Identification Of Genetic Loci For Yield Related Traits Using Chromosome Segment Substitution Lines And Association Population In Sweet Corn

Yield is an important indicator of breeding,and varieties with high-yield,stable-yielding and high-quality are the primary issue in the development of the sweet corn.This study focused on the main goals of sweet corn breeding.A few yield-related traits were examined using the chromosome segment substitution population in our laboratory and associated population.And then the genotpyes of these two populations were employed by simplified genome sequencing and gene chips technologies.The combination of linkage analysis and association mapping analysis were performed to excavate these genes controlling the yield in sweet corn.These results will provide the theoretical foundation for increasing yield in sweet corn.The results of this study are as follows:1.The phenotypes of seven yield traits were identified using 130 sweet corn chromosome segment substitution lines.The results showed that the average weight of fresh panicle was 226.79 g,which ranged from 115.55 to 379.71 g;the average net weight was 145.55 g,ranged from 65.63 to 242.49 g;the average length was 17.25 cm,ranged from 10.50 to 24.00 cm;the average diameter was 42.86 mm,and the range was from 33.48 to 52.32 mm;the average ear row number was 12,ranged from 8 to 18.The average row kernel number was 28 with a range of 14-41.The average 100-grain weight was 32.06 g,ranged from 19.84 to 44.48.All the measured data were in accordance with the normal distribution and showed the quantitative genetic characteristics.Correlation analysis showed that fresh ear weight was positive correlation with net ear weight,ear length,ear diameter,ear row number,grain number per row,and 100-grain weight.The correlation coefficients were 0.89,0.47,0.67,0.35,0.48 and 0.41,respectively.The net ear weight were significantly and positively correlated with ear length,ear diameter,ear row number,grain number per row,100-grain weight.The correlation coefficients were 0.52,0.73,0.36,0.56 and 0.41.The ear length was significantly positive correlated with grain number per row.The ear diameter was significantly positive correlated with the ear row number,grain number per row,and 100-grain weight,and the correlation coefficients were 0.60,0.16 and 0.44.2.The phenotypes of seven yield traits were identified using a panel of association mapping population with 133 sweet corn inbred lines.The results showed that the average weight of fresh panicle was 186.31 g,which ranged from 61.34 to 403.21 g;the average net weight was 103.49 g,ranged from 21.27 to 267.23 g;the average length was 16.01 cm,ranged from 7.50 to 27.61 cm;the average ear diameter was 39.18 mm,and the range was from 27.00 to 52.46 mm;the average ear row number was 12,ranged from 8 to 22.The average row kernel number was 21 with a range of 6-41.The average 100-grain weight was 26.31 g,ranged from 13.28 to 45.12.All the measured data were in accordance with the normal distribution and showed the quantitative genetic characteristics.Correlation analysis showed that fresh ear weight was positive correlation with net ear weight,ear diameter,ear row number,grain number per row,and 100-grain weight.The correlation coefficients were 0.87,0.75,0.26,0.37 and 0.39,respectively.The net ear weight were significantly and positively correlated with ear diameter,ear row number,grain number per row,100-grain weight.The correlation coefficients were 0.84,0.36,0.55 and 0.44.The ear length was significantly positive correlated with grain number per row with the correlation coefficient of 0.15.The ear diameter was significantly positive correlated with the ear row number,grain number per row,and 100-grain weight,and the correlation coefficients were 0.42,0.22 and 0.46.The ear row number was significantly negative correlated with 100-grain weight with the correlation coefficient of-0.21.3.QTL mapping was performed by composite interval mapping to dectect QTLs for seven yield traits using 130 sweet corn chromosome segment substitution lines.The LOD threshold was 2.0 for further screening.A total of seventy markers were detected related to yield traits QTLs in sweet corn.These markers were associated with fresh panicle weight,net weight,length,and diameter,respectively.The average contribution rate of each marker was 10.94%,and the mean value of LOD was 2.7.Seven QTLs were located on chromosomes 1,2,6,and 8.Among them,3 QTL were detected for fresh ear weight,net ear weight,and ear diameter,and they all located on chromosome 1.The contribution rates were 7.3%,7.4%,and 7.9%,respectively.For the ear length,4 QTLs were detected,which were located on the chromosomes 2,6,6,and 8 respectively,and the contribution rates were 12.5%.14.0%,13.5% and 13.9%,respectively.4.Genome-wide association analysis was applied to detect the SNPs associated with yield-related traits in association mapping population.General Linear Model(GLM)and Mixed Linear Model(MLM))were selected to analyze genome-wide association with yield traits,which were including fresh ear weight and net ear weight,ear diameter,ear row number,grain number per row,and 100-grain weight.4 SNPs wer associated with ear length were detected,which were located on chromosomes 1,3,and 8,respectively;9 SNPs were associated with 100-grain weight,which were located on chromosomes 1,5,and 7,respectively.