Ian Mannix
Digital News Editor
Researchers in Australia have developed a rapid test which can identify genes that can trigger resistance to stem rust disease in wheat, which might lead to much more timely and effective response for the grains industry.
The CSIRO’s Dr Peter Dodds describes the new tool as: “a breakthrough in molecular plant pathology” enabling new genetic strategies to “safeguard crop production and disease management in Australia and abroad.”
A paper, ‘Pooled effector library screening in protoplasts rapidly identifies novel Avr genes’ was published in Nature Plants this past February
The development comes years after the group’s work on stem rust began. The initial research was funded by the philanthropic trust 2Blades, after the disease devasted crops in Africa over a decade ago. Dodds says rusts are a “persistent threat to global food security.”
However a new tool identifies genes which can induce natural resistance to the rust pathogen, which are referred to as “effector genes.” These pathogen genes encode proteins that normally suppress plant immune responses. However, if the plant recognises these pathogen proteins, they can activate plant defence mechanisms and stop widespread infection.
“The resistance is genetically tractable,” Dodds says. That means it’s amenable to genetic modification, using bioengineering. That’s not always the case, says Dodds.
“There are some diseases for which there’s just very little resistance around, there’s not much you can do. But there is a lot of resistance around for wheat rust, although not all of it is useful.
“So it’s a question going through which ones are available? Which ones are actually going to be useful?
“I think the genetics of the rust resistance is more tractable, for example, for us in wheat, than say something like septoria blotch, where very little resistance is around so it’s hard to do breeding because it’s hard to find any resistance.
Can we eradicate wheat rust?
The new tool speeds up the process dramatically.
“We did one experiment, which took a few weeks, and found the two we already had, that took 10 years previously, and then we found two more. Since then, we’ve found another five or six.”
It took more than a decade to identify two of the rust genes that can trigger resistance in wheat. The grains industry can then use that information to breed for higher rust resistance in new varieties by selecting for lines that respond to these rust proteins. That’s a time of maybe 15 years to build a resistant crop.
“The breeding process is very long, but we can now go back immediately and say to breeders, look in your breeding pipelines, and select lines which (we know) are better than others.”
Dodds is part of a team of about 25 scientists at CSIRO headquarters in Canberra. He’s been working on disease resistance for 25 years.
“When I started a lot of the work we were doing was very kind of fundamental in nature. It was just trying to understand well, how does disease resistance work in plants? But I think in the past 15 years it’s been a lot more applied research, mainly in wheat and wheat rusts.”