Study On The Genetic Diversity And Association Analysis Of Yield Traits With SSR Markers In Maize Inbred Lines

Maize is one of the most important cereal crops in the world, widely used in foodstuffs and industry. Meanwhile, it is extensively planted in our country but uneven distribution of regions. Investigation of the genetic diversity of maize will provide valuable information for corn breeding program. While high yield as the primary goal of maize breeding, genetic improvement of maize yield component traits has been one of the hottest topics in the field. In this study, a total of172maize inbred lines were used as experimental materials.115SSR markers in maize10chromosomes were adopted to explore the genetic diversity of maize. In addition, association analysis was carried out between the SSR markers and10yield traits based on population structure and linkage disequilibrium. The results were described in detail as follows:(1)115SSR primers were used to detect the polymorphism of materials. The experiment showed that644specific DNA bands were detected, and2-15polymorphic fragments were amplified by each primer with an average of5.6fragment. Polymorphism information content (PIC) value ranged from0.18to0.91, with an average of0.59. The average genetic diversity was0.64, varying from0.20to0.94. Primer umc1880had the highest PIC value and gene diversity value of0.91and0.92.(2) A total of172maize inbred lines were grouped into five subpopulations based on mixed model. The Nei’s genetic distance in PowerMarker3.0was used to calculate the distance of subpopulations. The results showed that the genetic distance between sub-group two and five was0.3981, for maximum. This suggested the local variety in our country had a relatively low genomic affinity tropical corn.(3) To some extent,6555combinations of two loci among115SSR primers were in linkage disequilibrium state, regardless of linear or non-linear combination. The proportion of unbalanced pairs of sites supported by statistical probability (P<0.01) was64.30%. However, the percent of combinations with D’>0.5was only1.08%. LD was very common for distances<400cM.(4) By association analysis based on population structure,21SSR markers were found significantly associated with10maize yield traits. Of all,7SSR markers associated with ear weight(EW), the interpretation rate of genetic variability of marker phi420701was37%;3loci were associated with ear length(EL)、rare ear length(REL)、ear diameter(ED) and cob diameter(CD);4SSR markers were associated with row kernel(RN), explained nearly43%by the variation. Loci associated with row kernel number(KNR) and grain weight(GW) were5, but only one markers was associated with grain%(G); the most locus associated with yield traits was SW, and the proportion of explaining was53%. The same loci associated with multiple yield traits of the situation was generally existed, and the markers phi420701associated with seven yield traits, relating contribution were higher than10%. Except chromosome5,42loci were distributed on the other chromosomes, and most of them were distributed on chromosome8and9.