Maysin Corn on Tap To Sour
By Jan Suszkiw
October 24, 2000
Corn earworms could soon find
themselves biting off more than they can chew.
Agricultural Research Service scientists
in Tifton, Ga., have developed four lines of inbred sweet corn whose silks have
a natural compound called maysin that can kill this caterpillar pest.
Commercial crops of maysin-producing corn--still a few years off--could help
farmers scale back their use of insecticides. In Florida, for example, sweet
corn growers sometimes spray up to 40 times per season to ensure the
unblemished, worm-free ears that consumers require. Nationwide, earworms cause
$100 million in yield losses and increased insecticide costs. And spraying,
while effective, can endanger beneficial insects.
The maysin in the new lines, on the other hand, is a natural defense
restricted to corn silks, where earworms start their feeding, said team leader
Neil Widstrom, with ARS
Genetics and Breeding Research Unit. Maysin also is only active in the
earworms gut and isnt toxic to humans and other animals.
In forced-feeding trials, a maysin concentration of less than one third of 1
percent of the silk's total fresh weight was enough to kill 50 percent of
earworms that digested it. In small- scale field trials this past summer, that
sensitivity translated to very little ear damage in the maysin corn, versus a
non-maysin control group that was not treated with insecticides.
Widstrom's team transferred the maysin trait into the sweet corn lines by
crossing them with a southern dent corn. They then back-crossed the lines to
the original sweet corn parent plant whose silks carry the trait. They also
selected plants with tight husks, which forces earworms to chew on the silks
before reaching the kernels.
Widstroms team is now using a genetic approach called marker-assisted
selection to speed development of high-maysin hybrids. Their work is part of a
cooperative research and development agreement that
Novartis Seeds, Inc.,
renewed with ARS in August.
ARS is the U.S. Department of
Agricultures chief research agency.
Scientific contact: Neil Widstrom, ARS
Crop Genetics and Breeding Research Unit, Tifton, Ga., phone (912) 387-2341,
fax (912) 387-2321, firstname.lastname@example.org.