A Preliminary Mapping Of QTLs For Drought Tolerance In Chinese Traditional Rice Variety, Dabaiqiu

Rice is an important food staple for millions of people globally. Drought, like many other environmental stresses, limits rice yield. Genetic improvent for drought stress tolerance in rice must deal with the quantitative nature of the trait, which reflects the additive effects of several genetic loci throughout the genome,each making a modest contribution towards the phenotype, through a variety of physiological mechanisms, perhaps conditionally in different environments.To facilitate the discovery of the Quantitative Trait Loci (QTL) for drought tolerance, we choose the DH population which is from a cross between DBQ (indica) and Maybelle (japonica) to construct a linkage map using 127 SSR markers. The map covers 1296.3.cM in the whole rice genome. After drought, plants were visually evaluated persistent four days. The degree of leaf rolling by each genotype was visually assessed and scored from 1 (DBQ) to 9 (Maybelle) according to the scale of IRR1. The DH population phenotype distributes continuosly as a single apex, from the drought tolerance identification to 255 double haploid lines. The result indicates that the leaf rolling presents quantative genetic character in the DH population because the phenotype distribution accords with normal school.Eleven QTLs were detected by the soft WinQTL Cartographer 2.0, which tow each were located on chromosomes 1, 5, 7, and 12 and one each on the chromosomes 2, 8 and 11. The phenotypic variation for leaf rolling degree explained by these QTLs ranged from 4.7% to 11.8%.The LOD values for these QTLs varied from 2.60 to 5.81. The additive genetic effects by the eleven QTLs varied from -0.724% to -1.293% and 0.521% to 0.934%. Qtlr12a on chromosome 12 was located between RM512 and RM3455, which was 3.0 cM far from RM512 and had the maximum LOD, 5.81. And the phenotypic variation for this QLT explained as 11.8%. Qtlr11 chromosome 11 was located between RM144 and RM224, which was on the minimum distance on the chromosome that was only 3.9 cM. Qtlrll was linked close with RM224 which was 0.3cM far from the QTL. And the phenotypic variation of qtlrll was 4.83. which LOD was 2.67. The additive genetic effects of qtlr1a, qtlrlb, qtlrll, qtlr12a and qtlr12b were negative, which indicated that the allele from Maybelle contributed DH population to improve drought tolerance. And additive genetic effects of qtlr2, qtlr5a, qtlr5b, qtlr7a, qtlr7b and qtlr8 were positive, which indicated that the allele from DBQ contributed DH population to improve drought tolerance.The result of this experiment is positively practical for MAS breeding of drought tolerance. We can aggregate the drought tolerance QTLs one plant rapidly by polyparental cross and backcross. It will save time to accelerate the breeding course. In addition, it is instructal and practical to select drought tolerance materials and construct the core germ plasm for drought tolerance.