Why India need not worry over wheat pathogen Ug99

A team of scientists tracking the spread of plant diseases at Cambridge may have good and bad news for India.

The good news: a deadly fungus that was seen to cause widespread devastation in wheat fields in many parts of the world, particularly in East Africa, is unlikely to come in through a route which many feared that the pathogen would take.

The bad news, however, is that it may find alternative tracks to enter the country, which is among the largest wheat producers globally.

That probably explains why Ug99 — a deadly race of fungus puccinia graminis tritici (Pgt) — did not cross over to India despite it being present in Iran since 2006. Ug99 — named so because it was first detected in Uganda in 1999 — scared wheat breeders across the world as the particular race could attack Sr31, a stem rust resistance gene used in modern wheat breeding programmes.

The fungus causes stem rust that can severely hit yields as seen in the past in many countries in East Africa, West Asia and parts of Europe.

A team of plant epidemiologists from Cambridge University led by Christopher Gilligan used high performance computing, field surveys and high resolution meteorological data to simulate the routes that Ug99 and other deadly races of Pgt can take to land in wheat farms in other geographical areas.

“Our results show that the probabilities are generally low for Pgt spores reaching India and Pakistan from Iran and Afghanistan,” said Gilligan.

This is because there is only a very short time window available between the spore release and conditions suitable for infections of wheat in India and Pakistan, Gilligan, who is the main author of a paper in an issue of journal Nature Plants published on Monday.

Their number-crunching, on the other hand, showed that airborne spores travel across the Arabian Sea from Yemen, if there is a large epidemic. These spores travel at very high speeds and can survive up to three days, he said. An epidemic in Nepal too can be a cause of worry for India.

Suresh Bhardwaj, a principal scientist at Indian Institute Wheat and Barley Research, did not subscribe the view. India has one of the best surveillance programmes in the world for wheat rust, said Bhardwaj whose lab located at Shimla has been helping to develop wheat varieties which are resistant to rust diseases caused by different fungi.

“Ninety five per cent of wheat crops grown in central India, particularly in Madhya Pradesh and parts of Karnataka is resistant to this fungus. It will rather find it difficult to get a foothold here,” said an optimistic Bhardwaj.

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