Nitrogen-Boosting Potential Found in SoybeansBy
January 30, 1998
A newly identified gene in soybeans could help farmers boost crop yields and
cut fertilizer costs.
Soybean plants' roots typically form nodules that become microscopic homes
for a special type of soil-dwelling bacteria called rhizobia. Inside the
nodules, these bacteria transform nitrogen from the atmosphere into ammonia, a
form of nitrogen that plants can use for growth. Ordinary soybeans can add about
40 pounds of usable nitrogen to an acre of soil.
Agricultural Research Service
scientists at the Plant
Physiology and Genetics Research Unit at Urbana, Ill., have now identified
the gene that regulates a process called "hypernodulation" in soybean
plants. A hypernodulating soybean plant produces hundreds of additional root
nodules, which opens the door to significantly greater nitrogen transformation
A typical commercial soybean cultivar generates up to 200 nodules on its
root system during the first month of growth, but a hypernodulated mutant
soybean can generate as many as 1,000 nodules during that time.
Typical soybean cultivars genetically "turn off" the nodule-making
machinery when signaled by a chemical produced in the shoot of the plant.
Scientists are now working to discover the chemical makeup of that signal and
how it tells the soybean plant when to "turn on" and "turn off"
its nodule-forming machinery.
If scientists can learn more about this chemical and how it interacts with
the hypernodulating gene, they may be able to regulate the trait in commercial
soybean lines, potentially reducing nitrogen fertilizer applications.
A complete story on this research can be found in the January issue of Agricultural
Research, the monthly magazine of the Agricultural Research Service. The
article is also on the World Wide Web at:
Scientific contact: James E. Harper,
Plant Physiology and
Genetics Research Unit, Urbana, Ill., phone (217) 244-6670, fax (217)