QTL mapping of IR64 mutants F2 population for salinity tolerance at seedling stage in rice
2012
Katimbang, M.L., International Rice Research Inst., Los Ba�os, Laguna (Philippines). Crop and Environmental Sciences Div. | Nokhoda, B., Agricultural Biotechnology Resources Inst. of Iran, Mahdasht Rd., 31535-1897 Karaj (Iran). Dept. of Molecular Physiology | Egdane, J. | Ismail, A.M., International Rice Research Inst., Los Ba�os, Laguna (Philippines). Crop and Environmental Sciences Div.
Salinity tolerance in rice is a quantitative trait. Rice is sensitive at seedling and reproductive stages; however, the tolerance at seedling stage is crucial for better crop establishment in the field. In the present study, the authors report the detection of QTLs for salinity tolerance at the seedling stage identified in an F2 population derived from the cross between an IR64 sensitive mutant (IR730-1) and FL 478, a highly tolerant RIL. Out of total 200 F2 segregating plants, 48 plants with extreme phenotype for salinity stress response, i.e. tolerant and sensitive, were used for selective genotyping based on visual seedling stage salt tolerance symptom. A linkage map was constructed with 69 SSR and 142 SNP markers evenly spread throughout the whole rice. QTL analysis using simple interval mapping and detected two major QTLs on chromosome 1 and 4 with phenotypic variances (R2) of 30% and 29%, respectively. QTL related to root Na+/*K+ ration on chromosome 1 was flanked by a SNP marker id1027099. Major locus for SES was bracketed by RM518 and a SNP marker id4001113 spread over about 7.0 mbp on chromosome 4. Identification of any tightly linked markers in this region will serve as a candidate gene for fine-mapping. QTLs identified in this study, after fine-mapping, could be used for marker assisted selection and to idetify the map positions of the mutations.
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