Wheat plants that produce few or no lectins that bind to chitin are susceptible to Hessian fly larvae attack, she said. In addition, some virulent larvae can reprogram plant development so that cells in leaves and the base of the plant where the insects feed pump out nutrients favored by the insect. If this happens then even the weak, avirulent larvae on the same leaf have a chance to survive.
The researchers discovered that Hessian fly larvae reprogramming of resistant plant cells only occurs at sites where the insects attack. The study also revealed that increased numbers of larvae on a plant caused a parallel increase in lectin. This shows that wheat plant responses to these insects are localized and take less energy than a more global resistance response.
"Figuring out some of the ways that a plant is able to respond to insects with resistance will be useful in crop breeding programs," Williams said. "We're finding compounds like this chitin-binding lectin that don't cost the plant much to produce, unlike producing poisons and stronger walls. Those inducible defenses use a lot of a plant's energy that could be used toward growth and reproduction."
The scientists currently are looking for regulatory regions in Hessian fly-susceptible wheat genes that might act as vehicles to carry lectin or a toxin into plants to halt the virulent insects, Williams said. The regulatory regions, or promoters, would be from genes that the fly larvae ordinarily manipulate so plants will produce useful nutrients for the insect. Instead, the promoter would be hooked up to a lectin or toxin gene and inserted
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Source:Purdue University