|Carter Jr, Thomas|
Submitted to: American Seed Trade Association Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/20/2006
Publication Date: 3/5/2006
Citation: Carter Jr, T.E., Orf, J., Purcell, L., Specht, J., Chen, P., Sinclair, T., Rufty, T. 2006. Tough times, tough plants - new soybean genes defend against drought and other stresses. American Seed Trade Association Conference Proceedings.
Interpretive Summary: Drought is the biggest ‘profit stealer’ in U.S. soybean. Why is this so? Two simple facts tell the story: 1) drought occurs often in soybean production areas (somewhere every year), and 2) most U.S. soybeans are not irrigated (the states of MS and NE being notable exceptions). When drought strikes, farmers have few remedies at their disposal which can be brought to bear. For problem weeds, farmers can spray. For nematodes or phytophythora, farmers can choose resistant varieties. For drought, farmers just watch the crop suffer while dry weather steals away yield. In 1980, no one in the world could point to any soybean genotype and say, ‘this plant has agricultural drought tolerance’. The starting point in drought research was to search for soybean types which differed for seed yield and water response in the field under drought. The USDA soybean germplasm collection held a few thousand exotic accessions of group IV through VIII maturity in 1980’s. Field testing revealed that one of these accessions from Japan, PI 416937 looked visually appealing in the field when literally everything else had wilted. This was the first slow-wilting type identified. In the last 4 years, the search for slow-wilting exotic soybean types has been expanded to include the Midwest. In MN and NE researchers have identified have several new exotic types that appear to be slow wilting and/or high yielding under stress. These new discoveries are the basis for current field breeding of drought tolerance.
Technical Abstract: Public-sector drought-tolerance research has been a nationally coordinated effort for the past several years in the USA. Coordination is an important operational word in drought-tolerance studies. In an area that was formerly best known for its lack of progress, coordination has turned out to be THE missing key responsible for current research success. There are two primary reasons that coordination is so beneficial in drought tolerance research. The first is that drought tolerance is complicated and requires networking across scientific disciplines. The second is that drought occurs in different regions of the USA each year and requires networking across geographical areas to study. The public sector ‘Team Drought’, as it has come to be called, coordinates at both these levels. Team Drought includes three kinds of scientists: physiologists (to understand and measure drought tolerance), breeders (to make the genetic crosses and field test them) and molecular geneticists (to tag genes in breeder populations using DNA markers). Team Drought also includes scientists spread geographically over the soybean growing area. The details of Team Drought’s successes will be provided later in the presentation. The take home message for agriculturalists is that the drought team has 1) discovered multiple genetic sources of drought tolerance, 2) DNA mapped several of the genes involved in drought tolerance, and 3) transferred this technology to industry. Industry appears to be using genes and germplasm derived from this public research effort. The team has also made important advances in combating other, often related, environmental stresses. Most prominent among these environmental problems are salt injury, and Fe and Mn deficiencies.