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Research Magazine > ARCHIVE > Summer 01 > Article

Rust Resistant?
by Dan Rahn

Crop scientists constantly seek new resistance genes, only to have the pathogen change and overcome the resistance. But if USDA-ARS researcher Jeff Wilson has his way, pearl millet hybrids being developed in Tifton, Ga., will have greater durable resistance to rust, a fungal disease.

“Durable resistance is the holy grail for plant pathologists,” Wilson said. “The challenge is to breed for resistance that will remain effective. Some pathogens can change so quickly that by the time a new plant is released, its resistance is already ineffective.”

Wilson lamented that resistance treadmill as poor stewardship of nonrenewable genetic resources.

“If you identify genes for drought tolerance and breed them into adapted cultivars, you’ve fixed those [problems]. They can be used in any number of cultivars,” he said. “But resistance genes are different. By using a resistance gene in a way that allows the pathogen to change and make it ineffective, you’ve just lost that gene.”

To arrest the erosion of resistance genes, Wilson is researching an alternative way to use them. He calls it a dynamic multiline population strategy. “It more closely mimics the disease resistance of natural plant populations,” he said.

The theory is that in nature, truly superior resistance in plants didn’t come easy or fast. So instead of finding and using one or two resistance genes in a new plant, Wilson’s strategy is to find many such genes in many combinations, then concentrate them in an improved hybrid.

In effect, the plan is to put the toughness born of thousands of years of evolution into a plant that farmers can make a living growing.

Wilson has developed an experimental forage hybrid with this type of resistance. He’s in the process of developing the appropriate germplasm to use in a grain hybrid. He said he hopes to have it ready for release in 2008.


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