Racing time to save world’s wheat from deadly fungus

CORNELL (US)—Ronnie Coffman’s search for clues to a highly virulent new strain of wheat stem rust took him to a little valley in India’s Nilgiri Hills. He wondered if the remote wheat breeding station there might play a role in the ongoing battle to fight the fungus to which only 10 percent of the world’s wheat varieties are resistant.

The deadly rust first appeared in Uganda in 1999, and since then its spores have traveled by wind to Kenya, Ethiopia, Sudan, and Yemen, and last year, it arrived in Iran. World food experts worry that the rust, known as Ug99, will continue east and infect wheat in Pakistan and India, which produce 15 percent of the world’s wheat and feed more than a billion of the world’s poorest people. To prevent such a crisis, plant breeders are racing against time to develop new Ug99-resistant wheat strains and distribute those seeds around the world.

“Wheat rust is always moving with the wind,” says Coffman, professor of plant breeding at Cornell University. “It never sleeps. Working together, the world’s wheat researchers can prevail against it, but no one, and no single nation, can do it alone.”

To coordinate international efforts against the new rust strain, Coffman directs the Durable Rust Resistance in Wheat (DRRW) project, a partnership of 15 institutions around the globe that was funded by almost $27 million to Cornell last year from the Bill & Melinda Gates Foundation. Between trips to Syria and Kenya, Coffman made a stop in India and traveled to the Indian Agricultural Research Institute’s Wellington substation on January 12.

“There are people in [wheat breeding research] stations everywhere that could contribute to addressing this problem, and we want to make sure they are mobilized,” says Coffman.

At the Wellington station, Coffman found a small staff highly knowledgeable about genes resistant to local strains of black (stem), brown (leaf), and yellow (stripe) rust. The staff showed him a large collection of wild relatives of wheat growing in research plots and explained that the facility was well set up to combine resistant strains with local agronomic wheat types, and that the climate in the cooler Nilgiri Hills allows for year-round wheat cultivation. They also informed him of their collaborations with biotechnology students and researchers at the Tamil Nadu Agricultural University in nearby Coimbatore, who were using molecular markers to locate and identify major or minor genes that play a role in rust resistance.

Coffman invited the station’s plant breeder, M. Sivasamy, to attend a meeting of wheat breeders this March at the International Maize and Wheat Improvement Center (CIMMYT) in northwest Mexico to further coordinate efforts.

CIMMYT’s wheat breeder Ravi Singh has bred wheat resistant to Ug99 at the plant’s adult stage. Seeds from these resistant plants were sent to 46 wheat research stations around the world, including the Wellington station. Indeed, in terraced fields on the hillsides above the institute’s main building, Sivasamy and colleague R.N. Brahma showed Coffman trials of recently planted foot-high resistant wheat. Sivasamy and Brahma eventually will cross the resistant wheat with local heat-tolerant varieties and stockpile the resulting plants’ seeds.

Meanwhile, Sivasamy helps track spores from the parasitic fungus using a hand-held global positioning system unit purchased by the DRRW and distributed by the Food and Agriculture Organization to wheat breeders. He and Coffman discussed further collaborations to bolster Indian farmers against the looming Ug99 threat.

The DRRW also is refining practices for screening wheat varieties for resistance; securing additional funding from new donors; continuing surveillance; breeding; identifying genetic markers; screening wild varieties for Ug99 resistance; using lasers to break adverse genetic linkages between agronomically positive and negative traits; and studying rice for key genes that might protect wheat from rust.

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