Transposition of an Endogenous Transposable Element in Soybean

We have identified a highly active transposable element, Tgm9, from the W4 locus in soybean. W4 encodes dihydroflavonol-4-reductase 2 (DFR2) involved in the anthocyanin biosynthetic pathway. Plants with W4 have purple flowers; in the mutant (w4-m), where a transposon interrupts the gene, flowers are variegated. Early excision of the Tgm9 element from DFR2 results in purple flower (germinal revertant). We have demonstrated the utility of this element by cloning a fertility gene from a male-sterile, female-sterile mutant. The objective of this investigation is to study the nature of transposition Tgm9 in the soybean genome. We have identified revertants with purple flowers by growing a mutable line, T322 (w4-m), carrying the active Tgm9 in the DFR2 gene. We grew over 50 T322 (w4-m) mutable plants in the greenhouse to generate revertants. The progenies of individual branches of these plants were grown in the field and seeds of individual revertant plants were collected. We are using the genome walking technique to identify Tgm9 flanking sequences from 50 random mutants isolated from this mutant population. Results of this investigation will be presented.