| Lodging has always been an important factor affecting the high and stable yield of corn,and it is also the main factor restricting mechanized harvest.Stalk strength and fiber quality are closely related to plant lodging resistance,which are increasingly valued by breeders.Studying the genetic basis of the stalk strength and fiber quality traits and its combining ability of germplasm resources can provide the foundation for lodging resistance and density breeding.In this study,we measured phyenotype of the lodging-resistance traits at natural population,F1 population which 100 inbred lines tested cross by four test lines,recombination inbred lines constructed by X178 and NX531 under multiple circumstances.The combining ability of the lodging-resistance traits were identified by 400 hybrids.QTL analysis was performed combining with sequencing-based high-throughput SNP molecular markers against lodging resistance traits and its combining ability.The results were as follows:1.In this experiment,we identified the lodging resistance traits of the natural population,the recombinant inbred population and the F1 population.The coefficient of variation of the lodging resistance traits of the three populations were higher in all environments,indicating that the lodging resistance traits are rich in phenotypic diversity.2.Genome-wide association analysis was performed by using 83057 SNP markers which obtained by GBS genotype analysis and BLUP values of the lodging resistance traits.A total of 318 association loci were detected by using the BLUP values of nine traits.The stalk rind strength,stalk bending strength,length and diameter of the third internode,length and diameter of the fourth internode,cellulose content,hemicellulose content,and lignin Content were detected association locis 163,14,29,16,20,16,39,9,and 12,respectively,and the phenotypic contribution rate of individual loci ranged from 7.05% to 19.14%.There are 15 segments where multiple traits are co-localized.3.Investigating the general combining ability and heterosis of lodging resistance of F1 population.The genotype variance of the general combining ability of all the traits exceeded its specific combining ability,indicating that the additive effect of the parents played a major role in the traits of the hybrid generation.The association analysis of the general combining ability of lodging resistance traits revealed that 49 associated sites of GCA were detected.4.BLUP predictions of lodging resistance traits were performed on phenotypic traits in all environments of the RIL population,and linkage analysis was performed by using BLUP values of lodging resistance traits.21 traits were co-localized for all traits,including stalk rind strength,bending strength,third internode diameter,fourth internode length,fourth internode diameter,cellulose content,hemicellulose content,and lignin content was mapped to 5,2,2,2,2,3,and 3 QTLs,and the contribution rate of a single QTL phenotype ranged from 0.94% to 19.86%.Hemicellulose content?60.799-71.405 cM?and lignin content?46.060-71.405 cM?were mapped to common QTLs on almost the same interval on Chr2.5.Compared the positioning results of the three populations.There are 6co-localization segments of natural populations and F1 populations,9 co-localization segments of natural populations and RIL populations,and 5 co-localization segments of RIL populations and F1 populations.Among of these segments,the colocalized segments of the three populations were Chr5212.877-215.185 Mb,Chr6127.258-130.884 Mb,and Chr9131.584-138.705 Mb.In this study,the linkage analysis and association analysis were used to analyze the lodging-resistance traits of three populations?natural population,RIL population,and F1 population?,and the QTLs for stability of resistance to lodging resistance and its combining ability were located.It provides a theoretical basis for genetic improvement and molecular marker breeding of maize. |
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