Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 9, 2006
Publication Date: January 13, 2007
Citation: Foley, M.E., Gu, X., Kianian, S. 2007. Developing a Genetic System to Clone Seed Dormancy Genes from Red Rice. [Abstract] Weed Science Society of America Meeting. Presentation No. 147.
Seed dormancy is an adaptive trait that is critical to the persistence and survival of weedy plants in agroecosystems. Fundamental information on physiological, biochemical, and molecular regulatory mechanisms is lacking. Thus, the goal of our research is to identify mechanisms that regulate the quantitative aspects of natural variation in seed dormancy. This goal requires a well characterized genetic system to identify, map-based clone, and characterize individual quantitative trait loci (QTL), i.e., genes. Red or weedy rice (Oryza sativa) was selected because many resources are available for this species, its genome has been sequenced, and it is a serious weed. Dormancy is very strong for many weedy accessions and weak for modern cultivars. Dormancy in the dormant genotypes is mainly coat-imposed and is associated with other adaptive traits such as shattering, awn, black hull color and red pericarp color in weedy rice. Heritability for dormancy was much greater in weedy accession- than traditional cultivar-derived crosses. Seven dormancy QTLs have been identified from a weedy accession (SS18-2), and five of them tightly linked with one to three QTLs for other adaptive traits. Five generations of phenotypic selection alone for dormant extremes introduced five QTL dormancy alleles from the weedy accession to the background of a non-dormant breeding line (EM93-1). All seven QTLs interacted with each other through two or higher orders of epistases, and QTL analysis revealed that several QTLs responded divergently to the environment during seed development. To date, dormancy loci qSD1, 7-1, and 12 have been isolated as single Mendelian factors by marker-assisted selection. Preliminary data suggest that the gene underlying qSD7-1 is Rc, which codes for red pericarp in rice.