A wild weedy strain (i.e. SS18-2) of Oryza sativa L. was selected to investigate the geneticarchitecture underlying seed dormancy. A framework genetic map covering the whole ricegenome was constructed based on a backcross population (i.e. BC1 [EM93-1 (non-dormantbreeding line)//EM93-1/SS18-2]). Dormancy was determined by germination of seeds after1, 11 and 21 days after ripening (DAR). Six dormancy quantitative trait loci (QTLs), designatedas qSD4, 6, 7-1, 7-2, 8 and 12, were identified. The locus qSD7-1 was tightly linked tothe red pericarp colour gene Rc. In addition, the locus qSD4 was associated with an intervalimparting black hull colour. A QTL × DAR interaction was detected for qSD12, the locuswith the highest effect at 1, 11 and 21 DAR (R2 = 14%, 24% and 20%, respectively). Twoand more (i.e. three and four) orders of epistases were detected with four and all the sixQTLs, respectively. The higher-order epistases strongly suggest the presence of geneticallycomplex networks in the regulation of variation for seed dormancy in natural populations, and make it critical to select a favourable combination of alleles at multiple loci in positionalcloning of a target dormancy gene. Backcrossing techniques in combination with phenotypicand marker-assisted selection are being used to introduce the weedy rice-derived dormancylocus qSD7-1 into the EM93-1 genetic background to develop near isogenic lines for finemappingand positional cloning.
|Original language||English (US)|
|Title of host publication||Seeds|
|Subtitle of host publication||Biology, Development and Ecology|
|Number of pages||8|
|State||Published - Feb 27 2007|