Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/26/2008
Publication Date: 8/1/2008
Citation: Gu, X.-Y., Tunipseed, E., Foley, M.E. 2008. The qSD12 locus controls offspring tissue-imposed seed dormancy in rice. Genetics. 179:2263-2273. Interpretive Summary: Seed dormancy is a key characteristic of weedy plants. In the course of research to map-base clone dormancy quantitative trait loci (QTL), we determined by genetic analysis that the QTLs qSD7-1 and qSD12 regulate dormancy through maternal tissues like the pericarp and offspring tissue like the embryo, respectively. This is the first genetic evidence for embryo imposed dormancy in weedy rice. Additionally, qSD12 was narrowed to a small region of the genome to facilitate cloning.
Technical Abstract: Seed component structures were grouped into maternal and offspring (embryo and endosperm) tissues to characterize a dormancy quantitative trait locus (QTL) for tissue-specific function using a marker-assisted genetic approach. The approach is devised to test if genotypic/allelic frequencies of a marker tightly linked to the QTL deviate from Mendelian expectations in germinated and non-germinated subpopulations derived from a segregation population of partially after-ripened seeds and was applied to the dormancy QTLs qSD12 and qSD7-1 in a nearly isogenic background of rice. Experimental results unambiguously demonstrated that qSD12 functions in the offspring tissue(s) and suggested that qSD7-1 may control dormancy through the maternal tissues. These experiments also provide the first solid evidence that an offspring tissue-imposed dormancy gene contributes to the segregation distortion in a mapping population developed from non-after-ripened seeds and, in part, to the germination heterogeneity of seeds from hybrid plants. Offspring and maternal tissue-imposed dormancy genes express in very early and late stages of the life cycle, respectively, and both work together providing the species with complementary adaptation strategies. The qSD12 locus was narrowed to the region of about 600 Kbp on a high-resolution map to facilitate cloning and marker-assisted selection of the major dormancy gene.