Salt Tolerance Mapping Of RIL In Maize At Seedling Stage And Functional Verification Of Salt Tolerance Gene ZmCCR-like5 In Maize

Maize(Zea mays L.)originated in America.It is an important grain,feed and energy crops in China,and plays an important role in ensuring the food production security in China.Soil salinity is one of the main abiotic stresses affecting maize production.Mining and functional verification of maize salt tolerance genes will help to analyze the molecular mechanism of maize response to salt stress,and provide gene resources for breeding maize hybrid with improved salt tolerance.In this study,193 recombinant inbred lines(RILs)were derived from the cross of two maize inbred lines with significant differences in salt tolerance.We measured the traits of the survival days of plants under salt stress,the number of dead leaves at 15 days after salt stress,and seeding height difference caused by 10 days of salt stress in the RIL population at seedlings stage,and mapped QTL for salt tolerance.In addition,maize mutant and homozygous T3 generation transgenic rice lines were used to verify the the function of ZmCCR-like5,a salt tolerance candiated gene mapeed and cloned by us in our previous study.The main results are as follows:1.In this study,we developed 193 RILs using the cross of two maize inbred lines ZM185(salt tolerant)and ZM149(salt sensitive).A high-density linkage map with a total length of 2521.03 cM and an average distance between markers of 1.57 cM was constructed.QTL analysis revealed 17 salt tolerance related QTLs in the 193 RILs under two environments using using the following three traits as salt tolerance indexes:the survival days of seedlings after salt stress,the number of dead leaves after 15 days of salt stress,and the seeding height difference between control and salt treatment after 10 days of salt stress.These detected QTLs included four major QTLs,namely,qSD5-1、qDSH8-1、qRDL2-1 and qRDL10-1.The QTL qSD5-1 explained 20.09%-26.16%of the phenotypic variation,and its confidence choromosome interval contained ZmCCR-like5,the salt tolerance candidate gene mapped and cloned previously by our laboratory.2.Two T3 generation transgenic rice lines with overexpreesed expression of gene ZmCCR-like5 were identified.Under salt stress,compared with the control plants,the transgenice line plants showed significant higher values in seeding height,root length and relative water content,and lower values in malondialdehyde content and Na+content.In addition,we surveyed MaizeGDB and obtained maize ZmCCR-likes mutant zmccr-like5UFMu and its wild type(WT).Under salt stress,the WT survived longer and showed significantly higher seeding height than the mutant.These results indicate that overexpression of ZmCCR-like5 can enhance salt tolerance of plants.