“With pre-breeding we’re trying to identify new sources of resistance. The long-term goal is to use molecular techniques -- not transgenic, but using conventional breeding to incorporate genes – to determine which genes are present.
“In the past, using conventional breeding methods, you might incorporate one major gene for resistance. Then, when you try to incorporate another you can’t tell whether you have (the gene), or not. That’s because the first gene is causing resistance. So, it’s hard to screen.
“However, now we have molecular techniques that tell us of the presence or absence of a gene.
“So, our long-term strategy is to stack those genes up. Theory tells us if we have several genes deployed together, the fungus won’t be able to overcome them. That will provide durable resistance.
“Of course, you won’t know if it’s durable until it endures. But that’s the theory we’re working towards.”
On resistance and genetics of the wheat being developed now…
“We’re currently relying on material that’s been under development at CIMMYT, the International Maize and Wheat Improvement Center based in Mexico. This is the organization that Norman Borlaug founded.
“Ravi Singh, CIMMYT’s lead bread wheat breeder and a trained plant pathologist, has been working on ‘minor’ gene resistance. This combines different sources of minor gene resistance with the idea of ending up with curable resistance.
“He’s been doing that for several years and it’s almost an art form. He’s able to recognize the type of pustule and morphological characteristics of the varieties that tell him that certain genes are present, or absent.”
Singh “appears to have good, resistant material. It’s holding up in our testing nurseries in Kenya, where the disease is epidemic. It’s held up there for the last several years.
“Those varieties, or breeding lines, that CIMMYT has produced have been distributed. Some 10 of them were distributed to six major countries and are under multiplication.
“The most urgent area for that is in Ethiopia. I’ve been there and seen the materials. They look excellent. Some are higher-yielding than the varieties the local farmers are currently growing. So, we’re optimistic about the farmers accepting them.”