QUANTITATIVE TRAIT LOCI (QTLs) MAPPING WITH SUBMERGENCE TOLERANCE IN RICE (Oryza sativa. L) IN THE MEKONG DELTA

SSR technique combined with selective genotyping was used to map quantitative trait loci (QTLs) associated with submergence tolerance in rice. One hundred sixty-eight lines (BC2 F2 ) derived from the cross of OM1490/IR64Sub1 were evaluated for submergence at flowering. Microsatellite map of this population was used with 194 markers to detect the linkage to the target traits. The map covers 2,008 cM with an average interval of 10.97 cM between marker loci. Markers associated with submergence tolerance were located mostly on chromosomes 1, 2, 3, 8, 9, 11 and 12. QTL mapping was used to determine effects of loci associated with submergence tolerance traits: Plant height, tillers/panicle, unfilled grains/panicle, 1000 grains weight, yield and plant survival during flowering. We also mapped QTLs for morphological attributes related to submergence tolerance. Chi-square tests (c2 ), single maker analysis (SMA), interval mapping (IM) were combined in the QTL analysis procedure. All approaches used for QTL detection obtained similar results. QTLs were identified for submergence tolerance with the emphasis on 26 QTLs related with 6 traits. Seven QTLs related to submergence at flowering focus on chromosome 8, 9 and 12. The proportion of phenotypic variation explained by each QTL ranged from 18.8 to 25.8% on chromosome 8, 14.8%, 24.2% to 32.4% on chromosome 9 and 19.0 to 25.9% on chromosome 12. Nine QTLs related with yield grain for Submergence at chromsome 1, 2, 3 and 11. Two QTLs related for 1000 grain weight on chromosome 2 and 11. Three QTLs for unfilled grain / panicle at chromosome 3, and 11. Two QTLs for plant height at chromosome 3. Three QTLs for tilling/plant on chromosome 3 and 11. This study has provided detailed information on the relative importance of marker-assisted selection of submergence tolerance in rice.