Physiological Of Artificially Aged Seeds And Gene Mapping Of Vigor In Sweet Corn

Sweet corn is more and more popular because of its rich nutrition and unique flavor.However,the low vigor of sweet corn seeds has always been a problem.Sweet corn seed has low vigor,low seed production,high price and poor storage capacity,which greatly hindered the promotion of sweet corn.Therefore,the study of biochemical and physiological aging of sweet corn seeds,and the mapping,cloning and functional studies of genes related to the vigor,are not only reveal the regulation mechanism of seed vigor,but also provide theoretical basis and support for the cultivation of high-vigor varieties of sweet corn.This study is mainly divided into two parts.In part,‘Nongtian88' and ‘Nongtian99' were selected as experimental materials and their seeds were treated using the method of artificial aging.The germination potential,germination rate,germination index and vigor index were measured using the method of germination in sand bed.In the other part,Quantitative trait locus(QTL)for seed vigor of artificially aged BC4F3 population was identified using Specific-Locus Amplified Fragment Sequencing,and predict the major genes regulating seed vigor.The main research results of this study are as follows:1.With the increase of aging time,seed germination potentials,germination rates,germination indexes and vigor indexes of ‘Nongtian88' and ‘Nongtian99' decreased gradually,indicating that seed aging reduced seed vigor.Comparing the decline in seed vigor under aging conditions of the two varieties,it was found that the anti-aging ability of 'Nongtian 88' seeds was stronger than that of ‘Nongtian 99'.2.With the increase of aging time,DHA activities and POD activities of ‘Nongtian88' and ‘Nongtian99' decreased gradually,while the relative electrical conductivities and MDA contents increased gradually.The correlation analysis showed that the RECs and MDA contents of two sweet corn seeds were significantly or very significantly negatively correlated with vigor indexes,while DHA and POD activities were significantly or very significantly positively correlated with seed vigor indexes.It was shown that DHA activity,POD activity,relative electrical conductivity and MDA content can be used as indexes for detecting seed vigor.3.Compared to CK,the seed genetic diversities decreased after artificial aging treatment,the allele numbers,effective allele numbers,gene diversities of ‘Nongtian88' and ‘Nongtian99' seeds decreased by 29.35% and 23.58%,25.00% and 20.00%,96.99% and 83.35% respectively on the 6th day of aging treatment.4.The BC4F3 population seeds were measured by the aging germination test and the germination test,respectively.Compared with the unaged seeds,the average value of germination potential,germination rate,germination index,vigor index,and fresh weight of the seedlings of aged seed all decreased.The seed vigor-related traits data all subject to normal distribution.5.Correlation analysis showed that the correlations between aged seeds and unaged of seeds seed vigor related traits reached extremely significant levels,namely,germination potential,germination rate,germination index,vigor index,seedling fresh weight,aging germination potential,aging germination rate,aging germination index,aging vigor index,aging seedling fresh weight were very significantly positively correlated with each other.Variance analysis found that among the materials,the germination potential,germination rate,germination index,vigor index,and seedling fresh weight all reached extremely significant differences;between treatments,the germination potential,germination rate,germination index,vitality index,and seedling fresh weight were all Extremely significant differences have been achieved.6.The linkage analysis between the genotype data and the phenotype data of sweet corn seed vigor,42 QTLs were detected.Based on the germination test,18 QTLs were detected,distributed on chromosomes 7 and 10.The contribution rate was between 0.052% and 13.138%,and the additive effect is mostly negative.Based on the aging germination test,24 QTLs were detected on the chromosomes 1,3,4,5,6,7,and 10.The contribution rate was between 0.052% and 13.138%,and the additive effect is mostly negative.Based on the contribution rate greater than 10,two major effect QTLs,q AGR10-2 and q AGR10-3,were mapped on chromosome 10.7.There were 21 candidate genes in the mapping region of Marker393-Marker398 according to Maize Genetics and Genomics Database.Among them,four genes,Zm0e0001d024488,Zm00001d024497,Zm00001d024498,and Zm00001d024500,may regulate seed vigor.