Location: Plant Physiology and Genetics Research
Project Number: 2020-21410-007-12-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Oct 1, 2019
End Date: Sep 30, 2020
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: Physiological Mechanisms of drought tolerance. Determine trait stability over multiple environments in well-watered and rain-fed/dryland conditions and dissect mechanisms underlying the target traits. Objective 2: Identification and confirmations of putative drought tolerance loci. Confirm the potential of drought tolerance/trait markers previously identified by GWAS. Map and confirm putative QTLs in specific bi-parental mapping populations. Objective 3: Germplasm and population development. Develop and evaluate germplasm with multiple traits (stacking CW, CT, WUE, and NDFA) and/or multiple genomic loci for each trait (pyramid loci).
The research proposal will be collaborative efforts among the Co-PIs. Below are the ARS Maricopa location's experimental approaches for FY2020: Objective 1: Physiological mechanisms of drought tolerance: Objective 3: Germplasm and population development: In the proposed research, up to 10 F6:8 lines with high WUE and 10 with low WUE (all with high germinability trait) will be harvested in Mississippi in 2017. We will initiate irrigated yield trials of these 20 lines in 2018 (MS) coupled with WUE measures and seed quality traits (germination, protein, oil, etc.). Seed harvested from the 2018 trials will then be used in irrigated and non-irrigated comparative trials beginning in 2020 (AR, AZ, MO, and MS). The Maricopa, AZ location provides an ideal environment to evaluate the combination of drought and high temperature stresses in comparison to high temperature stress in the absence of drought (i.e., irrigated treatment). The best yielding, most WUE lines, will be identified for release. These releases will mostly be MG IV lines. Extreme lines may be targeted for more intense physiological evaluations.