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

Inheritance studies and molecular mapping identified a single dominant gene that conditions seed coat impermeability in soybean PI 594619. 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 can be 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 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.