Identification of QTL for salinity tolerance at reproductive stage in rice (Oryza sativa L.)
2010
Calapit-Palao, C.D.O., Philippines Univ. Los Baños, College, Laguna (Philippines)
In order to identify QTLs for reproductive stage salinity tolerance, 201 plants from the F2 mapping population derived from the cross between IR64 (improved, salt-sensitive variety) and IR4630-22-2-5-1-3 (improved, salt-tolerant variety) were grown to maturity in the screenhouse after salt stress (10 dS/m electrical conductivity) was imposed during boot leaf emergence. Morpho-physiological parameters were measured and tested for correlation with the observed pollen fertility. Pollen fertility was significantly correlated with grain yield, tiller number, shoot dry weight, number of panicles, plant height, and single-grain weight. Meanwhile, grain yield was also significantly correlated with those parameters in addition to panicle length, root dry weight, % Na, and Na-K ratio. A 1281 cM linkage map was constructed using 104 SSR markers at an average interval size of 15.62 cM. Single marker analysis, simple interval mapping, and composite interval mapping approaches were utilized to detect QTLs. A total of 47 QTLs associated with reproductive stage salinity tolerance were tagged in 11 of the 12 chromosomes (chromosomes 1-8, 10-12) of rice. Twenty-six of the QTLs linked with %K, %Na, and plant height. These three traits co-segregated in chromosomes 2 and 4. Two QTLs each for pollen fertility and grain yield were also identified and co-localized with panicle length, shoot dry weight, root dry weight, %Na, and %K. The proportion of phenotypic variations explained by the QTLs ranged from 0.07 to 63.52%, with LOD values from 3.02 to 14.70. Fine mapping using a permanent mapping population derived from this cross is suggested in order to confirm and refine results.
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