Resistant Wheat Plants Stave Off Hessian Flies by Starving Them

Results of a study conducted by researchers at the Purdue University and the U.S. Department of Agriculture (USDA) show that resistant wheat plants stave off attacks by Hessian fly larvae by essentially destroying the fly's midgut and its ability to absorb nutrients. Hessian flies cause considerable damage to wheat crops, with grain yields reduced as much as 20 bushels per acre with moderate infestation levels. Some wheat varieties have genes that can be deployed or used to combat the pest. Understanding their mode of actions, however, is necessary since the fly has overcome or is overcoming several genes initially deployed to protect wheat lines.

The researchers observed that within three hours, larvae feeding on resistant wheat had abnormal microvilli, fingerlike appendages that extend inward from the walls of the midgut to increase surface area for nutrient absorption. By six hours, the microvilli were nearly destroyed and the midgut was void of food. "Some chemical or compound they're encountering from the resistant plant is causing the microvilli to become disrupted, and it's happening very quickly," said Richard Shukle, researcher at the USDA.

Shukle and colleagues are suspecting that lectins might be one of the compounds responsible for the midgut disruption. Resistant wheat plants contain higher levels of proteins made by the Hessian fly responsive genes, called Hfr-1 and Hfr-3, than susceptible plants. Studies have shown that the protein made by Hfr-1 is a lectin, and the protein made by Hfr-3 is lectin-like.

For the original story, read http://www.purdue.edu/newsroom/research/2010/100208ShukleMidgut.html