Identification Of Salt Tolerance And Alkalinity Of Sunflower Seedlings And Genome-wide Association Study Of Related Characters

The soil salinization in northern China is serious,and the yield and quality of crops in these areas are reduced due to perennial saline-alkali stress.Sunflower,as the main crop for controlling saline-alkali land,has strong tolerance to saline-alkali,but there are significant differences among different varieties.It is of great significance to identify and mine new germplasm and important candidate genes of saline-alkali-tolerant sunflower for cultivating new varieties of saline-alkali-tolerant sunflower.In this experiment,163 oil sunflower inbred lines were planted in saline-alkali experimental field and conventional experimental field respectively,and the phenotypic traits related to salt-alkali tolerance were determined at seedling stage,and the salt-alkali tolerance of the materials was evaluated by statistical methods such as salt-alkali tolerance coefficient and comprehensive evaluation D value.Combined with the whole genome SNP loci developed by the research group in the early stage,the genome-wide association study of salt-tolerance related traits was conducted,the salt-tolerance related loci were excavated,and the candidate genes related to sunflower salttolerance were screened out,and the functional annotations of important candidate genes were made,which provided reference for further research on the molecular mechanism and molecular breeding of sunflower salt-tolerance.The main results of this study are as follows:(1)The correlation between salinity tolerance coefficient of each index and D value shows that root length,root surface area,root volume and root-shoot ratio can be used as identification indexes of salinity tolerance of sunflower seedlings.(2)The comprehensive evaluation D value of salt-alkali tolerance was calculated by the coefficient of salt-alkali tolerance,the subordinate function value of salt-alkali tolerance and the index weight,and the tested materials were divided into five types of salt-alkali tolerance.Among them,there are 29 materials with strong salt and alkali tolerance,such as 92,141 and 7,which can provide basic materials for sunflower hybrid breeding in the later stage.(3)When the threshold was-lg(p)>5.91,a total of 26 SNP loci were detected at the chromosome level,including 19 extremely significant SNP loci,and the significant SNP locus controlling both aboveground dry weight and underground fresh weight on chromosome 3 was detected,with the position of 10845841.(4)By comparing the 26 significant association marker sequences obtained from the association analysis,93 candidate genes related to traits were obtained,and 10 candidate genes possibly related to salt and alkali tolerance were screened out through gene annotation,and it was found that LOC110928588 could control both underground fresh weight and aboveground dry weight.