Genome-wide Association Study Of Grain Traits In Barley(hulless Barley)

Barley is the fourth largest food crop after rice,wheat and corn.It has a long history of cultivation.Barley can be used as feedstuff,foodstuff,raw material of beer industry and medicine industry.It’s also one of the main rations in Tibet and Qinghai.Barley in China mainly depends on imports.In recent years,the contradiction between supply and demand of barley has become more and more serious.Grain characters are important measures of barley yield and quality characters.In this study,192 materials from all over the country were selected for phenotypic identification and comparison by characters like barley 1000 grain weight,grain length,grain width and length width ratio in the field;based on high-throughput sequencing technology,the whole genome of related population was resequenced,SNP genotype of related population was analyzed,the phenotypic and genotype data were combined.This study also carry out genome-wide association analysis of barley grain characters in different environments.And the main results are as follows:1.The difference of barley grain characters among different genotypes is significant,and the span is large.The high coefficient of variation of each character indicates that there are abundant phenotypic diversities in each character.However,there was no significant difference in 1000 grain weight,grain length,grain width and ratio of length to width among the materials from different sources by variance analysis,which indicated that these characters of barley were less affected by regional factors and mainly affected by genotype.2.Correlation between barley grain characters: the analysis of barley grain characters in different environments shows that there is a significant correlation between 1000 grain weight,grain length and grain width,and there is a positive correlation between grain length and length width ratio.Grain width and aspect ratio,1000 grain weight and aspect ratio showed significant negative correlation.Through PCA analysis,we found that barley materials from different sources could not be separated obviously,but through the analysis of different materials,we found that there was obvious separation between materials,and can be divided into three categories through cluster analysis.The results showed that these characters were less affected by the environment,and the correlation between grain width and 1000 grain weight was the highest according to the correlation analysis.The varieties with extreme characters can be used as the original materials for barley genetic breeding.3.In this study,we located four QTL loci that had been located for different years(QTL3,QTL4,QTL11,QTL21),20 locus related to 2 characters,All of them can be used as candidate sites for further study.Locus associated with genes involved in multiple biological processes(lipids metabolism,dextran,Transcription Factor,Hormone),it is suggested that the grain size and 1000 grain weight of barley are controlled by many genes,which are related to multiple characters.The genes related to lipid metabolism,transcription factors and hormones have a greater impact on grain size.In this study,we used the representative barley(hulless barley)germplasm to compare and analyze the grain characters,it revealed the different correlation of different environment and different barley(hulless barley)varieties.Compared with the existing reports and barley gene annotation information,some potential functional regions and candidate genes were obtained,which provided a reference for barley gene mining.