Genetic Mapping Of Wheat Brittle Culm Genes And Transcriptome Analysis

Crop culm strength is an important agronomic trait,which is closely related to agricultural production.However,we know very little as yet about the physicochemical properties of wheat stem and the regulation mechanism of cell wall synthesis.The wheat EMS mutants-brittle culm mutants of Emai 596 and Zhengmai 9023 was established and selected in our previous work.Totally,nine brittle culm mutants were obtained.On the basis of the phenotype differences between brittle culm mutant and the wild type in agronomic traits,cell wall components and physicochemical properties of straw.We have also done some research including the population construction,transcriptome analysis,BSA(BSR-seq),SSR-BSA to screen the associated markers and preliminary mapping.Our work will be helpful to the final map-based cloning of the gene and to reveal the metabolic pathways regulating cell wall physical and chemical properties.This dissertation mainly consists of three parts:(1)the comparison of the agronomic traits and the cell wall related phenotypic traits between the brittle culm and the wild type.(2)SSR-BSA screening of brittle stem genes and primacy mapping of BSA(BSR-seq)in the transcriptional group.(3)analysis and comparison of brittle culm mutant and wild type transcriptional group.1.Mutations in the brittle stem genes do not necessarily lead to a direct change in certain agronomic character,indicating that the changes in wheat cell wall and physical characteristics of the stem does not necessarily affect agronomic traits.Cell wall cellulose content decreased in all brittle culms,and the content of hemicellulose and lignin changed.In EC1?ZC6 and ZC7,the breaking force did not change significantly,and the stems showed brittleness.The traits of plant type have changed in varying degrees.In terms of yield,ZC2 declined for two consecutive years.ZC6 and EC1 increase for two consecutive years.2.According to the primacy screening of SSR-BSA among the combinations,it can be seen that the associated markers are most frequently detected on chromosomes 5A and 2A.It is speculated that there are functional genes controlling cell wall synthesis on chromosomes 5A and 2A.An associated marker Xgwm148 on the 3B chromosome was found in the F2: 3 population of Zhengmai brittle culm 4 and Yangmai 158.In Zhengmai brittle culm 2×Yang Mai 158 and F2: 3,it was found that the Gwm186 exchange rate of 5A chromosome was the lowest,26.8%,and the two adjacent markers Xgwm129 and XGPW2273 exchange rates were all greater than 40%.In the F2: 3 small population transcriptome BSR analysis of Zhengmai brittle culm 5 ×Yang Mai 158,it was found that there was a SNP associated with the target traits on 5B chromosome.The correlation between SNP and target traits was found to be 9.2%.3.After the transcriptional,the total data of each parent was above 16 G,and the number of different genes was more than 18000 after the comparison of the wild type.The GO number annotation and enrichment analysis found that cellulose synthesis related items such as the cellular glucan metabolic process,microtubule-based movement,cellulose biosynthetic process and sucrose biosynthetic process were significantly enriched in most brittle culms.In the KEGG pathway analysis,there were significant changes in the cellulose synthesisrelated pathways such as Biosynthesis of secondary metabolites,Pentose phosphate pathway,and Starch and sucrose metabolism.Finally,we discussed the agronomic traits,the genetic location of brittle culm genes,the transcrtiptome comparison results,and prospected the future studies of this project.