| Sweet corn is favored by more and more people because of its highly nutritional value and delicious taste.However,it is difficult to produce sweet corn hybrid seeds because of its low starch content,which leads to high cost and poor storage resistance.Therefore,the aging resistance of sweet corn seeds is an important trait.The study on the difference between natural aging and artificial aging,QTL mapping,cloning and functional analysis of these genes can help to reveal the regulation mechanism of seed vigor of sweet corn and provide the basis for breeding new varieties with high-vigor sweet corn.In this study,58 sweet corn inbred lines were used as experimental materials to study the difference between artificial aging and natural aging.Using gene chip technology and artificial aging method,an association population including 122 sweet corn lines was constructed and measured these traits for seed vigor,and these candidate genes on seed vigor were predicted based on bioinformatics analysis.The main results of this study are as follows:1.Artificial aging and natural aging germination tests were carried out using 58 sweet corn inbred lines.Variance analysis showed that there were significant differences in germination potential,germination rate,germination index,vigor index and seedling fresh weight.These indexes of seed vigor were significantly different between natural aging and artificial aging.Correlation analysis found that there were significant correlated between these seed vigor indexes for artificial aging and these seed vigor indexes for natural aging after 2,4 and 6 months at 0.01 level,the corresponding correlation coefficients of germination index were 0.490,0.467 and 0.435,respectively.2.The analysis of difference between artificial aging and natural aging showed that the germination potential and germination rate of the 58 sweet corn inbred lines were consistent and their Euclidean distances were less than 5.The consistencies of germination index andfresh weight of seedlings were poor,and their Euclidean distances were ranged from 10 to20.The difference in seed vigor index was significant,and the Euclidean distance reached more than 150.The effects of artificial aging and natural aging on seed vigor of sweet corn were consistent in the germination potential and germination rate,and different in seed vigor index.3.Standard germination test were carried out using the associational population seeds and seeds after artificial aging,respectively.Compared with standard germination using untreated seeds,these seed vigor indexes including germination potential,germination rate,germination index,vigor index and seedling fresh weight using seeds after 72 h of aging decreased significantly at an extent,and the vigor index was the fastest declining indicator,with a decline rate of 48.27%.The correlation analysis showed there were significant correlated between these seed vigor indexes of artificial aging and untreated,the correlation coefficient of germination index reached 0.536.The analysis of variance showed that the differences of materials on these seed vigor indexes were significant at 0.01 level,and the difference between artificial aging and untreated seeds were significant,too.4.Genome-wide association analysis on seed vigor traits was carried out and 13 significant associated SNPs were detected in this study,which were associated with germination index,germination rate and fresh seedling weight,respectively.Among of them,9 SNPs were associated with seed vigor indexes by standard germination experiment,which were located on chromosomes 2,3,4,7,9 and 10,respectively,and they could explain12.580～19.711% of the total phonotypic variance.4 SNPs were associated with seed vigor indexes by the seeds after artificial aging,which were located on chromosomes 1,3,4 and 9,respectively,and they could explain 13.258～18.974% of the total phonotypic variance.3main associated SNPs were detected and the phenotypic variances explained by them were greater than 18.000%.They were located on chromosomes 2,3 and 10,and their related SNP markers were pze-102019300,pze-103069554 and pze-110014718,respectively.5.The gene annotation of the interval of the upper and lower 50 kb of these associated sites was carried out based on the maize genome database and bioinformatics.A total of 31 candidate genes were screened out.According to the gene annotation results,five genesrelated to seed activity were selected as the candidate genes,including Zm00001d044816,Zm00001d052192,Zm00001d044780,Zm00001d002288 and Zm00001d044777.Zm00001d044816(casp-like protein)has interaction effect with peroxidase.Zm00001d052192(Cupredoxin superfamily protein)involved in the abscisic acid signal transmission and Zm00001d044780(DNA polymerase lambda)is closely related plants DNA repair,Zm00001d002288(b HLH transcription factor 148)regulates drought-resistant signal transduction,Zm00001d044777(DUF679 domain membrane protein 7)plays an important role in tissue aging process.They might be the candidate genes on regulating seed vigor in sweet corn. |
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