BIOLOGICALLY BASED WEED MANAGEMENT: FUNDAMENTAL RESEARCH ON DORMANCY AND THE GENETICS OF WEEDS
Title: Seed Dormancy of Rice: From Natural Variation to Underlying Genes
Submitted to: Plant Dormancy Symposium
Publication Type: Abstract Only
Publication Acceptance Date: April 15, 2009
Publication Date: June 3, 2009
Citation: Gu, X., Ye, H., Liu, T., Anderson, J.V., Horvath, D.P., Suttle, J.C., Foley, M.E. 2009. Seed Dormancy of Rice: From Natural Variation to Underlying Genes. 4th International Symposium on Plant Dormancy Program and Abstract Book. Page 35.
This report updates our research progress on the natural variation of seed dormancy in rice (Oryza sativa). Ten quantitative trait loci (QTLs) have been associated with variation in seed dormancy between the weedy rice line SS18-2 and the cultivated rice line EM93-1. SS18-2 contributes alleles delaying germination at 8 loci, indicating domestication has eliminated an overwhelming majority of dormancy genes. Nine of the 10 QTLs also associate with one or more of the seed shattering, hull and pericarp color, awn, plant height, and flowering time traits, strongly suggesting that seed dormancy has co-evolved with the other adaptive and agronomic traits during domestication. Many of the QTLs interact with each other (epistasis) and/or with temperature during seed development to regulate phenotypic variation. The QTL qSD7-1 has been map-based cloned and identified as a transcription factor (TR), which has pleiotropic effects on seed dormancy, red pericarp color, and abscisic acid (ABA) accumulation in developing seeds. Microarray analysis identified about 170 candidate genes differentially expressed between the SD7-1 isogenic lines that could be assigned to anthocyanin and several other physiological pathways. These results provide further evidence that this TR may control red pericarp color and seed dormancy by regulating different pathways. The QTL qSD12 has been associated with the offspring (embryo or endosperm) tissue-imposed seed dormancy, and ABA accumulation in developing seeds. This QTL has been narrowed down to the genomic region containing a few predicted genes including a TR belonging to the same family as the SD7-1 dormancy gene.
Key words: Seed dormancy, weedy rice, quantitative trait locus, map-based cloning, transcription factor