Agricultural Research Service and University of
Illinois scientists have overcome a genetic quirk that makes some sweet corn
hybrids unable to handle herbicides that are often used to kill weeds in corn
fields. Click the image for more information about it.
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Researchers Identify Genetic "Fix" for Problem in Some Sweet Corn
Hybrids
By Jan Suszkiw
May 21, 2008 A genetic quirk discovered in some
sweet corn hybrids by Agricultural Research
Service (ARS) and University of Illinois
(UI) scientists is helping plant breeders make critical "repairs" to
the crop's herbicide-degrading machinery.
Several herbicides registered for use on sweet corn kill weeds but not the
crop, thanks to protective enzymes in corn that rapidly degrade the chemicals.
But some sweet corn hybrids aren't so lucky; they harbor a genetic defect that
impedes the enzymes, causing herbicides to linger in the plants, which suffer
stunted growth or other harm.
Now, with the defect known, plant breeders have begun using a technique
called backcrossing to eliminate this herbicide-sensitivity from germplasm used
to develop commercial hybrids. This should greatly reduce the risk of injury to
sweet corn from registered herbicides, notes
Marty
Williams, an ecologist in the
ARS
Invasive Weed Management Research Unit in Urbana, Ill.
Together with UI colleague Jerald Pataky, Williams elaborates on the problem
of herbicide sensitivity in sweet corn, and the benefits expected from
discovering its genetic cause, in two articles in Weed Science. One
article identifies the genetic cause of sensitivity to tembotrione, a new corn
herbicide available this year. The other articlewritten with UI colleague
Dean Riechers; Jon Nordby, formerly with UI; and
General Mills'
Joe Lutzdetails the genetic basis of sensitivity to several existing
herbicides.
The team found that a cytochrome P450 gene, which regulates metabolism of
nicosulfuron and bentazon, is also responsible for protecting corn from other
unrelated, P450-metabolized herbicides. By examining offspring plants derived
from a cross between a herbicide-sensitive sweet corn inbred and a
herbicide-tolerant inbred, they concluded that a defect in the
P450-geneor a very closely-linked P450 generesults in damage to
plants from five distinct herbicide classes.
The team's subsequent evaluations of 54 sweet corn hybrids and 40 inbred
lines found the faulty P450 gene is widespread in both processing and
fresh-market types of sweet corn grown throughout North America, but that it
can eventually be eliminated with selective breeding.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.