Mapping QTL for Seed Dormancy in Weedy Rice

The objective of the study is to dissect the genetic basis of seed dormancy. The weedy rice “Ludao” (Oryza sp.) with strong seed dormancy was crossed with the rice variety Akihikari (O. sativa subsp. japonica) and 215 lines of BC1F1 were developed for QTL mapping. A total of 4 quantitative trait loci (QTLs) associated with seed dormancy were located on chromosomes 1, 2, 6, and 6, explaining 7.8, 7.1, 5.5, and 4.5% of the overall phenotypic variance, respectively. The QTL, qSD-2, on chromosome 2 appeared to represent a novel source of genetic variation for seed dormancy. A multi-way analysis of variance indicated that the gene action of the 4 QTLs was additive. There was significant negative correlation between the germination rate and the flowering time. A single heading date QTL was identified to be either pleiotropic or linked to a seed dormancy QTL on chromosome 6, thereby accounting for the observed correlation between seed dormancy and flowering time.