations of the
nishi) was classified as subspecies of the cultivated species wild ancestor (F. esculentum ssp. ancestrale Ohnishi) from
(F. esculentum ssp. esculentum Moench) because they differ various parts of Yunnan, Sichuan and Tibet for their allo-
only in dormancy and shattering habit as key distinguishing zyme variations at 19 loci, together with 12 cultivated popu-
characters (Ohnishi and Matsuoka 1996). lations of common buckwheat from the “San Jiang (Three
The discovery of the wild ancestor (F. esculentum ssp. Rivers) area”. In this study again, the natural populations
ancestrale Ohnishi) of common buckwheat provided the from the “San Jiang” area were most closely related with
first scientific evidence of the probable birthplace of com- the cultivated populations. This study allows us to get closer
mon buckwheat (F. esculentum ssp. esculentum Moench). A to the putative birthplace of the wild ancestor itself within
conclusive evidence for a wild species to be the ancestor of this area. Among the populations surveyed, the Dongyi and
a crop species is based on morphological, cytological and Yiji populations had the highest allozyme variations for this
genetic comparisons and on the study of crossability (Koni- subspecies. “Since diploid F. cymosum, the putative ances-
shi et al. 2005). tor of the wild ancestor of common buckwheat (Yamane et
According to earlier studies, the wild subspecies (F. al. 2003), grows in the Dongyi river valley, we may con-

24
 Origin and distribution of buckwheat. Gondola and Papp

sider that the Dongyi river valley is the center of genetic it, hence they are the most probable candidate of the wild
diversity of the wild ancestor, and the valley is probably the ancestor. Since the direction from a self-incompatible out-
original birthplace of the wild ancestor itself” (Ohnishi breeder to a self-compatible self-fertilizing species is a gene-
2007). ral trend of evolution in the plant kingdom, F. homotro-
picum has been eliminated as a candidate. This has led to
WILD FAGOPYRUM SPECIES the conclusion, that F. esculentum ssp. ancestrale is the wild
ancestor of cultivated common buckwheat. This also asserts
Classification of Fagopyrum species has been modified the place of origin of buckwheat cultivation. It is probably
several times by the discovery of new species. In the 1980s the northwest corner of Yunnan province, judging from the
there were only seven wild species known, beside the two distribution of the wild ancestor species in nature (Ohnishi
cultivated species, in the genus Fagopyrum. With the dis- 1995).
covery of several new species in southern China, the num- Wild tartary buckwheat (F. tataricum ssp. potanini
ber of known wild species increased to about fifteen in the Batalin) is distributed in the northwest part of Yunnan,
1990s, as summarized by Ohnishi (1995, 2001). The newly south-western part of Sichuan and eastern Tibet. Wild tar-
discovered species were F. capillatum Ohnishi, F. callian- tary buckwheat grows on disturbed barren lands, roadsides,
thum Ohnishi, F. pleioramosum Ohnishi and F. homotro- occasionally within barley or rape fields. The populations of
picum Ohnishi, as well as the subspecies F. esculentum ssp. wild tartary buckwheat are not so large, usually consisting
ancestrale Ohnishi. The majority of the species was found of 10 to 500 individuals (Ohnishi 2001). A putative proge-
in two hotspots of differentiation of Fagopyrum. One of nitor for tartary buckwheat, with heterostylic self-incom-
them is the northwest corner of Yunnan province and the patible pollination mechanism has not yet been found
other is the upper Min river valley in Sichuan province of (Ohnishi 1995).
China. The two hotspots have no common wild species. Since the Three Rivers Area is considered to be the ori-
This implies that speciation in Fagopyrum might have taken ginal birthplace of common and tartary buckwheat, inten-
place in those places independently (Ohnishi 1995). All the sive research was focused on it in the 1990s to search for
newly discovered species have a narrow endemic distribu- natural populations of wild Fagopyrum species (Ohnishi
tion, probably because the environmental factors restrict 2004). As described by Ohnishi (2004), rice is the major
their distribution to a narrow territory. Exceptions are the crop produced here by farmers in the lower, warmer areas,
widely distributed F. cymosum (perennial buckwheat, 4x), F. whereas maize production takes the place of rice in the
tataricum ssp. potanini and F. gracilipes. These species higher and cooler areas. Buckwheat and millets are mainly
extend their distribution to the Himalayan hills and the found on the mountain slopes. Of the two buckwheat spe-
Tibetan plateau. Also, some new species were occasionally cies, common buckwheat is produced at a greater extent
found in between the two hotspots (e.g. F. leptopodum). than tartary buckwheat. At elevations higher than 3000 m
Morphological classification of the known species is given cultivation of barley is dominant. Two additional wild spe-
by Ohnishi (1995). cies were found to be growing wild in the Three Rivers
According to Wang et al. (2007), “the distribution of Area: these are F. gracilipes and F. cymosum. The high
wild buckwheat resources in Sichuan is relatively centra- mountains in the Three Rivers Area appear to have been a
lized”, with two main distribution centres. One of them is critical barrier for the distribution of Fagopyrum species.
the Southwest and the other is the North of Sichuan. The Only two species, F. gracilipes and F. cymosum appear to
south-west Sichuan centre is the distribution area of all have overcome this barrier and distributed further westward,
known buckwheat species in this area, with 7 species, 2 as it was discussed above.
varieties and 2 subspecies: F. cymosum, F. urophyllum, F. A new species (F. jinshaense Ohsako et Ohnishi) was
lineare, F. gracilipes, F. statice, F. leptopodum, F. gilesii, F. discovered and registered. This species was found to be
gracilipes var. odontopterum, F. leptopodum var. grossi, F. morphologically similar to F. gilesii and F. leptopodum.
tataricum ssp. potanini and F. esculentum ssp. ancestrale. However, it was shown by molecular phylogenic analysis
In the centre of North there are 4 species, 2 varieties and 2 that F. jinshaense was related to F. gilesii and F. leptopodum
subspecies: F. cymosum, F. urophyllum, F. gracilipes, F. in nuclear DNA, but was related to F. urophyllum in their
leptopodum, F. gracilipes var. odontopterum, F. leptopodum chloroplast DNA (Nishimoto et al. 2003; Ohnishi 2004).
var. grossi, F. tataricum ssp. potanini and F. esculentum ssp. Plant mating systems play a crucial role in shaping the
ancestrale. The 3 most widely spread species are F. graci- genetic composition of populations and determine the distri-
lipes, F. gracilipes var. odontopterum and F. cymosum. They bution of allozyme variation within and among populations.
are growing under varying environmental conditions across Most of the wild species in the genus Fagopyrum have a
the two centres. F. gracilipes and F. gracilipes var. odonto- distylous self-incompatibility system with some species
pterum are major weeds in corn, vegetable and potato fields. being distylous but self-fertilizing and some others homo-
“The reasons are self-pollination, high rate of seed setting, stylous, self-compatible. The question arises whether predo-
easy to drop, small seed size, convenient to spread and fast minantly outcrossing species maintain higher levels of
in breeding.” “F. cymosum is mainly growing on shady and intrapopulation genetic diversity than do predominantly
wet hillside, field side, stone heap, shore of crub, often inbreeding species? The genetic diversity parameters (the
accompanied with perennial herbs or scrubs.” percentage of polymorphic loci, mean number of alleles per
The wild ancestor of both cultivated species had been locus, mean number of alleles per polymorphic locus, total
discovered by the mid-1990s, with the ancestor of common genetic diversity, genetic diversity within populations and
buckwheat (F. esculentum ssp. ancestrale) coming from among populations) were evaluated using enzyme electro-
Yunnan, and that of tartary buckwheat (F. tataricum ssp. phoretic markers, in four Fagopyrum species (Huh et al.
potanini) coming from Sichuan. This may indicate the inde- 2001). Genetic diversity was higher for F. leptopodum
pendent origin of the two species. (heterostylous, outcrossing species) than for F. gracilipes
F. homotropicum, a homostylous, self-fertilizing wild (homostylous, self-fertilizing species), and again higher for
species, has natural populations both in northern Yunnan F. esculentum than for F. tataricum. This observation in
and southern Sichuan, with plants from different locations Fagopyrum is consistent with the general knowledge that
showing different morphology. Both diploid and tetraploid predominantly out-crossing species maintain higher levels
cytotypes of F. homotropicum are distributed in Yunnan and of genetic variation than predominantly inbreeding species.
Sichuan provinces, whereas all the samples from eastern Tetraploid forms of shrubby perennial buckwheat (F.
Tibet were tetraploid (Konishi and Ohnishi 2001). After the cymosum) have a wider distribution than diploid forms. An
discovery of F. esculentum ssp. ancestrale and F. homotro- interesting observation is that certain tetraploid populations
picum, it became clear from subsequent analysis on phylo- in Indochina and India completely lack thrum plants, and
genic relationship that both species are closely related to only consist of pin plants. These populations are sterile, and
cultivated common buckwheat, both are intercrossable with can only propagate and diffuse by vegetative organs (Ohni-

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 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

shi 1989; Tahir and Farooq 1992). The possibility was sug- detectable at the protein level, the power of the technique to
gested that the thrum-lacking population of F. cymosum is supply detailed genetic information lags behind the power
an intermediate evolutionary step from the diploid species of modern PCR based methods or proper sequence infor-
to the fertile tetraploid species (Ohnishi 1989). mation. The obtained molecular information is suitable for
phylogenic studies at interspecific taxonomic levels. Des-
PHYLOGENIC RELATIONSHIPS OF FAGOPYRUM pite the limitation of this method, several studies on popu-
SPECIES lation genetics of buckwheat were published before the
PCR era (Ohnishi 1985, 1988, 1993b; Ohnishi and Nishi-
There have been numerous efforts to determine the phylo- moto 1988), and this method was also used to determine
genic relations and possible speciation in Fagopyrum. The phylogenic relationship between eleven Fagopyrum species
studies not only differ in the particular approach to obtain (Ohnishi and Matsuoka 1996).
and analyze data, but also in the sampling strategy. The
number of samples varied by accessions/species and also by 2. Use of nuclear DNA sequences
locations for both wild and cultivated populations. The
method used may have a significant influence on the bran- One of the most popular sequences for phylogenic inference
ching of the phylogenic tree obtained. As for the present at the generic and infrageneric levels in plants is the internal
work, there would be no sense in trying to synthesize the transcribed spacer (ITS) region of the 18S-5.8S-26S nuclear
phylogenic trees from different studies in one single tree. ribosomal cistron. The ITS region is a suitable target to
However, phylogenic relationships in Fagopyrum can be investigate plant phylogenic relationship among closely
presented by naming those clades identified in the majority related genera or species because of its rapid evolution
of the studies and by citing the appropriate papers for (Baldwin 1992; Baldwin et al. 1995) and homogenization
support. among repeat units through concerted evolution (Arnheim
The first attempts to uncover phylogenic relations in 1983). It was observed that the sequences of the 5.8S sub-
Fagopyrum were based on different morphological clas- unit are conserved at the same level as other coding regions,
sifications by Steward (1930) and Hedberg (1946), and later while the sequences of ITS are much more variable.
some other studies were published (Ye and Guo 1992; Hirose However, there are some complications for phylogenic
et al. 1994, 1995; Ohnishi and Matsuoka 1996; Ohsako and inference of sequence data of the ITS region in many plant
Ohnishi 1998; Ohsako et al. 2002). The key characters for a genomes because extensive sequence variations may derive
new morphological classification in Fagopyrum were des- from ancient or recent array duplication events, genomic
cribed in Ohnishi and Matsuoka (1996). Meanwhile, several harboring of pseudogenes in various states of decay, and/or
new molecular genetic methods have been developed giving incomplete intra- or inter-array homogenization. These
the opportunity of combining their power to construct the phenomena separately and collectively create a network of
phylogenic tree which is able to represent the true relation- paralogous sequence relationships potentially confounding
ships among Fagopyrum species. accurate phylogenic reconstruction (Alvarez and Wendel
A strange characteristic of the work was the recurrent 2003).
need to repeatedly redraw the intra- and interspecific phylo- DNA sequence data of internal transcribed spacer (ITS)
genic relationships enforced by frequent discovery and des- region of the rRNA gene were obtained from different
cription of new Fagopyrum species in the late 1990’s (Oh- buckwheat species and used for phylogenic analyses. The
nishi 1998a, 1998b; Ohsako and Ohnishi 1998) and even in ITS region contains the complete ITS1, ITS2 sequences and
the following decade (Ohsako et al. 2002). the 5.8S subunit of the rRNA gene. The region could be
Before discussing the phylogenic relationships, a short obtained by PCR amplification of a short (700 bp) fragment,
survey is given on the methods used to obtain the primary and its sequence can be determined directly from PCR pro-
data. duct or after its cloning. The sequences of ITS1 and ITS2
were about 3-7 times more variable than the sequence of the
Methods of phylogenic studies 5.8S subunit of the rRNA gene (Yasui and Ohnishi 1998b).
ITS sequence information were used for phylogenic analy-
1. Isozyme variability ses in the identification of several new Fagopyrum species
(Ohsako and Ohnishi 1998).
Studies of isozyme variability in buckwheat were based on Despite the near-universal usage of ITS sequence data
electrophoretic analyses of 12 enzymes, representing 19 in plant phylogenic studies, its complex and unpredictable
loci, described in Ohnishi and Nishimoto (1988). The en- evolutionary behavior reduces its utility for phylogenic ana-
zymes such as alcohol dehydrogenase (Adh, EC 1.1.1.1), lysis. It is suggested that more robust insights are likely to
glutamate dehydrogenase (Gdh, EC 1.4.1.2), fumarase emerge from the use of single-copy or low-copy nuclear
(Fum, EC 4.2.1.2), isocytrate dehydrogenase (Idh, EC genes.
1.1.1.42) and leucine aminopeptidas (Lap, EC 2.6.1.1) are Low-copy nuclear genes in plants are a rich source of
determined by one locus. Phosphoglucomutase (Pgm, EC phylogenic information. They hold a great potential to im-
2.7.5.1), 6-phosphogluconate dehydrogenase (6-Pgdh, EC prove the robustness of phylogenic reconstruction at all
1.1.1.44) and shikimate dehydrogenase (Sdh, EC 1.1.1.25) taxonomic levels. Low-copy nuclear genes, however, remain
are determined by two loci. At least two loci are involved in underused in plant phylogenic studies due to practical and
diaphorase (Dia, EC 1.6.4.3), three in tetrazolium oxidase theoretical complications in unraveling the evolutionary
(Tox, superoxide dismutase EC 1.15.1.1) and glutamate- dynamics of nuclear gene families. The lack of the universal
oxaloacetate transaminase (Got, EC 2.6.1.1), probably five markers or universal PCR primers of low-copy nuclear
(or more) in NAD-dependent malate dehydrogenase (Mdh, genes has also hampered their phylogenic utility. It has
EC 1.1.1.37), respectively. Seed samples were used to assay become clear that low-copy nuclear genes are particularly
the Adh, Fum, Gdh, Got-1, Idh, Lap, Mdh-1, Mdh-5, Pgm-1, helpful in resolving close interspecific relationships and in
Pgm-2, 6-Pgdh-1, 6-Pgdh-2, Tox-1 and Tox-2 loci, while the reconstructing allopolyploidization in plants (Sang 2002).
first or second foliage leaves were used to assay the re- Two floral homeotic genes, FLORICAULA/LEAFY
maining loci, such as Dia-1, Dia-2, Got-2, Lap, Mdh-3 and (FLO/LFY) and AGAMOUS (AG), thought to be single/low-
Sdh-1 (Ohnishi and Nishimoto 1988). Assignment of geno- copy genes in Fagopyrum, were used to analyze phylogenic
types was based on the observed bandmorphs at the poly- relationships in the Urophyllum group (Nishimoto et al.
morphic loci as well as on the known linkage relationships 2003). Conserved regions of FLO/LFY have been used pre-
between isozyme loci. viously for phylogenic analyses at higher taxonomic levels
When isozyme variability is used for analysis, geno- (Himi et al. 2001), while the long intronic sequence of AG
types are deduced from protein data. Due to the lower varia- contributed to its phylogenetic utility at lower taxonomic
bility of coding regions, particularly allele differences levels.

26
 Origin and distribution of buckwheat. Gondola and Papp

3. DNA fingerprinting mation from different regions of the chloroplast genome

were used to reveal phylogenic relationships among Fago-
Random amplified polymorphic DNA (RAPD) is a PCR pyrum species. Some advantages come from the combina-
based fingerprinting method which provides molecular data tion of using single-copy genes and the features of non-mei-
in an efficient, simple an inexpensive way. Although this otic and uniparental inheritance of the chloroplast genome.
method has been employed in many plants for both taxo- All three regions, used in the different studies, are located in
nomic and phylogenic studies, there are only a few studies the large single-copy region (LSC) of the chloroplast
concerning buckwheat. RAPD was used for phylogenic genome. The nucleotide substitution rate of plant chloro-
studies of cultivated landraces and natural populations of plast DNA (cp-DNA) is lower that of nuclear DNA (Wolfe
tartary buckwheat (Tsuji and Ohnishi 2000, 2001a) and for et al. 1987) but sequences of coding and intergenic spacer
determination of relationship among 14 species and two regions can be used together for phylogenic analyses.
sub-species of Fagopyrum (Sharma and Jana 2002). The sequences of the rbcL gene, which encodes the
Amplified fragment length polymorphism (AFLP) is a large subunit of ribulose-1,5,-biphosphate carboxylase/oxi-
powerful method to detect polymorphisms, however, for dase, have been used widely to construct plant phylogenies.
researchers wanting to use AFLP, this molecular technique However, these phylogenic studies have been limited at
is difficult and time-consuming to adapt to the species of taxonomic levels above subfamilies, because the rbcL gene
interest. This might be a reason why AFLP has been em- has a slow base substitution rate (Doebley at al. 1990). In
ployed so rarely for phylogenic studies of buckwheat spe- Fagopyrum and related genera of Polygonaceae, analyses
cies. The AFLP technique was used to investigate phylo- of the DNA sequences of rbcL were successful to separate
genic relationships among cultivated landraces and natural Fagopyrum from other related genera of Polygonaceae and
populations of wild subspecies of tartary buckwheat (Tsuji to classify major groups of Fagopyrum (Yasui and Ohnishi
and Ohnishi 2001b; Park et al. 2006) as well as among 1996). To obtain sequence information suitable for studying
cultivated and natural populations of common buckwheat at phylogenic relationship at lower taxonomic levels, the
the individual level (Konishi et al. 2005). sequenced region was extended downstream from rbcL into
Restriction fragment length polymorphism (RFLP), a the 5' region of the next gene, accD, in the chloroplast
rather old DNA fingerprinting technique was used to ana- genome. The 5' coding region of the accD gene, which en-
lyze chloroplast genome DNA (cpDNA) in Fagopyrum. The codes one of the subunits of acetyl-CoA carboxilase, and
molecular size of the total chloroplast genome was found to the intergenic region between the two genes differ greatly
be approximately 155 kbp in all the buckwheat species from species to species (Nagano et al. 1991). Phylogenic
examined (Kishima et al. 1995) which is small enough to analyses of the genus Fagopyrum, based on nucleotide se-
visualize band patterns obtained by electrophoretic sepa- quence of the rbcL-accD coding and their intergenic region
ration of fragments following restriction digestions with in cp-DNA, has been reported (Yasui and Ohnishi 1998a;
different enzymes (Ohnishi and Matsuoka 1996). Although Oshako et al. 2001).
this technique is very simple and combines the advantage of Another region in the chloroplast genome, used in phylo-
using chloroplast in determining phylogenic relationship genic studies, is the intron of the trnK (UUU) gene, inclu-
(non-meiotic and uniparental inheritance), it became ana- ding the matK gene. The trnK intron comprises three
chronistic by the technical simplicity of obtaining detailed regions: the matK gene, which is an intron-internal open
sequence information. reading frame that is thought to encode a maturase-like pro-
tein (Neuhause and Link 1987), and two non-coding regions
4. Use of chloroplast DNA sequences flanking both sides of the matK gene. Phylogenic relation-
ships of new Fagopyrum species based on trnK intron se-
Chloroplast genome sequences are extremely informative quences (Ohsako et al. 2002), as well as studies on intra-
about species-interrelationships owing to its non-meiotic specific polymorphisms and interspecific divergence of the
and often uniparental inheritance over generations. The com- trnK/matK region within and between two wild Fagopyrum
plete chloroplast genome sequence of the wild ancestor of species (Ohsako and Ohnishi 2001) have been reported.
cultivated buckwheat, Fagopyrum esculentum ssp. ances- Nucleotide sequences in the intragenic spacer between
trale has been reported recently (Logacheva et al. 2008). trnC(GCA) and rpoB genes of cp-DNA have also been used
The gene content and order in buckwheat chloroplast in several phylogenic studies. Due to the higher nucleotide
genome was found to be similar to Spinacia oleracea with variation in this region, intra- and interspecific phylogenic
some unique structural differences in buckwheat, such as relationships can be determined. Molecular phylogeny based
the presence of an intron in the rpl2 gene, a frameshift on trnC-rpoB spacer region sequences was applied to verify
mutation in the rpl23 gene and extension of the inverted the existence of two distinct groups in natural populations
repeat region to include the ycf1 gene. Phylogenic analysis of F. urophyllum (Kawasaki and Ohnishi 2006).
of 61 protein-coding gene sequences from 44 complete The certainty to reveal true phylogenic relationships
plastid genomes (representing all major lineages of angio- among species could be increased by using molecular data
sperms) provided strong support for the sister relationships from two or three regions of the cp-DNA simultaneously. In
of Caryophyllales (including Polygonaceae) to Asterids Fagopyrum, using sequence information of the trnK intron
(Logacheva et al. 2008). and trnC-rpoB spacer regions (Ohsako and Ohnishi 2000),
The size of the chloroplast genome of F. esculentum ssp. as well as nucleotide sequences of the rbcL-accD, trnK
ancestrale is composed of 159599 nucleotide bases, and it intron and trnC-rpoB spacer regions (Nishimoto et al. 2003;
exceeds the average size of flowering plant’s chloroplast Yamane et al. 2003), have been reported.
genomes ~155 kbp. The observed increase in size is due to Combination of two or more methods mentioned above
the expansion of the inverted repeat (IR) region. The inver- can increase further the certainty of the revealed phylogenic
ted repeats (IRa and IRb) separate the genome into small relationships.
(SSC) and large (LSC) single-copy regions. It was shown
that the expansion was not only a characteristic of Fago- Results of phylogenic studies
pyrum but it was also found in some other related genera
and this may represent a common feature in Polygonaceae. 1. Current view on phylogenic relations based on the
Comparative analysis of the various sequences derived from above studies
buckwheat species revealed minor variations in the fine
structure of the IR/SSC borders (Logacheva et al. 2008). Phylogenic relations of Fagopyrum species have been in-
Further studies of the fine structure of IR/SSC borders can ferred from morphological data as well as molecular infor-
be of utility to illustrate phylogenic relationships within mation obtained by using one or more of the methods
Fagopyrum. reviewed above. There are several well-known, accepted
There are a number of studies in which sequence infor- methods to analyze the data to reveal relationships at both

27
 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

intra- and interspecific taxonomic levels and usually presen- 2002). F. rubifolium was added to this clade later (Ohsako
ted in a form of a phylogenic tree. Phylogenic trees from and Ohnishi 2000; Ohsako et al. 2001). The F. macrocar-
different studies greatly vary as they are influenced by seve- pum – F. pleioramosum – F. callianthum clade, where the
ral factors, such as sampling strategy, the method used to first two species were close relatives, was reported in some
obtain and analyse data. of the studies (Ohsako and Ohnishi 1998, 2000; Ohsako et
None of the studies have questioned the general view al. 2001, 2002; Nishimoto et al. 2003). F. gilessii was not
that species in genus Fagopyrum fall into two major mono- usually clustered together with any of the clades (Ohsako et
phyletic groups, namely the cymosum group and the uro- al. 2001, 2002; Sharma and Jana 2002) except with F. jin-
phyllum group. shaense (Nishimoto et al. 2003). The sister clade composed
by F. jinshaense and the Kunming group of F. urophyllum
2. Phylogeny within the cymosum group could be seen in Nishimoto et al. (2003). Phylogenic ana-
lysis revealed that the debated F. megacarpum should be
Three clades can be recognized within the cymosum group. excluded from genus Fagopyrum (Ohsako et al. 2001).
The F. esculentum-F. homotropicum clade comprises two
subspecies of F. esculentum, notably the cultivated ssp. BOTANICAL DESCRIPTION OF SOME SELECTED
esculentum (Moench) and its wild ancestor ssp. ancestrale FAGOPYRUM SPECIES WITH BOTANICAL NAMES
(Ohnishi) grouped together and separated from the closely AND SYNONYMS
related F. homotropicum (Ohnishi) (Ohnishi and Matsuoka
1996; Yasui and Ohnishi 1998a, 1998b). The majority of the This section and information contained herein is based on
studies revealed a strong relationship between F. cymosum information from eFloras 2008 (www.eFloras.org; Missouri
(Meisn.) and the two F. tataricum subspecies, the cultivated Botanical Garden, St. Louis, MO and Harvard University
ssp. tataricum (Gaertn.) and its wild relative ssp. potanini Herbaria, Cambridge, MA).
(Batalin). These three species were considered as the sec-
ond clade of the cymosum group (Ohnishi and Matsuoka Cymosum group
1996; Yasui and Ohnishi 1998a; Nishimoto et al. 2003). The
inclusion of several accessions of F. cymosum in the studies 1. Fagopyrum esculentum Moench, Methodus. 290. 1794.
resulted in dividing this clade into two clades (Yasui and
Ohnishi 1998b). The phylogenic relationships within F. “Hook.f., l. c. 55; D. A. Webb in Tutin et al., Fl. Europ. 1:
cymosum coincide with geographic locations of the acces- 81. 1964; Kitamura, Pl. Afgh. and W. Pak. 43. 1964; Rech. f.
sions. The Tibet-Himalayan clade included both F. tatari- and Schiman-Czeika, l. c. 83; R.R.Stewart, l. c. 202; Bhopal
cum subspecies, the Yunnan-Sichuan clade only consisted and Chaudhri in Pak. Syst. 1(2): 87. 1977; Grierson and D.
of F. cymosum accessions. It was suggested that F. tatari- G. Long, Fl. Bhutan 1(1): 171. 1983; Munshi and Javeid,
cum speciated from F. cymosum in the Tibet-Himalayan Syst. Stud. Polygon. Kashm. Himal. 83. 1986.
area (Yamane et al. 2003). It was shown that Fagopyrum Polygonum fagopyrum L., Sp. Pl. 364. 1753; Fago-
giganteum (a hybrid species between F. tataricum and F. pyrum sagittatum Gilib, Exerc. Phyt. 2: 435. 1792 - nom.
cymosum), F. pilus and F. cymosum clustered together illegit.; Polygonum emarginatum Roth, Catalect. B. 1: 48.
(Sharma and Jana 2002). 1797; Fagopyrum vulgare T. Nees, Gen. Pl. Fl. Germ.
Monochlam. 53. 1835.”
3. Phylogeny within the urophyllum group English: Common buckwheat
French: Sarrasin commun
The results of the numerous studies addressing phylogenic “Annual, up to 1 m tall herb, glabrous or young parts
relationships within the urophyllum group of genus Fago- rarely minutely papillose. Stem ribbed, reddish. Leaves
pyrum are not congruent. The results of a recent study by petiolate, petiole 0.5-2 cm long, grooved lower leaves with
Kawasaki and Ohnishi (2006) are presented here and com- long petiole, upper ones subsessile; lamina triangular or
pared to findings of other studies. sagittate, cordate, basal lobes rounded to acuminate, 1.5-10
The species F. urophyllum was divided into two distinct × 1-8 cm. Ochrea 2-3 (-5) mm long, hyaline, pubescent near
groups, the Dali group and the Kunming group, based on the base. Inflorescence axillary and terminal, pedunculate,
morphological characteristics, and the classification was many-flowerd corymbose cyme. Flowers pink or red, pedi-
verified by molecular phylogeny. It is suggested that the celled, c. 1 mm across. Perianth segments 5-partite, ovate or
two groups should be handled as subspecies or two distinct oblong-ovate c. 3 × 2 mm broad. Stames 8, unequal, alter-
species on the basis of their reproductive isolation. These nating with glands, c. 1.5 mm long. Ovary 3-angled; styles
two groups were recognized also in previous studies (Ohni- 3, as long as ovary. Nuts deeply 3-angled, angles acute,
shi and Matsuoka 1996; Yasui and Ohnishi 1998a, 1998b; brown, smooth, narrowed at both the ends, 4-8 × 2.5-5 mm
Ohsako and Ohnishi 2000). Clades within the urophyllum broad.” 2n = 16.
group are (Kawasaki and Ohnishi 2006): Flowering: June-August. Fruiting: July – September.
F. leptopodum – F. statice Flowers are chasmogamous, heterostylous. Obligate
F. gracilipes – F. rubifolium – F. gracilipedoides – F. out-crosser.
capillatum Habitat in Asia.
F. macrocarpum – F. pleioramosum – F. callianthum Illustration:
F. gilessii http://efloras.org/object_page.aspx?object_id=44793&flora
Kunming group of F. urophyllum – F. jinshaense _id=5
Dali group of F. urophyllum – F. lineare.
The Kunming group of F. urophyllum and F. jinshaense 2. Fagopyrum tataricum (L.)
formed a sister clade, and a sister clade was also formed by
the Dali group of F. urophyllum and F. lineare (Kawasaki “Gaertn., Fruct. Sem. Pl. 2: 182. t. 119, f. 6. 1791; Hook. f.,
and Ohnishi 2006). The F. leptopodum – F. statice clade l. c. 55; Losinsk. in Kom., Fl. URSS 703. 1936; D. A.Webb
was supported by additional studies (Yasui and Ohnishi in Tutin et al., Fl. Europ.1: 81. 1964; Kitamura, l. c.; Rech. f.
1998a; Ohsako and Ohnishi 1998, 2000, 2001; Ohsako et al. and Schiman-Czeika, l .c. 83; R. R.Stewart. l.c. 202; Bhopal
2001, 2002). The existence of the F. gracilipes – F. rubi- and Chaudhri in Pak. Syst. 1(2): 88. 1977; Munshi and
folium – F. gracilipedoides – F. capillatum clade had also Javeid, l. c. 84; Grierson and D. G. Long, l. c.”
been previously revealed by Ohsako et al. (2002) and Nishi- Polygonum tataricum Linnaeus, Sp. Pl. 1: 364. 1753.
moto et al. (2003), while the close relationships between F. “Annual, glabrous, commonly green herb, up to 1 m tall,
gracilipes and F. capillatum was recognized in the majority stem glabrous or slightly pubescent. Leaves petioled, peti-
of the studies (Ohnishi and Matsuoka 1996; Ohsako and ole 0.5-6 cm long, the upper short and lower long petioled;
Ohnishi 1998; Yasui and Ohnishi 1998a; Sharma and Jana lamina broadly triangular-cordate, triangular-hastate or

28
 Origin and distribution of buckwheat. Gondola and Papp

sagittate-cordate, acuminate, 2-8 × 1.2-5 cm. Ochrea hya- narrowly funnel-shaped, 2-2.5 mm, apex acute, each 3- or
line, slightly truncate, 5-7 mm long, brown. Inflorescence 4-flowered. Pedicels longer than bracts, 3-3.5 mm, slender,
axillary and terminal, pedunculate, corymbose cyme. apex articulate. Perianth white; tepals elliptic, 2-3 mm. Sta-
Flowers white or pink. Perianth segments 5-partite, sub- mens included. Styles free; stigmas capitate. Achenes
equal, oblong-ovate, obtuse, entire, 1.3-1.7 × c. 0.5-1. Sta- exceeding persistent perianth, black-brown, shiny, broadly
mens 8, alternating with rounded glands, filaments unequal ovoid, sharply trigonous, 3-4 mm.” 2n = 16.
with dorsifixed anthers. Ovary 3-angled; styles 3, free, half Flowering: April – September. Fruiting: May – Novem-
the length of the ovary; stigmas capitate. Nuts deeply 3- ber.
angled, angles rounded in the upper part, and wrinkled and Flowers are heterostylous. Cross-fertilization.
somewhat crenate in the lower part, blackish-brown, 4-6 “Grassy or gravelly slopes, thickets in valleys; 900-
mm long, 1.5-2 mm broad, narrowed above.” 2n = 16. 2800 m. Sichuan, Yunnan (China)”.
Flowering: May – September. Fruiting: June – October. Illustration:
Flowers are cleistogamous, homostylous. Self-fertiliza- http://efloras.org/object_page.aspx?object_id=50736&flora
tion. _id=2
Habitat: Central Asia.
Illustration: 2. Fagopyrum gilesii (Hemsl.)
http://efloras.org/object_page.aspx?object_id=50735&flora
_id=2. “Hedb. in Svensk. Botanisk. Tidskrift. 40(4):390. 1946.
Polygonum gilesii Hemsl. in Hook. Icon Pl. t. 1756,
3. Fagopyrum dibotrys (D. Don) 1887-88; Rech., f. and Schiman.-Czeika in Rech. f., Fl. Iran.
56: 55. 1968; R. R. Stewart, l. c. 206.
“Hara, Fl. E. Himal. 69. 1966; 2: 22. 1971; Hara in Hara et Erect, 25-60 cm high, branched, glabrous - pubescent,
al., Enum. Fl. Pl. Nep. 3: 174. 1982; Munshi & Javeid, l. c. perennial herb. Stem circular, glabrous, woody, branched,
82; Grierson and D. G. Long, l. c. leaves very few, internodes quite long. Lower leaves 10-15
Polygonum dibotrys D. Don, Prod. Fl. Nep. 73. 1825; × 8-15 mm, ovate-orbicular, obtuse, entire, long petiolate,
Polygonum cymosum Trev. in Nov. Act. Acad. Caes. Leop.- petiole 1-3 cm long, upper leaves 4.0-8.0 × 2.5-6.0 mm,
Carol. Nat. Cur. 13: 177. 1826; Fagopyrum cymosum ovate, obtuse, entire, petiole 1-2 mm long. Ochrea minute,
(Trev.) Meisn. in Wall., Pl. As. Rar. 3: 63. 1832; Hook. f., l. 1-2 mm long, lanceolate, acuminate, oblique. Inflorescence
c. 55; R. R. Stewart, Ann. Cat. Vasc. Pl. Pak. Kashm. 201. axillary - terminal, 2-5 mm long, few flowered, capitulate
1972; Bhopal & Chaudhri, l. c. 88. or fasciculate raceme. Flowers up to 1.5 mm across, pedicel
F. megaspartanium Q. F. Chen; F. pilus Q. F. Chen; P. c. 0.5 mm. Ochreolae 1-2 mm long, lanceolate, margin
acutatum Lehmann; P. labordei H. Léveillé & Vaniot; P. mambranous. Perianth segments 5, parted to base, 2.0-2.5 ×
tristachyum H. Léveillé; P. volubile Turczaninow. 1.25-1.5 mm, oblanceolate - obovate, obtuse, entire, un-
Herbs perennial. Rhizomes black-brown, stout, ligneous. equal. Stamens 8, filaments short, unequal, anthers basi-
Stems erect, green or brownish, 40-100 cm tall, much bran- fixed. Ovary small, 0.75-1.0 × c. 0.5 mm, lanceolate, trigo-
ched, striate, glabrous. Petiole 2-10 cm; leaf blade triangular, nous, with three styles and capitate stigmas. Nuts trigonous,
4-12 × 3-11 cm, both surfaces papillate, base nearly hastate, glabrous, brown.” 2n = 16.
margin entire, apex acuminate; ocrea brown, 5-10 mm, Flowering: July-August. Fruiting: August-September.
membranous, oblique, apex truncate, not ciliate. Inflores- Flowers are heterostylous. Cross-fertilization.
cence terminal or axillary, corymbose; bracts ovate-lance- Grassy slopes, valleys; 2200-4000 m. Sichuan, Yunnan
olate, ca. 3 mm, margin membranous, apex acute, each 4- (China), Pakistan.
flowered, rarely 6-flowered. Pedicels equaling bracts, arti- Illustration:
culate at middle. Perianth white; tepals narrowly elliptic, ca. http://efloras.org/florataxon.aspx?flora_id=5&taxon_id=24
2.5 mm. Stamens included. Styles free; stigmas much 2100053
exceeding persistent perianth, capitate, opaque. Achenes
blackish brown, dull, broadly ovoid, 6-8 mm, trigonous, 3. Fagopyrum leptopodum (Diels)
sometimes narrowly winged, angles smooth to repandous,
apex acute.” 2n = 16, 32. “Hedberg, Svensk Bot. Tidskr. 40: 390. 1946.
Flowering: April – October. Fruiting: May – November. Herbs annual. Stems 6-30 cm tall, slender, glabrate,
Flowers are heterostylous. Cross-fertilization. branched at base, leafless above. Petiole 1-1.5 cm, slender;
“Moist valleys, grassy slopes, 300-3200 m. It is con- leaf blade triangular or triangular-ovate, abaxially papillate
sidered to be a good fodder plant. The leaves are used as along veins, adaxially scabrous, midvein slightly prominent
vegetable. The grains are used in stomach disorders; Distri- abaxially, base sagittate or nearly truncate, margin entire,
bution: India, China and Pakistan.” apex acute; ocrea white or brownish, membranous, oblique,
Illustration: apex acute. Inflorescence racemose, dense or very lax, seve-
http://efloras.org/object_page.aspx?object_id=7504&flora_i ral racemes together large and panicle-like; bracts membra-
d=5. nous, oblique, apex acute, each 2- or 3-flowered. Pedicels
longer than bracts, ca. 3 mm, slender, apex articulate. Peri-
Urophyllum group anth white or pinkish; tepals elliptic, 1.5-2.5 mm. Stamens
included. Styles filiform, free; stigmas capitate. Achenes
1. Fagopyrum urophyllum (Bureau & Franchet) exceeding persistent perianth, yellow-brown, ovoid, trigo-
nous, 2-2.5 mm.” 2n = 16.
"H. Gross, Bull. Acad. Int. Géogr. Bot. 23: 21. 1913. Flowering: May-October. Fruiting: June-November.
Polygonum urophyllum Bureau & Franchet, J. Bot. Flowers are heterostylous. Cross-fertilization.
(France) 5: 150. 1891; Fagopyrum mairei (H. Léveillé) H. Mountain slopes, valleys; 1000-3000 m. Sichuan, Yun-
Gross; P. mairei H. Léveillé. nan.
Subshrubs. Stems suberect, 60-90 cm tall, much bran- Illustration:
ched; branches ligneous, bark red-brown, exfoliating, sim- http://efloras.org/object_page.aspx?object_id=50734&flora
ple, herbaceous, green striate. Petioles 2-5 cm, shortly _id=2
pubescent; leaf blade greenish abaxially, green adaxially,
sagittate or ovate-triangular, 2-8 × 1.5-4 cm, both surfaces 4. Fagopyrum gracilipes (Hemsley)
shortly pubescent along veins, base broadly sagittate, mar-
gin entire, apex long acuminate or caudate; ocrea brown, 4- “Dammer ex Diels, Bot. Jahrb. Syst. 29: 315. 1900.
6 mm, membranous, oblique. Inflorescence terminal, pani- Polygonum gracilipes Hemsley, J. Linn. Soc., Bot. 26:
culate, 15-20 cm; branches spreading, lax; bracts greenish, 340. 1891; Fagopyrum bonatii (H. Léveillé) H. Gross; F.

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 The European Journal of Plant Science and Biotechnology 4 (Special Issue 1), 17-32 ©2010 Global Science Books

odontopterum H. Gross; P. bonatii H. Léveillé; P. graci- species within the genus, were sufficient to clarify major
lipes var. odontopterum (H. Gross) Samuelsson; P. odon- issues and complement morphological observations. How-
topterum (H. Gross) H. W. Kung. ever, more sequence based information is needed to further
Herbs annual. Stems erect, 20-70 (-80) cm tall, branched refine the picture. It is hard to predict when, but it is un-
at base, striate, sparsely shortly strigose. Petiole 1-3 cm, doubted that decreasing cost of the highly efficient new
shortly strigose; leaf blade ovate-triangular, 2-4 × 1.5-3 cm, generation sequencing methods and the increasing interests
both surfaces sparsely shortly strigose, base cordate or has- in buckwheat breeding will result in determination of the
tate, apex acuminate; ocrea 4-5 mm, membranous, shortly sequence of the entire buckwheat genome. Using routinely
strigose, oblique, apex acute. Inflorescence axillary or ter- sequences of the complete chloroplast and/or large regions
minal, racemose, interrupted, pendulous, very lax, 2-4 cm, of the genomes from different Fagopyrum species will en-
slender; bracts green, funnel-shaped, margin membranous, hance our capabilities to finalize answers for evolutionary
each 2- or 3-flowered. Pedicels longer than bracts, slender, and phylogenic questions as well as promote efficient buck-
apex articulate. Perianth pinkish; tepals elliptic, unequal, 2- wheat breeding.
2.5 mm, with conspicuous green veins. Stamens included.
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