Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 5, 2007
Publication Date: April 1, 2008
Citation: Foley, M.E., Gu, X., Anderson, J.V., Horvath, D.P. Seed Dormancy in Weedy Rice (Oryza sativa L.). Symposium Proceedings. International Symposium on Pre-harvest Sprouting in Cereals, Mendoza, AR, November 5-9, 2007, P.20. Available: http://www.agro.uba.ar/epg/sprout2007/summary-PHS.pdf.
We developed weedy rice (SS-18-2) as a genetic system to investigate mechanisms regulating natural variation in seed dormancy. This included introduction of a set of quantitative trait loci (QTL) enhancing seed dormancy into the non-dormant genetic background of cultivated rice (EM93-1) to clone and characterize the underlying genes. We focused on qSD7-1, the QTL associated with the red pericarp/testa color trait. A high-resolution map and a progeny test for seed dormancy of the selected recombinants demonstrated that qSD7-1 is the Os07g11020 locus, a predicted basic helix-loop-helix (OsbHLH017) transcription factor. We obtained one rare intragenic recombinant for the Os07g11020 locus and developed isogenic lines (IL) for the dormancy and non-dormancy alleles. The genomic region for the predicted gene was cloned from wild and mutant parents and the dormant IL. A 14-bp deletion in the segment accounted for the natural variation in seed dormancy, which was also confirmed with cDNA sequences cloned from seed and leaf tissues of the dormant and non-dormant IL. We conclude that qSD7-1 has pleiotropic effects on seed dormancy, red pericarp color, and grain weight. The pleiotropic effects enhance the adaptability of weedy rice, but prevent this dormancy gene from being used to improve resistant to pre-harvest sprouting in white pericarp-colored varieties.