Identification of QTLs for seed dormancy in rice (Oryza sativa L.)

With 3 figures and 3 tables ABSTRACT: Preharvest sprouting (PHS) can damage end-use quality in a number of cereal crop species. The trait is closely related to seed dormancy, for which there is known genetic variation in rice and other cereals. A set of 122 back-cross-inbred lines from the cross of ‘N22' (indica, strongly dormant) and ‘Nanjing 35' (japonica, no-dormant) were used to identify quantitative trait loci (QTL) for seed dormancy. Three QTL were detected on chromosomes 1, 2 and 3, and the proportion of the phenotypic variance explained by each was 18%, 8% and 7%. At all three loci, the dormancy-increasing allele was inherited from cv. ‘N22'. To map the chromosome 1 locus qSd-1 more precisely, an advanced back-cross (BC₆F₂) population was developed. The result of this population indicated that qSd-1 is in fact a pair of distinct, linked loci qSd-1-1 and qSd-1-2, which act additively to promote dormancy. Simple Sequence Repeats (SSRs) closely linked to each of the QTL identified should allow for the marker-assisted transfer of the dormancy shown by cv. ‘N22' for the improvement of the PHS of low dormancy cultivars.