Updated February 1, 2021:
Soybean sensitivity to drought stress continues to be a major yield-limiting factor. In this project, we strategically combined our understanding of crop physiology with traditional and novel genetic approaches to develop high-yielding, drought tolerant soybean lines for US soybean farmers. Our efforts target the drought tolerance related traits of canopy wilting, canopy temperature, water use efficiency, and symbiotic nitrogen fixation. Our research is continuing to investigate the specific mechanisms underpinning genotypic differences for each of these traits at both the physiological and genetic levels. Using the resources from the national soybean germplasm collection we have identified genotypes with superior characteristics for each of these four traits using field-based measurements. Using genetic approaches, we linked the specific phenotypes with regions on the soybean genome that are underpinning these traits, providing the soybean community with molecular markers that can be used in breeding programs. We have verified many of these markers using biparental populations specifically developed for our targeted traits. In our germplasm improvement efforts, we have leveraged the phenotypic data and molecular marker information to strategically combine the four favorable traits into one genetic background. We are continuing to select and advance the most agronomically promising plants resulting from thousands of offspring derived from our crosses while at the same time generating more powerful genetic resources. We already have developed advanced germplasm using selection based on agronomic characteristics, seed germinability, and water use efficiency. This year, we have conducted yield trials in 11 different environments in Mississippi, Arkansas, Arizona, and Missouri that will allow us to make decisions about germplasm release and/or further testing in USDA regional tests. By strategically targeting physiological mechanisms and combining understanding of drought tolerance traits with genetic analyses and prediction of phenotypes based on genomic information, we are generating novel, drought-tolerant germplasm that will benefit all US soybean farmers.