Mapping Of QTLs Conferring To Salt Tolerance In Wild Emmer, And Cloning And Expression Analysis Of Candidate Gene Responsible To Salt Tolerance

Salinization in soil is one of the most important aspect to prevent the production of wheat. The study involved in genetic mapping of QTLs and map-based cloning of candidate genes responsible to salt tolerance has fallen behind a lot, compare with the research work on crops such as rice（O.sativa）, maize（Z.mays） and barly（H. vulgare） due to the large genome of wheat. The study on genetic mapping, cloning and functional analysis of candidate genes related to salt tolerance is a very important work in theoretical research in order to illuminate the molecular mechanism of salt tolerance deeply and to cultivate new wheat breed exceed in salt tolerance. In this study, a set of common wheat-wild emmer chromosome arm substitution lines（CASLs） was introduced and their characters of salt tolerance in the period of germination and seeding were all examined. The result showed that CASLs1AS、6BL、2BS、4AL and 5AL were all significantly superior to their recipent parent CS, implying that these QTLs responsible to salt tolerance might exist on the chromosome arms 1AS, 6BL, 2BS, 4AL and 5AL separately.Two F₂ segregation populations 1AS×CS and 6BL×CS were formed using CASLs1 AS and 6BL as female parent and CS as male parent. Then, these QTLs responsible to salt tolerance in wild emmer were mapped preliminarily compare with the data of genotype and phenotype for each individual. The result showed that a major QTL conferring to salt tolerance was mapped on chromosome arm 6BL at the markers interval of Xbarc24-Xbarc354, explainning a total of 18.90% phenotypic variation. But to chromosome arm 1AS, no major QTL involved in salt tolerance was detected. Additionally, the ORF sequence of CBL1 gene was cloned in wild emmer using homology-based cloning technique. Through alignment of protein sequences with the homologous genes from cotton（Gossypium hirsutum）, rice（Oryza sativa） and maize（Zea mays）, very high homology was verified and several of conserved domains were also been confirmed, implying it was CBL1 gene. Finally, CBL1 gene was located on chromosome arm 1AS using SSCP test method. It was confirmed that CBL1 gene could respond to salt tolerance in CASL1 AS and CS, and to get a higher expression as the extension of salt induction at the Na Cl concentration of 1%. The increase rate of the expression of CBL1 gene in CASL1 AS was significantly higher than CS; After three days induction, all the seedlings showed the phenotype of salt damage and all their leaves were withered and yellow, and the expression of CBL1 gene was gradually decreased. CBL1 gene was located in cytoplasm using the subcellular ultramicro analysis, implying this gene could respond to salt tolerance through adjustment of the ratio of Na+/K+ in cell. This study will be a basic work for fine mapping and map-based clone for genes related to salt tolerance.