Multiple loci and epistases control genetic variation for seed dormancy in weedy rice (Oryza sativa).
Weedy rice has much stronger seed dormancy than cultivated rice. A wild-like weedy strain SS18-2 was selected to investigate the genetic architecture underlying seed dormancy, a critical adaptive trait in plants. A framework genetic map covering the rice genome was constructed on the basis of 156 BC(1) [EM93-1 (nondormant breeding line)//EM93-1/SS18-2] individuals. The mapping population was replicated using a split-tiller technique to control and better estimate the environmental variation. Dormancy was determined by germination of seeds after 1, 11, and 21 days of after-ripening (DAR). Six dormancy QTL, designated as qSD(S)-4, -6, -7-1, -7-2, -8, and -12, were identified. The locus qSD(S)-7-1 was tightly linked to the red pericarp color gene Rc. A QTL x DAR interaction was detected for qSD(S)-12, the locus with the largest main effect at 1, 11, and 21 DAR (R(2) = 0.14, 0.24, and 0.20, respectively). Two, three, and four orders of epistases were detected with four, six, and six QTL, respectively. The higher-order epistases strongly suggest the presence of genetically complex networks in the regulation of variation for seed dormancy in natural populations and make it critical to select for a favorable combination of alleles at multiple loci in positional cloning of a target dormancy gene.
Gu
Xing-You
XY
Department of Plant Sciences, North Dakota State University, Fargo, North Dakota 58105, USA.
Kianian
Shahryar F
SF
Foley
Michael E
ME
D000483:Alleles; D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D004843:Epistasis, Genetic; D008040:Genetic Linkage; D014644:Genetic Variation; D018745:Genome, Plant; D018525:Germination; D012275:Oryza / Q000235:genetics*; D040641:Quantitative Trait Loci; D012639:Seeds / Q000235:genetics / Q000502:physiology*