New Corn Highly Resistant to Aflatoxin
A new corn line from ARS is the best
yet at naturally fending off aflatoxin, a fungal toxin that can be a threat to
food and feed safety. Commercial corn hybrids with strong aflatoxin resistance
are not now available. But as an important step toward this goal, ARS released
the new line, named Mp715, to seed companies and public research institutions.
In field tests, Mp715 had lower levels of both fungal infection and aflatoxin
contamination. Both qualities likely represent the most efficient and reliable
way to reduce aflatoxin in corn grain.
The ARS researchers are attempting to identify the genes responsible. Under
cooperative research and development agreements, ARS scientists plan to
evaluate 75 to 100 hybrids from the breeding programs of two seed companies
this summer. Some companies have already incorporated in their breeding
programs toxin-resistant germplasm that ARS released earlier.
Aflatoxin is produced by certain species of Aspergillus fungi. Last
year, corn aflatoxin levels soared in parts of the South because of record heat
and drought. Growers in Texas, Louisiana, and Mississippi experienced losses
estimated at $85 million to $100 million.
W. Paul Williams,
Host Plant Resistance Research Unit, Mississippi State, Mississippi; phone
Genetic Test Readied for Pig Disease
A faster, more reliable test may be on the way for a pig disease that costs
U.S. pork producers $17 million in lost weight and delays to market. Two
toxin-producing bacteria, Bordetella bronchiseptica and Pasteurella
multocida, are the culprits in atrophic rhinitis. Current diagnostic
methods take 5 to 7 days and aren't always reliable. The new test takes 3 days.
Since the disease spreads quickly in swine confinement houses, detecting the
bacteria sooner could cut losses.
The new test uses probes made from genetic material of the two bacteria. The
probes target genes found only in one or the other of the two microbes in
samples taken from swine. For the test, bacteria cultured from nasal or tonsil
swabs from a live pig are placed on a thin nylon sheet, which is subsequently
treated with the probes. If B. bronchiseptica is present, a pink color
will appear; if P. multocida, purple.
Karen B. Register,
USDA-ARS National Animal Disease
Center, Ames, Iowa; phone (515) 239-8275.
Enzyme Discovery May Help Plants and People
In plants and people, porphyrins are crucial natural pigmentsbut
troublesome if present in excess. In plants, porphyrins are precursors of
chlorophylls important to photosynthesis. In animals, including humans,
porphyrins carry oxygen through the blood. Recently, researchers with ARS and
Dartmouth Medical School found out how some plants may regulate porphyrins.
They also discovered a natural plant enzyme that deactivates these molecules.
The findings could someday lead to protection for people as well as crops.
In plants, chlorophylls convert the sun's light into food. Some herbicides
kill weeds by disrupting the manufacture of chlorophyll. Porphyrins then
accumulate to high levels, making the weeds fatally hypersensitive to light.
But such herbicides may also damage crops in the same field. A potential
solution: develop crops with high levels of the deactivating enzyme.
The discovery may also lead to new ways to treat porphyria. In people with
this genetic disease, cells don't properly turn porphyrins into heme, the
deep-red, iron-rich component of hemoglobin. Adverse effects can include
weakness, nausea, skin rash, and hypersensitivity to light.
Franck E. Dayan, USDA-ARS Natural Products
Utilization Research Unit, Oxford, Mississippi; phone (601) 232-1039.
Scientists Bullish on Peanutsfor Goats
A recent study done for USDA's Agricultural Marketing Service shows goat
meat stands to pick up in the marketplace because of the United States'
increasing cultural diversity. Now, scientists have found that forage peanuts
could make a nutritious fall pasture for goats in many areas of the Gulf Coast
region. For goats, the plants aren't grown for their nuts, but for nutrients in
their leaves. Scientists with ARS and Georgia's Fort Valley State University
used near infrared spectrometry to show that forage peanut plants are about
equal to alfalfathe usual goat foragein nutritional value. In fact,
goats may actually prefer peanut plants to alfalfa during the fall breeding
season. The results suggest that setting aside some peanuts for pasture might
be a profitable option. Fort Valley State operates a comprehensive program to
develop profitable year-round goat grazing systems.
William R. Windham, USDA-ARS Richard B.
Russell Agricultural Research Center, Athens, Georgia; phone (706)
Fort Valley State University,
Fort Valley, Georgia; phone (912) 825-6814.
"Science Update" was published in the
June 1999 issue of Agricultural