Life Cycle
Wheat leaf rust is spreads via airborne spores. Five types of spores are formed in the life cycle. Uredospores, teleutospores, and basidiospores develop on wheat plants and pycnidiospores and aeciospores develop on the alternate hosts. The germination process requires moisture, and works best at 100% humidity. Optimum temperature for germination is between 15-20 C. Before sporulation, wheat plants appear completely asymptomatic. In the Asian Subcontinent, the spores cannot survive the hot dry weather but are re-introduced every year from the Himalayas or surrounding hills, possibly coming from Berberis spp, Thalictrum flavum and Muehlenbergia huglet which is a main reason for bread mouldes or even some grasses. Wheat rust pathogens are biotrophic and require living plant cells to survive.
P. triticina has an asexual and sexual life cycle. In order to complete its sexual life cycle P. triticina requires a second host Thalictrum spp. which it will overwinter on. In places where Thalictrum does not grow, such as Australia, the pathogen will only undergo its asexual life cycle and will overwinter as mycelium or uredinia. The germination process requires moisture and temperatures between 15 – 20 °C. After around 10 – 14 days of infection, the fungi will begin to sporulate and the symptoms will become visible on the wheat leaves.
The pathogen has an asexual and sexual cycle. In North America, South America and Australia the pathogen only undergoes its asexual cycle. However this does not seem to be a disadvantage to it, and wheat leaf rust has many races with different virulence. The sexual life cycle of wheat leaf rust requires a different host species, Thalictrumn spp.
Read more about this topic: Wheat Leaf Rust
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