PUCCINIA PATH

Systematic Position of Puccinia Pathogen

Kingdom: Fungi

Division: Basidiomycota

Class: Pucciniomycetes

Order: Pucciniales

Family: Pucciniaceae

Genus: Puccinia

Introduction:

Rust pathogens are a group of fungal organisms that cause rust diseases in plants. They are
part of the Pucciniales order, and these pathogens typically produce reddish or orange pustules on
the leaves, stems, or other plant parts, hence the name "rust." Rust diseases can significantly
impact crop production, reducing yield and quality. There are 5 stages of rust lifecycle they are

 Spermatia (0)
 Aeciospores (I)
 Urediniospores (II)
 Teliospores (III) and
 Basidiospores (IV)

Life cycle of Puccinia:

Rust Pathogen in the United States and India

Rust diseases in wheat were first reported in the United States by Stakman. In India, it was
identified by K.C. Mehta, who emphasized that the barberry plant does not play a role in rust
propagation in India, differing significantly from other regions where the barberry is part of the
pathogen’s life cycle.

Puccinia Path in India

In India, the Puccinia pathogen originates from Nepal. Wheat crops are typically sown in
August and harvested by January. The rust infection begins in October, spreading northward and
infecting wheat crops in northern states by February. From these northern areas, the pathogen
migrates southward during the summer, with spores persisting in self-sown or volunteer wheat plants
in regions such as the Nilgiris and Palani hills. In these areas, the pathogen remains viable
throughout the year, with wheat serving as a continuous host.

Terms Related to Rust

 Source Area: Locations where spores are consistently produced.

 Target Area: Regions where the wheat crop is susceptible to infection.

Rust spores are capable of traveling up to 1,000 km through long-distance dispersal (LDD),
primarily by wind. Rust pathogens spread through various mechanisms, including:

1. Wind: The primary mode of long-distance dispersal.

2. Waterborne Movement: Spores are carried by rain or irrigation systems.

 3. Seed Contamination: Infected seeds can introduce spores to new locations.

4. Soil and Human Activity: Farming tools, clothing, and animals contribute to localized
spread.

5. Birds: Act as incidental carriers, aiding rust's mobility.

Source Strength of Rust Pathogens

Source strength refers to the ability of a location to produce a large number of urediniospores that
are capable of being dispersed over long distances. This is determined by factors such as:

1. Number of Urediniospores Produced

2. Irreducible Longevity: The ability of the spores to remain viable for long periods.

3. Duration of Correlation: The length of time the spores remain active and capable of
infecting new plants.

Characteristics of Spores for Long-Distance Dispersal

For urediniospores to successfully disperse over long distances, they must possess the following
attributes:

1. Resistance to Environmental Stress:

o Ability to withstand dry weather and low temperatures.

2. Thick Spore Walls:

o Pigmentation in spore walls (such as melanin) protects the spores from UV radiation,
allowing them to survive atmospheric transport.

Role of Wind in Rust Pathogen Dispersal

Wind plays a pivotal role in the long-distance dispersal of rust pathogens. The process of
spore movement involves three main stages: take-off, transport, and deposition. Atmospheric
dynamics influence the direction and distance that spores can travel. The process can involve a
turbulent boundary layer at 2 km above ground level, where wind currents carry spores up to 10 km
high, allowing for the deposition of spores over vast distances.
Global Spread of Rust Pathogens

Turkey to India

 Rust pathogens spread from Turkey to India through western disturbances in the
Mediterranean Sea, primarily between January and February. These disturbances facilitate
the movement of spores into the Indian subcontinent.

South Mexico to Northern USA

 Birds have been observed to assist in the dispersal of rust pathogens, spreading spores from
South Mexico to the Northern United States.

Blackberry Rust in Australia

 The Blackberry Rust Pathogen (Phragmidium violaceum) was introduced to Victoria,

Australia as a biocontrol agent to manage invasive blackberry populations. However, it later
became a pathogen, spreading to non-target areas and creating unintended ecological impacts.

Notable Rust Pathogens in Australia

1. Puccinia antirrhini:

o Origin: Introduced to Sydney via contaminated seeds from Snapdragon plants

(Antirrhinum spp.).

o Impact: Evolved from a biocontrol agent to a pathogen.

2. Puccinia strum epilobii:

o Origin: Brought from New Zealand to Australia.

 3. Puccinia graminis f. sp. tritici (Stem Rust):

o Spread: Moved from Queensland to Southwestern Australia, overcoming the

barrier of a 1,000-kilometer desert.

4. Puccinia striiformis (Stripe Rust):

o Spread from Australia to New Zealand, demonstrating its capacity for trans-oceanic
dispersal.

5. Sugarcane Rust (Puccinia melanophila):

o Discovery in Australia: First reported near Cairns in 1978, signaling the pathogen’s
arrival in sugarcane-growing regions.

Sugarcane Rust Spread Across Continents

1. South Africa (1941):

o The rust pathogen was first identified in sugarcane plantations in South Africa,
marking the beginning of its documented spread.

2. Madagascar (1962):

o The pathogen crossed the Mozambique Channel to Madagascar, establishing itself

in the region’s sugarcane fields.

3. Réunion Island (1965):

o Spread to the island, likely facilitated by wind currents or human activities. The
pathogen thrived in the tropical conditions conducive to its lifecycle.

4. Mauritius (1964):

o Reached Mauritius, affecting sugarcane production on the island.

5. Australia (1978):

o First reported near Cairns, highlighting the pathogen’s ability to overcome

geographical barriers.
Rust Pathogen Spread in Europe and America

 Europe: Rust movement occurs from Romania to Scandinavia, and from Monaco to
Scandinavia, driven by local weather patterns.

 America: Rust pathogens move southward from the Great Lakes region to Texas and
Northern Mexico during the growing season, exhibiting striking parallels with the migration
of monarch butterflies. This similarity highlights how both the rust pathogen and butterflies
follow seasonal patterns and environmental cues, aided by wind currents.