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United States Department of Agriculture

Agricultural Research Service

Research Project: Development and Characterization of Soybean Germplasm, Curation of Stored Accessions, and Regional Evaluations of New Genotypes

Location: Crop Genetics Research Unit

Title: Identification of a single gene for seed coat impermeability in soybean PI 594619

Authors
item Kebede, Hirut
item Smith, James
item Ray, Jeffery

Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 13, 2014
Publication Date: N/A

Interpretive Summary: Hot weather during the filling of bean pods increases the occurrence of soybeans that are hard seeded. Hard seeded beans don’t take up water, which is associated with irregular and delayed emergence after the beans are planted. This has become a problem for soybean farmers who live in real hot places. Many of these hot areas are in the United States, especially in the midsouthern United States. Farmers in these hot areas recently started planting early varieties earlier in the spring in order to avoid late summer droughts. This improved their overall profit, but also lowered the overall value of their seeds for seed beans because hard seeds don’t emerge very well. So the objectives of our study were to help farmers by figuring out the inheritance of hard seededness so that improved varieties with tolerance to heat could be developed. A soybean line (PI 594619) from the USDA soybean germplasm collection was selected for the experiments because it had a lot of hard seed. Genetic studies indicated that the hardseededness in PI 594619 is controlled by a single major gene, with hard seed coat being dominant to non-hard seed coat. We named this gene Isc (impermeable seed coat). This finding will help scientists select new soybean varieties that do not become hard seeded when grown in extremely hot places.

Technical Abstract: High temperatures during seed fill increase the occurrence of soybeans with impermeable seed coat, which is associated with non-uniform and delayed germination and emergence. This has become an issue in soybean production areas with excessively high-temperature environments. The objectives of the present study were to investigate the inheritance of impermeable seed coat under a high-temperature environment in the midsouthern United States and to map the gene/s that affect this trait in a germplasm line with impermeable seed coat (PI 594619). Crosses were made between PI 594619 and an accession with permeable seed coat (PI 587982A) at Stoneville, MS in 2008. The parental lines and the segregating populations from reciprocal crosses were grown in Stoneville in 2009. Ninety-nine F2:3 families and parents were also grown at Stoneville, MS in 2011. Seeds were assayed for percent impermeable seed coat using the standard germination test. Genetic analysis of the F2 populations and F2:3 families indicated that seed coat impermeability in PI 594619 is controlled by a single major gene, with impermeable seed coat being dominant to permeable seed coat. Molecular mapping positioned this gene on CHR 2 between markers Sat_202 and Satt459. The designation of Isc (impermeable seed coat) for this single gene has been approved by the Soybean Genetics Committee. Selection of the recessive form (isc) may be important in developing cultivars with permeable seed coat for high-heat production environments. The single-gene nature of impermeable seed coat may also have potential for being utilized in reducing seed damage caused by weathering and mold.

Last Modified: 10/24/2014
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