Genome-Wide Association Study Of Theβ-Glucan And Trace Elements Content,and Identification Of Cellulose Synthase Gene Family In Barley(Hordeum Vulgare)

Barley is one of the most important staple crops,and its planting area and total output rank fourth in the world.Barley has important industrial value for food,feed and brewing.Moreover,barley is an ideal health food.In recent years,researchers have found that barley grains are rich in β-glucan and various trace elements such as iron,zinc,and selenium.Because of its high protein,fiber and vitamin content,as well as its low fat and sugar content,barley has gradually been regarded as healthy grain and has attracted more and more attention.Therefore,elaborating the genetic basis of barley β-glucan and trace elements,and excavating related genes that affect its content,are of great significance for molecular breeding.In this study,28 barley cultivars,8 barley landraces,29 wild barley,and 41 Tibetan barley were used for further research.The β-glucan,iron,zinc,and selenium contents of the 106 barley accessions in 2018 and 2019 were measured respectively.The traits were compared and analyzed,and the genome-wide association was used to screen SNPs loci and candidate genes significantly correlated with the contents of these four nutrients.And the gene families related to the synthesis of barley β-glucan were identified.The main results are as follows:(1)Analysis and comparison of β-glucan,iron,zinc,selenium content of barley grains harvested in two years showed that the coefficient of variation of each trait in 4 populations were below 10%,and the Shannon-Wiener diversity index was between 1.24 and 2.02.In different barley populations,there were significant differences within traits except for selenium content.And in four different barley populations,the content of these four nutrients was highest in wild barley.The nutrient content of wild barley is higher than other populations and its higher genetic variation,indicating that it has the potential to be used as genetic improvement of barley.(2)Based on the resequencing data,15,167,288 SNP loci were detected.Correlation analysis identified 72 loci that were significantly associated with β-glucan.And in the β-glucan content correlation analysis,two possible genes were found.The acquisition of this information provides resources for follow-up research.(3)By means of bioinformatics analysis,the latest reference genome and its annotation information(IBSC＿V2)of barley were used to systematically analyze the related gene families(Ces A and Csl)of barley synthesis of β-glucan at the genome-wide level.A total of 7 cellulose synthase genes(Ces A)and 24 cellulose synthase-like genes(Csl)were identified in the barley genome,providing the most comprehensive dataset of barley β-glucan biosynthesis genes.The phylogenetic relationship found that the Hv Csl family can be further divided into 6 subgroups,and each subgroup has more conservative gene structures and conserved protein domains.On this basis,the expression patterns of these genes were analyzed using RNA-seq data,and found multiple candidate genes related to tissue-specific expression and stress response.Finally,based on the interaction network of homologous genes,the regulatory networks of Hv Ces A and Hv Csl genes were constructed.This laid the foundation for further identification of the biological functions of gene families related to barley β-glucan synthesis.In summary,representative barley accessions which have different types and different sources were used in this study to systematically measure and evaluate the content of β-glucan and trace elements of iron,zinc,and selenium.Better accessions were identified and used for barley nutrition-enhanced breeding.On this basis,genome-wide association analysis was used to preliminarily locate the relevant sites and chromosome regions of barley β-glucan and trace elements content,and multiple QTLs were identified.Finally,the bioinformatics analysis was used to systematically identify and analyze the gene families related to barley β-glucan biosynthesis.The results of this study not only laid the foundation for revealing the molecular mechanism of barley nutritional quality,but also provided important tools for barley nutrition enhancement,genetic improvement and molecular breeding.