Drought Tolerance Found In Genes: January 1998 Soybeans Today

Soybeans Today January 1998

Drought Tolerance Trait Found in Genes

By Howell Medders

University of Arkansas researchers have found three potentially valuable "needles" in a "haystack" out of some 4,000 selections from the U.S. Department of Agriculture’s soybean genotype collection.

They are genes for a trait that makes soybean plants more drought tolerant, says Dr. Larry Purcell. There are now four known sources of such genes. The other is the 1950s vintage ‘Jackson’ variety.

A research team directed by Dr. Clay Sneller, soybean breeder and geneticist, and Purcell, a plant physiologist, screened the 4,000 selections of soybean plants over the past three years using a technique the researchers developed to measure a plant’s ability to fix nitrogen.

Soybean drought tolerance research is funded in part by producer check-off grants awarded by the Arkansas Soybean Promotion Board and by the United Soybean Board for work in Arkansas and three other states.

An early breakthrough in U of A drought tolerance research was the discovery in 1994 that nitrogen fixation is a weak link in the plant’s ability to produce seed under drought stress.

Jackson and the three recently identified unimproved plant introductions from the USDA collection have considerably better than average ability to fix nitrogen from the air under drought stress, Purcell said.

In another development, the researchers found that the Jackson trait for drought tolerance is heritable, which means it should be possible to move the trait into high-yielding varieties using conventional plant breeding methods.

Sneller has crossed the plants that possess genes for drought tolerance for nitrogen fixation with Arkansas-adapted, high-yielding varieties to begin the long process of combining the trait with other traits required of a commercial variety.

The breeding program will move much faster once a genetic marker is developed for rapid screening to detect the drought tolerance gene, Purcell said. The United Soybean Board has given preliminary approval for a grant to help fund development of such a marker by the four-state soybean drought tolerance research team.

Principal investigators in addition to Purcell and Sneller are Dr. Tom Sinclair at the University of Florida, Dr. Tommy Carter at North Carolina State and Dr. Randy Nelson with the USDA Agricultural Research Service in Urbana, Ill.

Soybeans Today January 1998
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