Mapping QTLs for physiological traits associated with drought tolerance in rice (Oryza Sativa l.)

The present investigation mainly focused to study the physiological and molecular characterization of 101 Backcross Inbred Lines (BILs) of rice (BC1F5) for drought tolerance derived from the cross combination of Norungan // TKM9/ Norungan. The traits like photosynthetic rate, transpiration rate and stomatal conductance were observed using infrared gas analyzer (IRGA) and the population was phenotyped for other traits. Estimation of genetic parameters revealed that, among the physiological traits observed, the trait transpiration rate recorded higher value of heritability (0.28) and genetic advance (17.49). Association analysis recorded that, all the physiological traits studied under severe water deficit condition had high and significant positive correlation with plot yield. The trait photosynthetic rate had exhibited significant positive correlation with transpiration rate and stomatal conductance but recorded negative correlation with relative water content (RWC). Single marker analysis was performed with the genetic data and the trait mean values observed under stress condition. Among 167 SSR (microsatellite) markers surveyed, around 15 markers were identified and found to be linked to at least one of the investigated trait and many markers were reported to be linked with more than one trait. Characterization of Quantitative trait loci (QTLs) for drought tolerance in this study provides insight into an understanding of the mode of drought tolerance in rice and to perform MAS (Marker aided selection) aimed at the efficient pyramiding of favorable QTL alleles to improve drought tolerance in elite background of popular rice varieties.