Comparison And Evolution Of Root Characters Of Different Barley Populations

Barley is the fifth largest food crop in the world.It has food,feed and industrial brewing value.Wild barley,as the direct ancestor of cultivated barley,has rich genetic diversity and has been an important germplasm resource for barley genetic improvement.The root system is closely related to the life activities of plant,but the characters of root system show significant differences under different growing environments.Therefore,it is important to study the agronomic characters of root system.In this study,106 barley germplasm from different populations were used to compare root traits,salt tolerance and drought resistance at seedling stage.The SNP loci and candidate genes of related traits were preliminarily identified and explored by genome-wide association analysis based on resequencing,which provided material basis and theoretical basis for further exploring excellent barley germplasm and genes.The main findings are as follows:1.Nine root traits of 106 germplasm materials in control group,drought stress group and salt stress group were measured,and root traits,drought resistance and salt tolerance were comprehensively compared.The results showed that the average values of root traits of cultivated barley varieties were higher in the control group as a whole.Under drought stress,the longest root length,root surface area,root volume and average total root length of different barley populations increased significantly.The mean values of longest root length,root surface area and root volume of different barley populations increased significantly under salt stress.The variation range of root traits in PEG treatment group was wider than that in Na Cl treatment group.It was concluded that drought stress was more effective than salt stress in inducing the differences of drought and salt tolerance in different populations of barley.The results of membership function analysis,variance significance analysis,principle component analysis,correlation analysis and cluster analysis,It was found that cultivated barley showed higher drought and salt tolerance in each analysis,while wild barley had higher genetic diversity of stress resistance,and was an important germplasm resource for genetic improvement of cultivated barley.2.Genotyping of these 106 germplasms was performed using whole-genome resequencing technology.After quality control and filtration,SNP typing data were obtained.The genome-wide association analysis of root system,drought resistance and salt tolerance was carried out with the phenotypic data of control group,drought resistance group and the ratio of salt tolerance to control group.Thirty-five SNPs associated with root traits were identified and distributed on 7 chromosomes.The 24 SNP loci were found on 6chromosomes except 1H.The 15 SNP loci were found on 6 chromosomes except 2H.3.In the 190 kb range of root related significant loci,31 root related candidate genes were screened.Among them,13 are related to root growth and development,5 are related to root growth and development.Three genes related to plant hormones,one gene related to sodium transport,one gene related to water and nutrient transport,one gene related to defense oxidative stress,and two genes related to causative agent recognition.4.A total of 29 root related candidate genes were screened in the 190 kb range of the significant loci related to drought resistance.Among them,21 genes were key genes related to root system,including 3 genes related to osmoregulation,1 gene related to antioxidant,Two genes related to plant hormones,two genes related to photosynthesis,two genes related to ubiquitin mediated proteolysis,four genes related to protein serine / threonine kinases,two genes related to causative agent recognition and five genes related to glycan recognition.5.Seven candidate genes related to root system were screened in the 190 kb range of the significant loci related to salt tolerance.Among them,5 genes were key genes related to root system,including 2 genes related to plant metabolism,1 gene related to inorganic ion concentration,1 gene related to plant hormones,and 1 gene related to ubiquitin mediated proteolysis.