Quantitative Trait Loci (QTLs) Associated with Drought Tolerance in Vietnamese Local Rice (Oryza sativa L.)

One hundred and thirty lines of F-2 population derived from a cross between Khaunoongmo and Q5 were used to identify the quantitative trait loci (QTLs) related to drought tolerance in Vietnamese local rice in this study. The F-3 population was grown for phenotypic evaluation in the summer season of 2011 at the Center for Technology Development and Agricultural Extension, Hanoi, Vietnam under irrigated control. The standard evaluation system of International Rice Research Institution (IRRI) for drought sensitivity at vegetative stage was applied to evaluate the score of leaf rolling, leaf drying and plant recovery over the drought period. A number of SSR markers (765) were used for parental survey and of which 226 markers showed clear polymorphism (29.54%). These polymorphic markers were used to carry out genotyping F-2 population. Furthermore, three phenotypic traits under water deficit conditions were used for conducting a QTL analysis with Simple Interval Mapping (SIM) and Composite Interval Mapping (CIM) methods of QTL Cartographer 2.5 using 130 F-3, lines. Consequently, seven QTLs were detected on chromosome 4, 8, and 11: two QTLs for leaf rolling, three QTLs for leaf drying and two QTLs for plant recovery under water stress conditions. In addition, the logarithm of the odds (LOD) score of these QTLs ranged from 2.05 to 3.82, in which RM1359 linked to qLR-4 could explain 9.5% of leaf rolling variation, RM22654 linked to qLD-8-a explained 12.6% of leaf drying variation and RM22806 linked to qPR-8 explained 3.58% of plant recovery variation under drought conditions. Therefore, these consistent QTLs for leaf traits under stress might be useful for marker-assisted selection for rainfed rice improvement.