Location: Plant Physiology and Genetics Research
Project Number: 2020-21410-008-001-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2021
End Date: Nov 30, 2022
A perceived weakening of the U.S. regulatory framework is causing end users to lower confidence in the sustainability of U.S. soy. A primary constraint on US soybean sustainability is the widely fluctuating yields due to drought. We have recently discovered MG 4 soybean genotypes from the germplasm collection that wilt more slowly, have higher water use efficiency (WUE), have cooler canopy temperatures, and fix large amounts of nitrogen than any germplasm previously discovered. Additionally, we have discovered molecular markers associated with multiple genes. In this research, we will evaluate the utility of these molecular markers in improving drought tolerance, determine the stability of these traits across extremely different environments, and pyramid favorable genes for each trait as well as stack these traits into improved germplasm lines for release. This proposal brings together a diverse group of scientists from the University of Arkansas, the University of Missouri, and the USDA-ARS labs at Columbia, MO, Maricopa, AZ and Stoneville, MS to leverage the discoveries from previous research by confirming the benefits of targeted traits for improving drought tolerance and providing a roadmap for utilizing the alleles for these four traits (Canopy temperature (CT) and wilting (CW), Water use efficiency (WUE), and nitrogen derived from the atmosphere (NDFA)) to enhance drought tolerance in improved soybean germplasm. Our specific objectives are: Objective 1: Introgress all four drought tolerance traits into a single genetic background using genomic selection using the lines from the germplasm collection with the most favorable alleles. Objective 2: Advance agronomically sound breeding lines from crosses between accessions with the four drought-tolerance traits and the elite, hub parent. Objective 3: Evaluation and identification of breeding lines with increased WUE for possible future release. Objective 4: Identify and confirm genetic markers for physiological traits relevant for soybean response to drought stress.
Objective 1 – We will develop lines combining all four of these drought-tolerant traits together in a single genetic background, and using the molecular marker data, we will select lines with predicted greatest drought tolerance. Objective 2 - We have over 200,000 F2 seed from crosses between accessions of the four drought-tolerant traits and the elite, hub parent that we will begin screening in 2020; selections made in 2020 will be advanced in 2022 based on agronomic characteristics and genomic selection. These selections will be fast-tracked for future germplasm releases. Objective 3 – We have four advanced breeding lines that have been selected for high WUE and seed heat tolerance/germination. Depending upon results of irrigated and rainfed experiments in 2020, the most promising lines will be entered into regional yield trials in 2022. Objective 4 – We will identify and confirm putative loci of drought tolerance associated traits and characterize trait stability/plasticity. We will map the genomic locations of plasticity alleles, which will provide insights into how plasticity interacts with different environments.