Influence of PTGS on Chalcone Synthase Gene Family in Yellow Soybean Seed Coat

Most commercial soybean varieties have yellow seeds due to loss of pigmentation in the seed coat. We previously showed that inhibition of seed coat pigmentation in yellow soybeans is controlled by post-transcriptional gene silencing (PTGS) of chalcone synthase (CHS) genes. Soybean CHS genes are composed of at least eight members, CHS1-CHS8. In this study, we compared the steady state mRNA level of each CHS member in the seed coat between a yellow soybean cultivar displaying CHS PTGS and its pigmented seed coat mutant in which the CHS PTGS is abrogated. Northern hybridization analysis suggested that in the pigmented seed coat, the transcripts of CHS7 and CHS8 were abundant among the total CHS transcripts, whereas those of other CHS members (CHS1-CHS6) were less abundant. Reverse transcription and subsequent real time PCRs using member-specific primers revealed reduction of the amount of mRNA of most CHS members in the non-pigmented seed coat of the yellow soybean as compared to the pigmented seed coat of the mutant, indicating the influence of PTGS on the CHS gene family.