AMID the global food crisis, there is finally some good news. Scientists meeting in Ciudad Obregón, Mexico, this week say they have developed new varieties of wheat resistant to the Ug99 strain of stem rust fungus that is threatening the world’s food supplies. The race is now on to get the wheat into the world’s breadbaskets before Ug99 spreads further.
Stem rust, one of the deadliest wheat diseases, has not been a global problem since the 1960s, when three genes for rust resistance were bred into high-yielding wheat varieties by scientists at , a laboratory of the green revolution in Mexico that now belongs to the . Virtually all of the world’s wheat, which supplies some 20 per cent of humanity’s calories, now depends on these genes.
The genes kill the fungus, so if just one mutant spore becomes immune to them it will thrive while competing spores die, says Hans-Joachim Braun, head of wheat breeding at CIMMYT. That happened in Uganda in 1999. The fungus, Ug99, broke out of East Africa in 2007, has reached Iran and now threatens south Asia.
Advertisement
An was funded by the Bill and Melinda Gates Foundation in April 2008 and now Ravi Singh, head scientist at CIMMYT, says they have found a complex of genes that should be harder for the fungus to evade.
In a year of frenzied international breeding programmes, CIMMYT and national labs cross-bred a wheat variety called Kingbird – which carries the new gene complex – with high-yielding varieties of wheat adapted for different regions, and tested the results against Ug99 in infected regions of Africa. Besides resisting Ug99, says Singh, the new breeds yield more grain than the varieties that farmers now grow.
“As well as resisting stem rust, the new wheat yields more grain than the wheat farmers currently grow”
The researchers have also dodged a financial crisis. When the Gates’s programme was launched, 91av reported that the US government was about to stop essential funding for CIMMYT. After widespread protests, says Braun, the US restored CIMMYT’s funding from another budget, then found an additional $5.5 million for the development and production of Ug99-resistant seed.
It is not enough to have wheat breeds that resist Ug99, however. Someone must grow enough seeds of those breeds to replant fields if the rust invades. Farmers won’t grow experimental varieties without a guaranteed buyer, but the US funds have allowed CIMMYT to pay for seed crops in Bangladesh, Nepal, Pakistan and other countries in Ug99’s path.
It will still take two to three years to generate enough seed for countries at risk, says Braun, so it is now a race against time, wind and spores.
