New Delhi, Aug. 21: Every day through the winter and spring each year, Subhash Chander Bhardwaj examines samples of a rust-like substance scraped off wheat plants by crop scientists from across India and mailed to him in paper envelopes.
Bhardwaj, a plant pathologist at a regional station of India’s Directorate of Wheat Research in Shimla, Himachal Pradesh, has the task of identifying each sample of rust caused by wheat-ravaging fungi that arrives on his desk from farms across the country.
His laboratory will sound the alarm if Bhardwaj or his colleagues ever detect Ug99, a fungus that emerged in Uganda in 1999 and has since spread, devastating wheat farms in parts of eastern Africa, migrating to Yemen, and turning up in Iran in 2009.
“Ug99 might travel with the wind or might be brought on an airplane,” Ronnie Coffman, professor of plant breeding at Cornell University in the US, told The Telegraph.
“Once established, it has the potential to behave like a biological firestorm and annihilate entire fields.”
The Shimla laboratory is among a network of institutions in 40 countries that are relying on surveillance, plant-breeding and fungicides to stay ahead in a race against Ug99 and other fungi that might pop up and threaten wheat.
“Finding and labelling each sample of rust is only one half of our task; the other is to help develop rust-resistant varieties of wheat,” said Bhardwaj, principal scientist at the Shimla regional station who has been tracking wheat rust for nearly 27 years.
Wheat-ravaging fungi cause yellow, brown or black rust-like blisters on the plants’ leaves and stems and disrupt grain production. Scientists believe that wheat and the fungi have co-existed since the domestication of wheat, and that some plants have evolved resistance to the fungi.
Every year, the Directorate of Wheat Research, headquartered in Karnal, Haryana, sends dozens of candidate resistant varieties of wheat developed through standard plant-breeding to an agricultural research laboratory in Njoro, Kenya, where they are tested against Ug99.
The scientists in Njoro have in the past three years screened more than 500 candidate resistant varieties from India.
“We now have about 40 wheat varieties with proven resistance to Ug99,” said Indu Sharma, head of the Directorate of Wheat Research. “Most of these new varieties promise the same yield as standard cultivated wheat varieties. Some have been handed over to farmers in India; others are in the pipeline.”
India’s annual wheat production has remained steady at over 90 million tonnes over the past three years but, crop scientists say, the risk of rust lingers in the backdrop of rising temperatures and poor soil nutrients that also threaten wheat productivity.
Scientists have identified seven variants in the Ug99 lineage with different levels of virulence and growth conditions. “The outbreak closest to India so far was one in Iran in 2009,” said Coffman, vice-chair of the Borlaug Global Rust Initiative, which held its technical workshop in Delhi this week.
“Fortunately, Iran deployed resistant varieties and fungicides and has eliminated it,” Coffman said. “But Ug99 persists in Yemen and wind currents have the potential to carry it across the Arabian Sea into India.”
The Borlaug Initiative is named after Norman Borlaug, the plant scientist who spearheaded the Green Revolution. The workshop in India marks the 50th anniversary of Borlaug’s arrival in India in 1963.
“My dad would have wanted us to hurry for we cannot be complacent when people are hungry and the threat of rust grows,” said Jeanie Borlaug, Norman’s daughter, who teaches Spanish at a US school and chairs the rust initiative.
Scientists have also been looking for genes in wheat and other plants that might help make wheat resistant to rust.
Evans Lagudah, a Ghana-origin scientist at the Council of Scientific and Industrial Research Organisation in Australia, has identified a rare mutation in ancient wheat varieties grown in the northwestern Indo-Gangetic plains. The mutation appears to confer resistance against three types of rust — stem rust, leaf rust and yellow rust — in the adult state of the plant.
“This is a phase when the plant is trying to set its seeds. This could be a significant addition to our armoury of rust-resistant genes,” Lagudah told this newspaper.