Soybean [Glycine max (L.) Merr.] have a variety of flower colors which are controlled by six different genes (W1,W2,W3,W4,Wm, and Wp). Among these genes, mutation in W3 gene causes near white flowers in the background of w4 genotype whereas the genotype W3w4 does purple throat flowers. Earlier studies showed that dihydroflavonol 4-reductase1 (DFR1) gene was closely linked to the flower color variants for W3 locus. In order to find out the W3 gene responsible for w3 phenotype, we first, studied the candidate gene Glyma14g07940 (DFR1) which is having 100% similarity with DFR probe sequence. Sequence analysis of DFR1 between W3 and w3 soybeans showed one base substitution in exon 6 of w3 mutant soybean resulting in one amino acid change in the amino acid sequence. However, comparison of amino acid sequences of DFR proteins from various crop plants showed that there is no functional change in the protein. Besides, the promoter analysis showed that, 311 bp of indel was traced in 5’-upstream promoter region of DFR1 gene in the w3 mutant. Here, we show that the near white or purple throat phenotypes in G. max is associated with existence or nonexistence of indel at 5’- upstream promoter region and low or high expression of DFR1, respectively. These results suggest that w3 phenotype may be caused by certain regulator of DFR1 gene located near or distant from DFR1 in G. max. In further study, we need to check the correlation between promoter indel with W3 expression level through GUS analysis.

• Gyu Tae Park(School of Applied Biosciences, Kyungpook National University)
• Jagadeesh Sundaramoorthy(School of Applied Biosciences, Kyungpook National University)
• Jeong-Dong Lee(School of Applied Biosciences, Kyungpook National University)
• Hak Soo Seo(Department of Plant Bioscience, Seoul National University, Bio-MAX Institute, Seoul National University)
• Jong Tae Song(School of Applied Biosciences, Kyungpook National University) Corresponding Author