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Dihydroflavonol-4-reductase (DFR) plays a crucial role in anthocyanin biosynthesis. In cultivated soybean [Glycine max (L.) Merr.], the W3 and W4 loci encode DFR1 and DFR2, respectively and are epistatic to each other. In this study, we discovered a new flower color variant of Glycine soja (L.) Merr., CW13133, which has pinkish-white flowers and investigated the genetic and molecular basis of the variation in flower color. We found that the W4 locus encoding DFR2 was responsible for the variation in flower color. Sequence analysis of the DFR2 gene of CW13133 revealed three single-nucleotide polymorphisms (SNPs). Among these, an SNP (T to C) at nucleotide position 2856 was noteworthy, since it led to a change in an amino acid residue (leucine to proline) at position 326 of DFR2. This amino acid substitution was located in a region that is highly conserved among different plant species. The new allele was designated w4-s1. A cleaved amplified polymorphic sequence analysis showed cosegregation of the w4-s1 allele with pinkish-white flowers. Interestingly, DFR1 was not expressed in the w4-s1 mutant, indicating that the W3 locus has no association with flower color variation. Based on a randomized comparative analysis using 10 different purple-flowered accessions of G. soja, we provide evidence for the nonassociation of DFR1 expression with total anthocyanin contents and flower color determination in G. soja. In conclusion, we found that the W3 locus in G. soja does not contribute to flower color determination and consequently there is no epistatic interaction between the W3 and W4 loci, as shown in G. max. [ABSTRACT FROM AUTHOR]

Increasing alpha-linolenic acid (ALA) in soybean [Glycine max (L.) Merr] seed oil is an important breeding goal in soybean because of its beneficial effects on human health. Seed oil of wild soybeans (G. soja Sieb. & Zucc.) generally has about twice the ALA concentration than seed oil from cultivated soybeans. Therefore, identification of wild soybean genotypes with high and stable ALA concentration over various growing conditions would be useful for breeding purposes. The objective of this study was to evaluate wild soybeans with high ALA for environmental stability. Fifteen wild soybean accessions with relatively high ALA concentrations (~170 to 200 g kg-1) and three check cultivars were evaluated across seven growing environments to determine the stability of ALA concentration. The ALA concentration of the wild soybean genotypes ranged from 169 to 191 g kg-1 with an average of 181 g kg-1. Seed of wild soybean genotypes had more than twice the amount of ALA than seed of the two cultivated soybeans, Williams 82 (72 g kg-1) and Daewonkong (78 g kg-1). CW13755 (185 g kg-1) and CW13943 (191 g kg-1) were the most stable across seven environments among all wild soybean accessions tested followed by CW13944 (191 g kg-1) and CW01022 (169 g kg-1) compared with the three checks. In conclusion, these environmentally stable wild soybean accessions with elevated ALA should be excellent germplasm sources to improve the ALA concentration in soy oil and to study the mechanism of ALA accumulation in soybean. [ABSTRACT FROM AUTHOR]