Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: March 1, 2008
Publication Date: July 1, 2008
Citation: Gu, X., Foley, M.E., Anderson, J.V., Horvath, D.P. 2008. qSD7-1 is the first dormancy QTL cloned from weedy rice. Meeting Proceedings. Polish Journal of Natural Sciences. PLN ISSN 1731-3147 (Supplement 5/2008). Page 51. Technical Abstract: We answered a long-standing question about if the same or linked genes control the association between seed dormancy and grain color in grasses by map-based cloning a cluster of quantitative trait loci (QTL) for dormancy (qSD7-1) and pericarp color (qPC7 or Rc) from rice. A 2-cM region encompassing the two QTL from weedy rice (Oryza sativa) was introduced into the genetic background of a non-dormant line (O. sativa). We finely mapped this introgression region and selected rare recombinants, including the one intragenic to the predicted gene Os07g11020 as determined by the gene-based markers and confirmed by the DNA sequences. Progeny test for the recombinants demonstrated that the weedy rice-derived Os07g11020 allele has effects on seed dormancy, red pericarp color, and grain weight. The qSD7-1 underlying gene consists of 8 exons as determined by its full-length cDNA and a 14-bp deletion in exon 7 accounts for the natural variation in the above traits. We conclude that the above association arises from the pleiotropy of the qSD7-1 locus, and the selection for white pericarp-colored genotypes during the crop evolution has reduced the degree of seed dormancy and grain weight. In addition, the qSD7-1 dormancy gene contains a basic helix-loop-helix domain (OsbHLH017) and is annotated as a transcription factor. This research provides the first example showing that a naturally occurring mutant may regulate seed dormancy at a transcriptional level. We are identifying the physiological pathway(s) or gene network(s) differentially regulated by the qSD7-1 dormancy gene using the isogenic lines developed from the intragenic recombinant.