QTL Mapping For Salt Tolerance Traits At Seedling Stage Of Wheat In A F_2:3 Family

Wheat plays an extremely important role in the global agricultural output,and is one of the most important food crops in the world.Recently,a mix of population growth,industrial pollution,improper irrigation,and the misuse of chemical fertilizers have made soil salinization an increasingly serious problem.Soil salinization has become one of the main problems in agricultural production.Wheat during its seedling stage is considered to have the weakest salt tolerance,Salt stress has large impacts on wheat seedling growth.Many correlated traits in wheat are quantitative traits that are controlled by multiple genes;and utilize these sites through molecular marker technology to improve wheat yield under saline conditions.This would allow for the cultivation of salt-tolerant wheat varieties that can be useful in solving the problem of soil salinity on grain yield in the future.In this study,the F₂ population?178 individuals?that is obtained from the cross between Zhongmai 175 and Xiaoyan 60 varieties,and the derived F₃population were used for QTL mapping.Salt stress was imposed in soil and hydroponic culturing.23 seedling traits were measured for the mapping.The genetic linkage map was constructed by SSR markers,and the QTL mapping was performed by the complete interval mapping method based on the results of phenotypic identification.Here we aim to lay a foundation for molecular marker-assisted selection and the cloning of the salt tolerance genes in wheat.147 QTLs were detected and distributed on 20 chromosomes?except for4B?based on the results of the localization analysis on salt tolerance related traits in wheat seedlings.Among these,8 QTLs contributed more than 10%of the explanined variation and 49 QTLs contributed more than 5%of the explanined variation.The sites related to the maximum root length are on chromosomes 2A and 4A,and the QTLs associated with seedling biomass were mainly located on the first and second homologous chromosome groups.The additive effect derived from the QTL of Xiaoyan 60 is mainly related to biomass and root length;while the additive effect derived from the QTL of Zhongmai 175 is mainly related to number of yellowing leaves and sodium ions.The F₃ population localized different traits of wheat seedlings to similar positions on the same chromosome by the same culture method.However,the localization of chromosome was distinguishing under different culture.Analysis of the repeatedly detected QTLs revealed that under salt stress,the QTLs associated with salt tolerance at the seedling stage are co-localized to 9major multi-effect sites.The results are also shown following salt stress.The F₂ population was used to locate the number of bad leaf number and salt injury index grown in soil.The F₃ population was used to locate the biomass?shoot fresh weight,shoot dry weight,root fresh weight,root dry weight and total dry weight?,tiller number,seedling height,root length,and other related traits under hydroponic conditions.And soil culture conditions Mutual verification through the QTL mapping of related traits that appeared in both F₂ and F₃ populations showed that the same related traits appeared between the two different growth methods?hydroponic conditions and soil culture conditions?.QTLs related to the number of yellowing leaves were detected in the78-79 cM interval on chromosome 6A using the F₃ population under both soil and hydroponic culturing conditions.The results showed that the same traits were located close together on the same chromosome,confirming the localization of genes related to salt-tolerant traits in wheat seedlings.