Life cycle of wheat rust

 

Interesting story and life cycle of rusts

Brief Introduction:

Rusts are the devastating pathogens of wheat all over the world. These are known from ancient times due to their adverse effects on cereals resulting in poor yield. Ancient people considered plant diseases as the wrath of “god”. They celebrate festivals and offer sacrifices to please them. They thought that avoidance and control of diseases depend upon people doing thigs.

In 4^th century Romans suffered so much hunger due to destruction of cereals by rusts. To solve this issue, they created a separate “god” named as Robigus. To please their “god” Romans offered prayers and sacrifices, so that he would save them from deadly rusts attack. They established a special holiday on which they sacrifice their cows, dogs, and foxes to please the Robigus.

Life cycle of rusts:

Rust are obligate parasites and can not be cultured on artificial media.  Rusts produce five distinct fruiting structures consisting spores in them. Rusts which complete their life cycle in five stages are called macrocyclic fungi. Whereas those who only produce teliospores and basidiospores are called micro cyclic fungi.

Stages of rust

·         Teliospore

·         Basidiospore

·         Spermatia (Pycnioapsore)

·         Aeciospore

·         Urediospores

In some macrocyclic rusts spermatia and urediospores may be absent.  Following is the detail of spores with respect to their fruiting bodies. Only sexual spores are teliospore which produce basidium on germination after over-wintering. In basidium meiosis takes place and four haploid basidiospores are produced. They infect the host and produce spermatia and respective hyphae. Uredia produce urediospore which may infect and produce more urediospores. At maturity of host plant telia and teliospores are produced.

Stage	Fruiting body
Teliospore	Telium
Basidiospore	Basidium
Spermatia	Spermatium
Aeciospore	Aecium
Urediospore	Uredinium