Scientists identify genes that help cotton use less water

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Posted 7:42AM on Monday, January 7, 2002

ALBANY, Ga. - Scientists in Georgia and Israel have identified genes in cotton plants that could pave the way for drought-tolerant varieties. Andrew Paterson, a University of Georgia geneticist who headed the research, said the six-year, $280,000 study showed that by changing the genetics of cultivated cotton, scientists could give it traits that help wild cotton survive semiarid conditions. Cotton is a major crop in Africa, Asia, Australia and North and South America. All the cultivated varieties originated from wild cotton plants that grow naturally in such places as Mexico, Peru, Hawaii and the Galapagos Islands. ``Many of these genes were thought to have been lost in the process of domesticating cotton for high yields under well-watered conditions,'' said Paterson, who directs the University of Georgia Center for Applied Genetic Technologies in Athens. With additional research, scientists could theoretically incorporate the genetic changes into cultivated cotton within five years, and a conservative goal would be to increase cotton's water efficiency by 10 percent, he said. Paterson said researchers need to focus more attention on wild cotton varieties because they likely have additional drought-tolerant genes. ``This study drove home to me just how much variation is likely to exist in the wild cottons just how many opportunities there are to improve cotton in many ways,'' he said. ``That's an area that's been a little bit neglected. But there is a growing awareness in the industry that the breeding programs need to reach out to the wild varieties.'' Hugh Earl, a University of Georgia plant physiologist, estimates that Georgia cotton farmers could save 12 billion gallons of water annually, if cotton's water efficiency could be increased by 10 percent. That's enough water to fill 500,000 average-sized swimming pools. The resulting drop in irrigation also would save Georgia cotton growers $2 million a year, said Don Shurley, a University of Georgia agricultural economist who specializes in the crop. With the lowest cotton prices in 30 years, growers are searching for ways to reduce production costs. Irrigation is a major expense. Less irrigation also would help with water conservation, a critical issue with Georgia and much of the South in a four-year drought. Georgia paid farmers for the first time last year not to irrigate. Paterson's cotton study was funded by a U.S.-Israel Bi-National Agricultural Research and Development grant. He worked with plant physiologists Yehoshua Saranga at Hebrew University in Jerusalem and Daniel Yakir of the Weizmann Institute of Sciences in Rehovot, Israel. During field trials in Israel, Saranga grew two established varieties that had proven drought tolerant in tests. The varieties were crossbred, and the scientists jointly evaluated the water-efficiency of the offspring. Paterson then identified the specific genes that enabled the cotton to survive dry weather. ``In each of the two parents of the population we studied, we found different genes that confer improved quality and/or productivity under water deficits,'' he said. ``These can be 'reassembled' ... into a new genotype that is better than either parent.'' But water efficiency isn't as simple as changing a few genes, Paterson said. It involves multiple genes at different locations on the DNA molecule that act collectively to determine the characteristics of the plant, he said. Although not familiar with the specifics of the study, Andrew Jordan, director of technical services for the Memphis-based National Cotton Council, said such studies can improve the crop and shorten the time it takes to develop new commercial varieties. ``I consider this extremely important work,'' he said. ``With our current breeding programs for cotton, corn or whatever, it's easy to inbreed, where everything is a cousin to something else. We want to insure diversity of germ plasm to help plants resist diseases, insects or, in this case, to make them drought tolerant.''