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multiple loci and epistases control genetic variation for seed dormancy in weedy rice ( oryza sativa )


作者單位:a Department of Plant Sciences, North Dakota State University, Fargo, North Dakota 58105b Biosciences Research Laboratory, United States Department of Agriculture-Agricultural Research Service, Fargo, North Dakota 58105Corresponding author:Michael E. Foley, 1605 Albrecht Blvd., USDA-Agricultural Res

【摘要】 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.

【關鍵詞】 multiple epistases variation dormancy


seed dormancy, the temporary failure of a viable seed to germinate under favorable conditions, is an adaptive trait that promotes the survival of many plants. rapid and uniform seed germination has been selected in crops, but a moderate degree of dormancy is desirable for cereals to resist preharvest sprouting (phs). preharvest sprouting is germination of seeds on the plant after maturation, but before harvest of the crop, when moist conditions prevail or untimely rains occur. it can cause a substantial loss of yield and reduce grain quality ( r inglund 1993 ). dormancy is a genetically complex trait controlled by polygenes with effects modified by the genetic background and environmental factors ( j ohnson 1935; a nderson et al. 1993 ). a major approach to determine the genetic architecture for seed dormancy is to dissect it into quantitative trait loci (qtl), such as in arabidopsis ( arabidopsis thaliana ), barley ( hordeum vulgare ), sorghum ( sorghum bicolor ), rice ( oryza sativa ), and wheat ( triticum aestivum; a nderson et al. 1993; o berthur et al. 1995; l in et al. 1998; l ijavetzky et al. 2000; m ares et al. 2002; a lonso -b lanco et al. 2003 ). quantitative trait loci analysis is also a prerequisite to clone and characterize genes that directly regulate seed dormancy and germination and to facilitate marker-assisted selection for resistance to phs in breeding programs.

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