Genome Wide Association Analysis And Linkage Analysis Of Resistance Of Gray Leaf Spot In Maize

The Gray Leaf Spot,caused by Gercospora zeae-maydis、Cerospora zeina become one destructive disease for corn production in Southwest China.Breeding resistant hybrids are effective methods to control the Gray Leaf Spot basing on exploration and identification resistant resources and resistant gene.In rescent years,Application of whole genomics to identify resistant gene are important approach in maize disease resistance molecular breeding.In this study,345 maize inbreds were apply for research materials from different genetic backgrounds.The disease resistance of 345 maize inbred lines was evaluated under the nature environment;Using SNP maker covering whole genomics,The population genetic diversity and structure was analysed;With SNP marker of whole genomics,the SNPs correlated with GLS were identified by association analysis depending on whole genome screening;Depended on linkage mapping from IBM Syn10 population,QTL correlated with GLS were located by linkage analysis.The main research results were summarized as follows:1.A total 43070 high quality SNPs marker that obtained from 56110 SNP markers were use to evaluate genetic diversity.A maximum of SNPs were located in chromosome 1,there were 6724 SNPs.A minimum of SNPs were located in chromosome 10,there were 3075 SNPs;A total 86140 allele were identified,the average genetic diversity was 0.3607 and the variation range from 0.0953~0.500,the average PIC was 0.2884 and variation range from 0.0507~0.375;Population structure analysis indicated that the 345 maize inbred lines could be subdivided 6 subgroups,4 subgroups were accord with the 4 main germplasm resources which were BSSS、Reid、PA、PB respectively.The other two groups were Tropical/subtropical subgroup and North subgroup.2.The GLS resistance of 306 maize inbred lines were surveyed in 4 environments from 345 inbred lines,The results showed that susceptible(s)and high susceptible(HS)account for 71.6%,high resistance(HR)and resistance(R)only account for 14%;To investigate resistance variation of 306 maize inbred lines in 4 environments,there were 34 inbred lines with consistency in GLS resistance,114 inbred lines differed from 1 levels,125 inbred lines differed from 2 levels,30 inbred lines differed from 3 levels,3 inbred lines differed from 4 levels;To analyse 306 maize inbred lines from different subgroups,Tropical/subtropical and PB germplasm with high resistance(HR)and resistance(R)for GLS were the excellent breeding materials on maize breeding.3.The association analysis results indicated that 142 SNPs were correlated with maize GLS on-logP≥3 in 4 environments(exclude repeated marker).1 SNP marker were found in 3 environments.14 SNP markers were found in 2 environments.With 15 SNPs markers obtained in 2 or 3 environments,10 SNPs which account for 66.6% were located in chromosome 1,7 SNPs were located in bin1.05 and bin1.06.The results confirm that bin1.05-bin1.06 is an important area for resistant QTL detected on GLS.4.The GLS resistance of 260 maize inbred lines from IBM Syn10 population and parents were surveyed in 6 environments.Depended on bin map genetic linkage map that include 1.15 million SNPs,2916 SSR/RFLP and 6618 bin marker loci.This study used composite interval mapping(CIM)method to analyse resistant QTL locis.The result showed that 19 resistant QTL locis which distributed on chromosome 1,2,3,4,5,6,8,9 were obtained.The QTL qmGLS2-1,q13lGLS2-1,q14lGLS2-1 are located in bin2.04,The QTL q13lGLS3-1,q14lGLS3-1 are located in bin3.07,The QTL q13dGLS8-1,q14dGLS8-1 are located in bin8.03 and QTL q14lGLS2-1 could explained 10.24% of the phenotypic variation.