Identification and Fine Mapping of a Mutation Conferring Salt‐Sensitivity in Rice (Oryza sativa L.)

Abstract

ABSTRACTSingle‐gene mutants tolerant or sensitive to salt stress are ideal materials for identifying and cloning genes related to salt tolerance in rice (Oryza sativa L.). In the present study, a salt‐sensitive mutant was obtained from the ethyl methanesulfonate (EMS)‐induced Nipponbare bank. The mutant, designated rice salt sensitive 4 (rss4), showed a significant increase in salt sensitivity at the seedling stage and accumulated high levels of Na+ in shoots, particularly in the blades of old leaves, under conditions of NaCl stress. Genetic analysis indicated that the mutation was controlled by a single recessive gene. Quantitative trait locus (QTL) analysis for shoot Na+ content was performed using an F2 population derived from a cross between the rss4 mutant and the indica cultivar Zhaiyeqing 8 (ZYQ8). Three QTLs were identified and one located on the long arm of chromosome 6 was determined to be the candidate locus of the rss4 gene based on comparison and analysis, which explained 40.5% of the phenotypic variance in the shoot Na+ content of the F2 population. Further analysis of recombination events in 165 mutant individuals of an enlarged mapping population of rss4/ZYQ8 defined the rss4 locus to an interval of 230.5 kb bracketed by markers RM20566 and IM28706 on chromosome 6.