Genome-wide Association Study Of Agronomic Traits And Pericarp Thickness In Sweet Corn

Agronomic traits are very important for sweet corn.Plant height and ear height are associated with plant type breeding and lodging resistant breeding,respective ly.Leaf number above the ear affects the photosynthesis and yield of sweet corn.So mining these loci which control the variations of agronomic traits will provide theoretical support for sweet corn breeding.In addition,the pericarp thickness is an important component of sweet corn quality,and it is closely related to the taste of sweet corn.At present,pericarp thickness has become an important influence factor for the quality of sweet corn.Therefore,the research of variation for pericarp thickness and mining the favorable alleles controlling the pericarp thickness will contribute to sweet corn quality breeding.In this study,144 sweet corn inbred lines were selected as the experimental material,the genotype of these lines were detected through MaizeSNP50 genotyping chip and phenotypic data of these lines were measured such as corn plant height,ear height,stem diameter,leaf number above the ear,tassel length and pericarp thickness.The genome-wide association study was performed combining the ge notypes and phenotypic data to detect the associated SNP loci for agronomic traits and pericarp thickness.The results were as follows:1.The analysis of the population phenotypic data showed that plant height,ear height,stem diameter,leaf number above the ear and tassel length were consistent with normal distribution.The range of plant height was 105.11-249.86 cm with the mean of 166.16 cm,the range of ear height was 17.60-92.28 cm with the mean of 50.76 cm,the range of stem diameter was 9.87-20.43 mm with the mean of 15.19 mm,the range of leaf number above the ear was 2.60-9.90 with the mean of 4.93,the range of tassel length was 17.47-39.15 cm with the mean of 27.12 cm,pericarp thickness ranged from 43.75 to 179.79 μm with the mean of 98.05 μm.2.Correlation analysis showed that the correlation coefficients of leaf number above the ear and stem diameter,leaf number above the ear and plant height,plant height and tassel length,plant height and ear height,stem diameter and ear height were very significant positive correlation,and the correlation coefficient were 0.395,0.281,0.338,0.732,0.245;ear height were significant positive correlated with the leaf number above the ear,and the correlation coefficient was 0.180.3.Population structure analysis of 144 sweet corn inbred lines was carried out by structure software V2.3 and these lines were divided into six groups.The numbers of inbred lines from the first to sixth groups were 28,24,43,11,9 and 29,respectively.4.Two kinds of statistics methods including GLM(General Linear Model)and MLM(Mixed Linear Model)were selected to conduct genome-wide association study.In a total of six kinds of model,the model MLM + K inship + Q showed better than other models by judging deviation from the center of the situation,therefore,the model MLM + K inship + Q was selected to conduct the study.5.Association mapping analysis was conducted by combining genotypes with phenotypic data of plant height,ear height,stem diameter,leaf number above the ear,tassel length and pericarp thickness,and 59 SNPs were detected to be associated with leaf number above the ear.These SNPs located on the 1,2,3,4 and 10 chromosome,respectively.