Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 18, 2007
Publication Date: December 1, 2007
Citation: Gu, X., Foley, M.E., Suttle, J.C., Anderson, J.V., Horvath, D.P., Kianian, S.F. Seed Dormancy in Weedy Rice (Oryza sativa L.). Meeting Abstract. National Wheat Genomics Conference Abstracts. Page 24, P10.
Seed dormancy has been associated with grain color in wheat and rice, with the red colored genotypes being more dormant than the white colored ones. However, it remains uncertain if the association arises from pleiotropy or linkage. We introduced a segment of chromosome harboring a cluster of quantitative trait loci (QTL) for seed dormancy (qSD7-1) and pericarp color (qPC7) from weedy into cultivated rice to clone and characterize their underlying gene(s). High-resolution mapping narrowed the QTL to the same locus of Os07g11020 (a predicted transcription factor) and obtained a rare recombinant intragenic to the transcription factor. Sequence comparison for the 6445-base pair (bp) region identified 33 point mutations between alleles from the weedy and cultivated lines and that intragenic recombinant retains a segment of 2000 bp from the weedy rice. A pair of dormant and non-dormant isogenic lines was developed from the recombinant and these lines differed in seed dormancy, pericarp color (red vs. white), grain weight, and abscisic acid (ABA) content at about 10 days of seed development. The transcripts of the dormancy gene were detected in both seed and leaf tissues from the isogenic lines; sequence comparison between the genomic DNA and the full-length cDNA identified eight exons and the 14-bp deletion in exon 7 that accounts for the molecular lesion for the aforementioned natural variation. We conclude that the above association in rice is a pleiotropic effect of the predicted transcription factor and the dormancy allele cannot be used to improve white pericarp-colored varieties for resistance to pre-harvest sprouting. This research also suggests that the qSD7-1 underlying gene may regulate the natural variation in seed dormancy and pericarp color by ABA- and pigment-related physiological pathways, respectively, and may have other effects on the traits expressed in the vegetative tissues.