Yahoo News 17 Mar 09;
MEXICO CITY (AFP) – A virulent strain of an old plant disease is threatening wheat production worldwide, experts warned in Mexico Tuesday, but they also reported progress in developing new varieties to try to beat it.
The dangerous new form of stem rust -- known as Ug99 for its discovery in Uganda 10 years ago -- has already spread across East Africa and the Middle East toward South Asia, according to research presented at the start of a four-day international meeting in Ciudad Obregon.
Ninety percent of the varieties planted around the world lack resistance to the reddish, wind-borne fungus that is already well established in Kenya, where it has decimated 80 percent of wheat in some areas, the experts said.
"That's the level you can expect," said Ravi Singh, a wheat geneticist and pathologist from the Mexico-based International Maize and Wheat Improvement Center.
Scientists led by Singh announced a breakthrough in their efforts to develop new varieties of wheat that are not only resistant to Ug99, but also produce more grain than today's most popular varieties.
Averting a crisis will require farmers to replace their existing varieties with resistant ones, even though they may not face an immediate threat, the experts said, pointing to a campaign underway in India to persuade farmers to switch.
"It's important to get something done before it hits," Singh told AFP.
Stem rust has plagued wheat farmers for thousands of years, but for the last 50 years it was largely under control thanks to resistant varieties developed by scientists led by pioneering US agronomist Norman Borlaug.
Their work, undertaken in Mexico, is credited with launching a "green revolution" that saved billions from starvation across the world and won Borlaug a Nobel Peace Prize.
"Our scientists are making incredibly rapid progress, but we should have no illusions: a global food crisis is still a distinct possibility if governments and international institutions fail to support this rescue mission," Borlaug said in a statement Tuesday.
Scientists gain in struggle against wheat rust
Yahoo News 17 Mar 09;
MEXICO CITY – Researchers are deploying new wheat varieties with an array of resistant genes they hope will baffle and defeat Ug99, a highly dangerous fungus leapfrogging through wheat fields in Africa and Asia.
"Significant progress has been made," plant geneticist Ravi Singh and collaborators said in a paper presented Tuesday to leading international wheat experts at a four-day conference on combating the re-emerged, mutant form of stem rust, an old plant disease.
Scientists still spoke of a potential agricultural disaster.
"A global food crisis is still a distinct possibility if governments and international institutions fail to support this rescue mission," Norman Borlaug, 94, the Nobel Prize-winning American agronomist, said in a statement.
The Borlaug Global Rust Initiative, an alliance of research institutions, organized the conference in Ciudad Obregon, northwest Mexico, where Borlaug did much of his research leading to the "Green Revolution" in farm productivity worldwide, including work that helped suppress stem rust a half-century ago.
More than 200 crop scientists from around the world were attending the workshop sessions, where three dozen papers were to be presented discussing the effort to crossbreed wheat varieties resistant to the new, virulent type of rust fungus.
It emerged in Uganda in 1999 — hence Ug99 — and has since spread east and northeast through Africa, and into southwest Asia, as far north as Iran. Global wind models indicate the crop disease may next spread into Pakistan, Afghanistan and India.
In some areas of Kenya, the reddish, wind-borne fungus has destroyed 80 percent of the wheat in farmers' fields, the Borlaug initiative's office said.
The researchers led by Singh, of the Mexico-based International Maize and Wheat Improvement Center, have engaged in "shuttle" crossbreeding of wheat varieties in the search for Ug99-resistant properties, developing varieties in test fields in Mexico and Syria, exposing them to Ug99 in Africa, returning them for refinement, then exposing them again in Africa.
Singh said they have produced new types that are not only resistant, but higher-yielding than today's most popular varieties.
The resistance comes not from one or two genes that convey immunity, but from an array of "multiple minor genes" that together achieve "near-immunity," the paper said.
Because Ug-99 mutated and overcame one and then another major resistance gene in Kenya, researchers hope a greater number of minor blockers — though each alone not a major defense — would prove a more complex challenge to the fungus.
Borlaug said Ug-99's ability to mutate quickly meant crossbreeding research must continue unabated, while governments and international institutions support stepped-up production and distribution of resistant wheat varieties.
