Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2009
Publication Date: 1/4/2010
Citation: Xu, M., Battacharyya, M.K., Palmer, R.G. 2010. Excision of an Active CACTA-Like Transposable Element from DFR2 Causes Variegated Flowers in Soybean [Glycine max (L.) Merr.]. Genetics. 184:53-63. Interpretive Summary: In soybean, flower color is controlled by several different genetic factors. Spontaneous changes in flower color are rare in soybean. The w4 flower color trait was shown to change frequently from white to white with purple spots or stripes to purple. This change, or mutability, was investigated genetically and biochemically. The w4 flower trait was located on the soybean genetic map. The chemical (enzyme) which caused this change was identified. The flower color trait and the enzynme always were associated. This information can be used by molecular biologists to understand flower color biochemical pathways in soybeans.
Technical Abstract: In soybean, the W4 locus is one of the loci that control anthocyanin biosynthesis of soybean flowers and hypocotyls. A putative transposable element was suggested to reside within or adjacent to this locus in the mutable line T322 (w4-m). In present study, the immature flower petals of six samples from five soybean lines carrying different W4 alleles, Harosoy w4 (w4), T321 (w4- dp), T322 (w4-m), and T369 (w4-p) and Harosoy (W4) were investigated for accumulation of anthocyanins and their precursors, and steady state transcripts of some of the genes involved in anthocyanin biosynthesis. The white petal sectors in T322 (T322w) and the purple petal sectors of T322 (T322p) were collected and examined separately. Results showed delphinidin or its derivatives were the main pigments in soybean flowers. The levels of these pigments were lower in flowers with less pigmentation. This was associated with low transcript levels or abnormal transcript products of the dihydroflavonol-4- reductase 2 (DFR2) gene. RFLP analysis, conducted with an F2:3 mapping population of a cross between cultivar Minsoy and T369 (w4-p), showed that DFR2 co-segregated with the W4 locus suggesting that the DFR2 gene is either located at the W4 locus or linked very closely to it. Based on phenotypic, biochemical and transcript data we conclude that DFR2 is located at the W4 locus.