Mining Of Major Loci Of Maize Brittle Genes And Development Of Linkage Molecular Markers

The broken stalk of maize(Zea mays L.)can seriously damage the growth and development of plants,especially the break of tassel stalk before pollination,leading to the reduction of crop yield seriously.Stalk strength of mazie is closely related to its lodging resistance.The rind penetration resistance is an effective and reliable method for evaluating the strength of corn stalk.In this study,IBM syn10 DH population,which was founded by corn B73 and Mo17,and polymorphic GWAS natural associated population were used as materials.Rind penetration resistance and stalk diameter of tassel were measured during the flowering and powder scattering period in three environments.Major effect loci of brittleness traits were analyzed by linkage analysis,genome-wide association analysis and transcriptome sequencing.The development of SNP marker based on selected candidate genes is helpful for germplasm innovation and genetic improvement of maize.The main results are as follows:In IBM Syn10 DH population,the phenotypic values of rind penetration resistance(RPR)and tassel stalk diameter(TSD)showed continuous variation and accorded with normal distribution,which meet the requirement of QTL.Eight QTLs for rind penetration resistance and tassel stalk diameter were detected by linkage analysis under three environments.These QTLs were distributed on chromosomes 1,2,3 and 6.The percentage of phenotypic variance of a single QTL was 6.9% to 10.1%.The interval of qTSD1-1,qTSD1-2 and qTSD1-4 on chromosome 1 partially overlapped.The interval of qRPR2-1 and qRPR2-3 on chromosome 2 partially overlapped,whose peaks of two QTLs were 1.02 Mb apart.In the GWAS population,a total of 430 significant loci related to rind penetration resistance and tassel stalk diameter were detected in three environments.Three overlapping SNP candidate regions of tassel stalk diameter were detected in Taian Mazhuang and Taian south school,where 23 effective genes were identified.By analyzing the results of linkage analysis,association analysis and transcriptome sequencing,two candidate genes related to stalk brittleness were predicted.Zm00001d034844 gene encoded nucleotide diphosphate glycosyltransferase family protein,which was related to cell wall specific xylosyltransferase.Zm00001d034836 gene was related to the binding of GTPase domain.Through genome-wide association analysis,eight polymorphism loci in Zm00001d023753 gene were found that were significantly correlated with tassel stalk diameter.According to the polymorphic loci,SNP molecular markers closely related to stalk brittleness were designed,which could be used to screen the germplasm resources with good stalk strength of tassel.The above results will provide new genetic information for the study of the stalk strength of tassel in maize,and also lay a foundation for the linkage molecular marker assisted breeding of brittle genes.