New Corn May Improve Nutrition, Decrease Pollution
By Kathryn Barry
December 18, 1996
ABERDEEN, Idaho, Dec.
18--Corn kernels that hold less phytic acid, a natural compound, could mean
more nutritious animal feed and less potential for water pollution from manure,
a U.S. Department of Agriculture scientist
USDA's Agricultural Research Service
has applied for patent protection on low-phytic-acid corn developed by ARS
geneticist Victor Raboy. Under a cooperative research and development agreement
with ARS, Pioneer Hi-Bred International Inc. has bred the trait into its own
hybrids and is conducting tests. Commercial varieties may be only a few years
Without adequate phosphorus in the diet, people and one-stomached animals
such as hogs and chickens can have a higher risk of stunted growth and broken
bones, said Raboy, based at ARS'
National Small Grains
Germplasm Research Facility in Aberdeen, Idaho.
Corn, soybeans and other common feedstuffs have plenty of phosphorus. But
"animals with one stomach--including swine, poultry, fish and
people--can't absorb phosphorus from plant foods," he said. "That
causes both a nutritional problem and an environmental problem, as the
excreted, unused phosphorus can pollute lakes and streams." A story about
Raboy's research appears in the December issue of ARS' Agricultural
Farmers apply animal waste to croplands as fertilizer--enough each year to
fill railroad boxcars that would circle the earth according to University of
Kentucky estimates. Rain and other runoff can carry phosphorus-containing soil
to nearby lakes and streams. Algae thrive on the phosphorus, using up the
water's oxygen and choking out other aquatic life.
Raboy's low-phytic-acid corn enables one-stomached animals to extract the
grain's phosphorus--meeting their nutritional needs and thus excreting less of
the nutrient. This could also reduce the need for producers to give their
animals phosphorus supplements.
People rarely have a phosphorus deficiency, because meats, milk and nuts
are rich in forms of the nutrient that people can use. But developing countries
that depend on grain-based diets may find food applications for the research,
All the trouble seems to lie in the way plants store phosphorus. Instead of
storing the mineral in its pure form, plants bind up phosphorus in the phytic
acid compound. Animals with multiple stomachs, like cows and sheep, have
enzymes that break down phytic acid into usable phosphorus. One-stomached
animals lack the enzymes.
"We've isolated more than 20 mutations in corn, and others in rice and
barley, that cause the plant to store phosphorus in its inorganic, usable form
rather than as phytic acid," Raboy said.
"Some of the mutations reduce phytic acid by up to 95 percent, but at
that level some seeds might not germinate or the plants may yield poorly,"
he said. "Our most promising mutant reduces phytic acid by two-thirds
without reducing total phosphorus. So far we've found no problems with the
Preliminary tests by Pioneer indicate that the approach works.
"So far, the seeds seem to germinate well and in some cases have
yielded as well as our original hybrid," said David Ertl, Pioneer's
In other tests at Pioneer, low-phytic-acid corn from experimental hybrids
was fed to 300 chicks. Other chicks were fed normal commercial diets with a
known amount of phosphorus supplementation.
"The experimental hybrid corn seems to be performing just as we hoped
it would," Ertl said. Chicks fed the corn seemed to get adequate
phosphorus for growth and development, and excreted less phosphorus in the
manure, he noted.
Ertl estimates that a hybrid with the low-phytic-acid trait could be ready
for commercial production in 2 to 3 years.
Scientific contact: Victor Raboy, USDA-ARS National Small Grains
Germplasm Research Facility, P.O. Box 307, Aberdeen, Idaho 83210, phone (208)
397-4162; e-mail email@example.com.