Association Analysis Of Resistance To Maize Gray Leaf Spot(GLS) And Prediction Of Candidate Genes

Gray leaf spot(GLS)is a serious leaf disease of maize in China and even in the world,which is great harmful and widely distributed,causing great losses to maize production.The most basic measure to prevent this disease is to breed and plant the disease-resistant varieties.In this study,241 inbred lines with wide sources are used to construct association population,and evaluate the resistance phenotype to GLS under natural condition in a severe disease area;The genetic diversity and population structure are analyzed by using SNP markers covering the whole genome;On this basis,the loci of resistance genes and the prediction of candidate genes are carried out by genome-wide association analysis,which could provide support for the breeding of GLS resistance.The main findings of this study are as follows:1.In this study,241 maize inbred lines are evaluated resistance to GLS in two-year field,the analysis of variance shows that Variance analysis results show that the differences between years,materials and years×materials are highly significant.There are 102 inbreds with medium resistance and above(resistance grade≤5)for both years of resistance evaluation,including 44 inbreds with disease resistance(R)and five inbreds with high resistance(HR),which can be used in the disease resistance breeding to GLS.2.Total 20586 high-quality SNP markers are obtained after strict quality control from SNP chip genotype data,which is used to analyze the genetic diversity of the association population.The results show that the genetic diversity of the Chinese/American maize in this study is higher than that of CIMMYT/Thailand maize,the genetic diversity of the Chinese maize is higher than the American maize,and the genetic diversity of the yellow grain maize is higher than the white grain maize.3.Through the analysis of group structure,241 inbred lines were successfully divided into five groups,which are the tropical/subtropical group(TST),temperate SS group,temperate NSS group,temperate Tangsipingtou group and mixed group.The results are consistent with the inbreds pedigree.4.The results of LD show that 57.14%of the paired SNPs have significant LD at the 0.01 level,which 10.32%of the paired SNPs have R~2 values greater than 0.1;The proportion of paired SNP in LD of tropical/subtropical maize is significantly lower than that of temperate maize as well as total maize in the study.5.Using the 20586 high-quality SNP markers and two-year phenotypic data of GLS,total 44 SNP loci associated with disease resistance to GLS are obtained by genome-wide association analysis at significance level P≤0.001(-1gP≥3),among which 34 are located on genes,corresponding to 31 genes distributed on chromosomes other than chromosome 10;Except for four genes,the remaining 27genes are located in the QTL interval mapped by previous studies.6.The 27 genes located in the QTL interval mapped by previous studies are compared in bioinformatics database,eight genes related to disease resistance are obtained,providing a basis for further gene function validation.