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ARS Home » Midwest Area » Columbia, Missouri » Plant Genetics Research » Research » Research Project #435666

Research Project: Utilizing Genes from the Soybean Germplasm Collection to Mitigate Drought Stress

Location: Plant Genetics Research

Project Number: 5070-21000-040-21-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2018
End Date: Sep 30, 2019

Objective:
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 larger amounts of nitrogen. 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.

Approach:
Previous studies by this team identified at least 21 different genetic loci putatively associated with WUE. To confirm and refine these associations, an F6-derived recombinant-inbred line (RIL) population between soybean lines differing in WUE was developed. We intend to grow and phenotype the 200 lines of the RIL at three field locations: 1) Stoneville, MS , 2) Pine Tree Branch Station, AR and 3) Columbia, MO . The resulting phenotypic data collected the genotypic data from 2016, will be used to identify markers associate with WUE in the RIL population. Mapping WUE in this RIL population will confirm putative loci from our GWAS results and allow the targeting of specific genes along with the identification of associated molecular markers. Confirmation of important loci, identification of specific genes, and identification of molecular markers will be useful in current and future breeding programs for WUE. In combination with WUE experiment, an on-going breeding program combining high WUE and high germinability (HG) will be continued. HG under high heat conditions results in high quality seed (reduced disease, wrinkling, green seed, dockage, etc.). Agronomically- improved F6:7 breeding lines with high WUE and HG as well as breeding lines with low WUE and HG will be evaluated. Up to 10 F6:8 lines with high WUE and 10 with low WUE (all with high germination) will be used in the experiment. We will initiate irrigated and non- irrigated yield trials of these 20 lines coupled with WUE measures and seed quality traits (germination, protein, oil, etc.) in multiple locations. The best yielding, most WUE lines, will be identified for release. Combining improved germinability (and associated improved seed quality traits) with improved WUE would result in a soybean more suited to most of the production areas subject to periodic drought. In separate experiments, a soybean diversity panel consisting of 200 strategically selected genotypes will be grown at four locations under well-watered and rainfed conditions. All entries will be phenotyped for drought-related traits. Plasticity/stability for the traits will be assessed by two methods: 1) ‘static stability’ – the phenotypic variance of a genotype across environments and 2) ‘dynamic stability’ –the ratio of the slope of the regression for a specific genotype derived from its phenotype values in different environments and the slope of the regression for the population mean phenotype values in the different environments. From this we will gain a better understanding of the plasticity/stability of the different traits across the different locations.