A new gene that controls seed coat wrinkling in soybean

Seed coat wrinkling is a major factor affecting the germinability of soybean [Glycine max (L.) Merr.] seed produced in high-temperature environments, such as in the Early Soybean Production System of the midsouthern United States. Exposure of seed to high temperatures, coupled with alternating periods of wet and dry conditions, promotes seed coat wrinkling. This can predispose the seed to mechanical damage at harvest, further reducing germinability, and reducing the usability of the grain for seed beans. Previous studies identified a single recessive gene (shr) in a mutant line (T-311), located on chromosome 13 (linkage group F), which causes seed shriveling and seed coat wrinkling. The current study was undertaken to identify and genetically map new gene(s) that affect seed coat wrinkling. Crosses were made between a smooth-seeded accession (PI 567743) and a wrinkledseeded accession (PI 87623). The parents, F(1), F(2), and BC1 generations were phenotyped for seed coat wrinkling in a greenhouse in Stoneville, MS during the summer of 2006. Genetic analysis indicated that the wrinkled seed coat trait in PI 87623 was inherited as a single recessive gene. A test for allelism, conducted in the greenhouse with a segregating F2 population derived from T-311 x PI 87623, showed that the gene from PI 87623 is different from the shr gene in T-311. A field study of a larger population, derived from a reciprocal cross of the same parents, confirmed these results, but also suggested epistatic interactions between the genes. A linkage map was developed using 195 SSR and SNP markers on 168 F(2) individuals of the cross PI 567743 x PI 87623. Linkage analysis identified only one significant locus which was located on chromosome 5 (linkage group A1), confirming identification of a new gene that controls seed coat wrinkling in soybean. This study demonstrates genetic control of seed coat wrinkling, which offers the potential for selecting cultivars with less seed coat wrinkling for heat-stressed production environments.