Fine mapping of major effect QTL responsible for salinity tolerance (Saltol) in rice

This research was conducted to validate and fine map the region attributed to salinity tolerance on chromosome1 in rice (Saltol) at International Rice Research Institute (IRRI) during 2005 to 2007. A major effect QTL (Saltol) which is responsible for Na+ and K+ uptake and their ratio was identified using F8 recombinant inbred lines (RILs) of Pokkali/ IR29 cross on chromosome 1. This QTL explained around 64.3 to 80.2% of the phenotypic variation for the mentioned traits. Fine mapping was done using 10 SSR and EST-SSR markers and near isogenic lines (BC3F4), derived from IR29 × Pokkali that were produced for this trait. Random BC3F4 individuals were genotyped and phenotyped under two different electrical conductivities at seedling stage. QTL responsible for salinity tolerance at both ECs, were found in the same place in Saltol region, which explained 18 and 24% of the phenotypic variation for SES scores, respectively. According to the present results, possible location of Saltol was found in the interval around 1.2 cM on chromosome 1 that could physical map. It was around 350Kb. This QTL was mapped at the intervals of RM8094, RM3412 and CP6224. Therefore, molecular breeding for salinity tolerance in Iranian genotypes could be done using the mentioned markers.