Genome-wide Linkage And Association Analysis Of Husk Number And Co-location Gene Mining In Maize

The planting area and yield of maize ranked first in China,but the level of mechanical harvest was relatively backward in some areas,which presented a serious imbalance between the planting area and yield and the level of mechanical husk.The main reason affecting mechanized harvest is that corn varieties widely used in China generally have the disadvantage of high-water content in the grain during harvest.Husks are wrapped in the outer ear,and the number of husks directly affects the water content of corn grains at harvest time.However,there are no reports on the mapping and cloning of key genes controlling husk number in maize.In this study,two DH populations and one related population were used as materials,respectively.Linkage and association analysis were conducted to integrate candidate genes for co-location regulation of husk number,which laid a foundation for subsequent breeding of varieties with rapid dehydration and easy harvesting.The main results are as follows:(1)Genetic basis of husk number in DH populationPhenotypic investigation of the two DH populations in two sites in one year showed that the bract number was significantly separated in the two DH populations,and the bract number was significantly different.The results showed that the phenotypic data of bract number were normally distributed,which could be used for further statistical analysis.Its generalized heritability was lower than medium level and higher than medium level respectively.Two major effect QTL and one micro effect QTL were identified.(2)Genetic basis of husk number in associated populationsThe inbred lines in the associated population were planted in three environments.After phenotypic investigation and data processing,the results showed that the phenotypic data of husk number in the three environments were normal distribution.The generalized heredity showed moderate to upper level and obvious subgroup effect.Husk number was widely correlated with agronomic traits,especially with panicle traits,suggesting that bract number may influence yield by influencing panicle traits.GWAS analysis revealed that 21 SNPs were significantly correlated with husk number.(3)Effect of husk number on grain water contentThere was a significant correlation between husk number and grain water content in DH and related populations.The husk number caused significant difference in grain water content.The husk number of DH1 population was less than that of DH2 population,and the grain water content of DH1 population was lower than that of DH2 population.The results showed that the inbred lines with more husk number had higher grain water content than the inbred lines with more husk number.(4)Husk number linkage and association analysis candidate gene co-locationIntegration analysis of bract number candidate genes revealed that two GWAS candidate genes co-located with the target QTL.Candidate genes Zm00001d017609 and Zm00001d028983.Tissue specific expression analysis of the two candidate genes showed that the candidate genes were expressed in husk number.