Abstract :
Mapping QTLs with molecular markers can be very useful for plant breeders in agricultural genomics. The identification and introgression of QTLs for grain yield and drought tolerance indices is an efficient approach to improve the drought tolerance of rice varieties. In this study, QTLs controlling some traits associated with grain yield and drought tolerance indices were identified using 150 F8 lines derived from a cross between Sepidroud and Gharib, under non-stress and stress conditions. The genetic linkage map containing 12 ISSR polymorphic markers, 103 SSR, 1 IRAP marker, 11 REMAP markers and 16 combinations of ISSR markers covered 1005.2 cM of the rice genome and a mean distance between adjacent markers was 4.43 cM. In this experiment, two QTLs with main effects were mapped for SSI and YSI indices, three QTLs with main effects for grain yield under non-stress and stress conditions, TOL, STI, GMP, and YI, four QTLs with main effects for MP and HM. One epistatic QTL was mapped for grain yield under non-stress condition and STI index. The phenotypic variation explained by each main effect QTLs and epistatic QTLs ranged from 3.99 to 25.41% and 6.51 to 18.81%, respectively. Fifteen main effect QTLs, including, qGY9, qGY12a, qTOL4, qTOL5, qSSI5, qSSI6, qSTI9, qSTII2, qMP9, qGMP9, qGMP12, qHM12a, qYSI5, qYSI6, and qYI12a as the major QTLs controlling these traits can be considered in rice breeding programs for improving grain yield and drought tolerance after validation. The markers UBC816-2, (Tos2+UBC827)-4, (UBC826+HB12)-6, RM215 and RM5371 located near major QTLs could be used in MAS programs.
