Qtl Analysis And NIL Development Of Seed Dormancy In Rice Variety,4628

Seed dormancy (SD) is an important trait in rice because of its association with preharvest sprouting, which can damage end-use quality such as seed quality and yield in rice. With a set of recombinant inbred lines (RILs) derived from a rice cross of the variety996with weaker SD and4628with stronger SD. The seed dormancy was measured with the germination rate of seed harvested30days after heading in the2012and2013. A linkage map consisting of184DNA markers were constructed so as to determine quantitative trait loci (QTLs) for traits of seed dormancy. NILs with the genetic background of996and4628, respectively, which contain introgression chromosome segment harbor a QTL of SD from the donor RIL. The main research results are as the following:1. Total three QTLs related with seed dormancy cluding qsdl-1、qsdl-2and qsd7were detected in the two years experiments. Among them, qsdl-1and qsdl-2were detected in both experiment environments of2012and2013, which indicted that two QTL were expressed stable. The qsdl-1, which was located between RM297and RM6648on chromosome1, with the LOD score of4.25and2.55, explained7.50%and4.64%of the total phenotype variation in2012and2013, respectively. The allele of qsdl-1from the parent4628, which could reduce the seed germination rate of3.88%and5.96%, improved the seed dormancy. The qsdl-2, which was located in the interval markers of RM5389-RM315, with the LOD score of4.45and3.14, explained10.2%and7.10%of total phenotypic variation in2012and2013, respectively. The allele of qsdl-2from the parent4628also improved the seed dormancy, with the seed germination rate decrease of4.58%and7.44%. The qsd7, which was detected between RM21320-RM21327on chromosome7in2012, explained3.64%of the total phenotypic variation. The allele of qsd7from the parent4628, which increases the seed germination rate of6.60%, could weaken the seed dormancy.2. A series of BC4F1generation, which with the genetic background of996or4628, respectively, and a introgression chromosome segment from the donor RIL with different seed dormancy, were developed by successive backcross with mixed pollination. Ten lines, which with most of the genetic background similar with the parent of996/4628and harbor only one objective QTL, were screened form the BC4F1generation assisted selection by markers flank the target QTL and the no-target one. The objective near-isogenic lines with single seed dormancy QTL, could be developed by self-cross of the BC5F1plant that cross from the recurrent parent and the above BC4F1plant.The results in the present study, on one hand was beneficial to further fine mapping and cloning of the QTL related to seed dormancy, on the other hand the NIL with different seed dormancy was expected to be used in rice breeding program.