Molecular Genetic Analysis of a Novel Recessive White Flower Gene in Wild Soybean

Cultivated soybean [Glycine max (L.) Merr.] flowers are either white or purple, whereas nearly all wild soybean (G. soja Sieb. and Zucc.) accessions have purple flowers. As a result, the soybean flower color phenotype has attracted the attention of plant breeders, biochemists, and population geneticists. Here, we report genetic mapping of a novel recessive white flower gene in YWS415, a wild soybean accession collected in Korea. The W1 locus, which is the major locus determining purple (W1) or white (w1) flower color, encodes flavonoid 3′ 5′‐hydroxylase in YWS415, which was more similar to the common W1‐type sequences than w1‐type sequences. Subsequent mapping results using an F2 population from a cross between the ‘Hwangkeum’ (purple flower) and YWS415 variants indicated that the white flower color was controlled by a recessive allele at the W4 locus that encodes dihydroflavonol‐4‐reductase 2 (DFR2). The w4 allele arose through insertion of a 5584‐bp nonautonomous transposon member of soybean GM_CACTA_33 family into the second intron of DFR2. It was designated as GM_CACTA_33_w4. Results from this study will enhance our understanding of soybean white flower inheritance and facilitate marker‐assisted selection for the antioxidative anthocyanins in soybeans.