Maysin Rich Corn Varieties Identified

WASHINGTON - May 9/02 - SNS -- USDA researchers have two lines of dent corn which produce silks rich in maysin, a chemical which stops caterpillars which eat the silks from growing. In this way it acts like a natural repellent.

Researchers say crossing the maysin-rich corn with elite commercial lines should enable plant breeders to eventually provide farmers with hybrids that withstand attack by corn earworms, believes Neil Widstrom, a geneticist at ARS' Crop Genetics and Breeding Research Unit in Tifton, Georgia.

Farmers' main defense against the caterpillar pest in sweet corn is to spray the crop with insecticides, sometimes as often as 30-40 times a season. But a crop of maysin-rich corn could cut farmers' insecticide use by about half, scientists predict.

Maysin works by binding up certain proteins in the earworm's gut so that it cannot grow. Humans, other animals and beneficial insects face no such danger, according to Widstrom.

He and colleagues used conventional plant breeding and back-crossing techniques to produce the high-maysin corn. First, they selected plants whose silks produce enough maysin to stop earworms from feeding after just a few bites. Second, they also chose plants with tight husks so the pest is forced to chew the silks before the kernels, which don't contain maysin. The researchers also showed it's possible to transfer the high-maysin trait from dent corn to sweet corn.

Registration of EPM6 (a high-maysin, purple-kerneled dent corn) and SIM6 (a yellow- kerneled dent corn) in the November-December issue of the journal Crop Science marks 23 years of maysin research by scientists at ARS labs in Berkeley, California; Columbia, Missouri; and Tifton in cooperation with the University of Georgia, notes Widstrom.