Genetic Model Analysis And QTLs Validation For Storage Tolerance Related Traits In Waxy Maize

Safe storage of seed is very important for reducing crop production risk,maintaining seed market stability,ensuring seed security and food security.Improving the storage tolerance of maize seeds can reduce the cost of maize seeds,improve the use efficiency of seed,and effectively prevent the market risk of maize seeds.Therefore,it is important to study the genetic mechanism of seed storage tolerance for maize production.In this study,a cross combination N7×N32 was conducted by two waxy maize inbred lines N7（intolerant to storage）and N32（resistant to storage）.The genetic model analysis of two storage-tolerance related traits in waxy maize were carried out by six-generations combination analysis of P₁、P₂、F₁、B₁、B₂、and F₂,and the QTL mapping was performed by bulked segregant analysis.The results of the study are as follows:1.The best genetic model of unit seed mass electrical conductivity after storage was E-1（two pairs of additive-dominant-epistatic major gene+additive-dominant polygenic mixed genetic model）.The heritabilities of the major genes of the three separated generations B₁、B₂、and F₂were 96.84%,85.45%and 97.37%,respectively,and the heritabilities of the polygenes genes were 0.80%,0.00%and 0.40%,respectively.The additive effects of the major genes were all significantly larger than the dominant effects.The best genetic model of germination rate after storage was E-1（two pairs of additive-dominant-epistatic major genes+additive-dominant polygenic mixed genetic model）.The heritabilities of the major genes of B₁、B₂and F₂were 96.80%,63.99%and96.17%,respectively,and the heritabilities of polygenes was 0.00%,0.89%and 0.32%,respectively.The additive effects of the major genes were all significantly larger than the dominant effects.The best genetic model of two storage-tolerance related traits of waxy maize was E-1（two pairs of additive-dominant-epistatic major genes+additive-dominant polygenic mixed genetic model）,and the two traits were mainly inherited by major genes,and the genetic effects of each major gene were mainly additive.2.216 F₂individual individuals of N7×N32 were used as the genetic mapping population,and F₂individual plants were screened with two storage-tolerance indicators to form two extreme DNA pools by BSA method.Two primers umc1284 and bnlg2097,with polymorphisms between mixed DNA pools,located on chromosomes 4 and 6,respectively,were selected from 600 SSR primers uniformly distributed across 10 pairs of maize chromosomes.By redesigning 100 pairs of primers on these two chromosomes,a linkage map containing 39 SSR markers was constructed.A total of 7 QTLs were detected for 2storage-tolerance related traits by composite interval mapping.Two QTLs were located on chromosome 4,they were q EPW-chr4-1and q GP-chr4-1 with LOD values of 19.3 and 18.1,respectively,explaining 30.5%and 25.9%of the phenotypic variation,respectively.Five QTLs were located on chromosome 6,q EPW-chr6-1,q EPW-chr6-2,q GP-chr6-1,q GP-chr6-2 and q GP-chr6-3,with LOD values of 11.2,4.7,8.2,5.6,and 3.4,respectively,15%,5.39%,10.3%,8.2%and 4.6%phenotypic variation were explained.The LOD values of 7 QTLs for storage-related traits in waxy maize were relatively large,indicating that the storage-tolerance related traits of waxy maize have certain germplasm utilization value.There were 4 major QTLs that could explain more than 10%of the phenotypic variation,which can be used as breeding material in waxy corn breeding.