Studies on identification of putative quantitative trait loci for alkaline tolerance in rice (Oryza sativa L.).

摘要

In the present investigation an attempts has been made to identify the putative genomic regions/Quantitative trait loci governing alkaline tolerance in CSR 27. A Substantial variation was observed for salt injury scores and Na uptake. Salt injury scores of the F₃ population ranged from 4.00 to 9.00 with a mean value of 5.99. Na uptake values ranged from 1.25 to 2.50 mmol/g dry weights with a mean of 1.29 mmol/g dry weight. The frequency distribution of mean phenotypic values of the two traits clearly indicated that it is not major genes but poly genes that are controlling the trait expression showing continuous segregation of genes. A total of 208 SSR primers were used for polymorphism survey of parental cultivars. Of the 208 microsatellites tested, 120 SSRs amplified well scorable fragments between parents. However on repetition of polymorphic markers between parents and selective genotyping of polymorphic SSRs in tolerant and sensitive F₂ genotypes resulted in further narrowing down of SSRs to 45 which yielded clear cut SSR loci. Percentage polymorphism was found to be 21.6 between parents. A set of 190 DNA samples of F₂ genotypes were screened with 45 polymorphic SSRs. The QTLS and their effects for salt injury scores and Na uptake were obtained using QTL cartographer version 2.5 employing composite interval mapping (CIM) methods.