Eye-Color Gene May Help Scientists Slow Down a Wheat Pest

By Dawn Lyons-Johnson
September 9, 1998

In a botanical version of a relay race, wheat breeders have kept one step ahead of the Hessian fly, Mayetiola destructor, by breeding resistant varieties. Now, scientists at the Agricultural Research Service and Purdue University have made a genetic discovery about the fly that could help the breeders take a more commanding lead. ARS is the chief research agency of the U.S. Department of Agriculture.

Each year Hessian flies cause millions of dollars of damage to wheat crops. The female fly lays her eggs in unfurled wheat leaves. When the eggs hatch, larvae crawl down the leaves and feed on plant sap inside the leaf sheath of young wheat plants or at the nodes of the wheat head. This stunts the seedlings and can lead to lodging in heading wheat, greatly reducing yields.

But the fly is able to overcome each new resistant wheat variety within 8 to 10 years, making it necessary to introduce yet another resistant variety. Since the number of different genes for resistance in wheat to Hessian fly are believed to be limited, understanding how the fly overcomes resistance is essential.

Recently, the ARS and Purdue scientists discovered an important link between two Hessian fly genes: one for white-eye color and another that allows the insect to overcome a fly-resistance gene in wheat, called H13.

The close position of the two fly genes helps the scientists. They can use the white- eye gene to learn how the other gene--the one enabling the pest to overcome wheat's H13 defense--works. This will provide valuable information for breeders and allow scientists to modify genes for resistance in wheat so the Hessian fly can not overcome them.

The ARS scientists are based at the agency's Crop Production and Pest Control Research Laboratory at West Lafayette, Ind.

Scientific contact: Richard H. Shukle, entomologist, ARS Crop Production and Pest Control Research Laboratory, West Lafayette, Ind., phone (765) 494-6351, fax (765) 496-1219, rich_shukle@entm.purdue.edu.