Location: Corn Insects and Crop Genetics ResearchTitle: Identification of an active endogenous transposon from the W4 locus in soybean) Author
Submitted to: Biennial Conference on Molecular and Cellular Biology of the Soybean
Publication Type: Abstract only
Publication Acceptance Date: 6/10/2008
Publication Date: 7/23/2008
Citation: Battacharyya, M.K., Xu, M., Brar, H., Grosic, S., Palmer, R.G. 2008. Identification of an Active Endogenous Transposon from the W4 Locus in Soybean. Biennial Conference on Molecular and Cellular Biology of the Soybean. Poster 68. Interpretive Summary:
Technical Abstract: In soybean [Glycine max (L.) Merr.], W4 is one of the loci that control anthocyanin biosynthesis in flowers and hypocotyls. A putative transposable element was suggested to reside within or adjacent to this locus in the mutable T322 line resulting in the w4-m allele. We have shown that the W4 locus encodes the dihydroflavonol-4-reductase 2 (DFR2). The w4-m allele in T322 is caused by the insertion of a CACTA-like transposable element, Tgmw4m, in the second intron of DFR2. Terminal inverted repeats (TIR) of the element are similar to those of other soybean transposable elements, e.g. Tgm family and Tgm-express1. We investigated footprints of several germinal revertant plants with purple flowers generated from a single progenitor mutable T322 plant. Distinct footprints were observed among the revertant plants. This result confirmed that excision of the element is responsible for gaining function of DFR2 among the germinal revertants with purple flowers. The w4-dp (dilute purple flowers) and w4-p alleles (pale flowers) were isolated as germinal revertants from the mutable T322 line. Both alleles mapped to W4. Sequencing of the promoters revealed that following excision from DFR2 intron 2, Tgmw4m inserted into the promoter of DFR2 in these functional mutant alleles. Two putative cis-elements, CCAAT motif and E-box (CACGTG) positioned at -1080 and -1068 were interrupted due to Tgmw4m insertion in these two alleles resulting in altered cell-specific DFR2 expression patterns in these functional mutants. Tgmw4m contains a transposes with high identity to that of En/Spm-type transposons isolated from maize. We investigated the extent of transposition events among the progenies of two sister progenitor T322 mutable plants. Approximately 40% of the families descended from a mutable plant contain one or more revertant plants with only purple flowers. We will discuss the applicability of this highly active endogenous transposable element in functional analyses of soybean genes.