Association Mapping Of Agronomic Traits On Chromosome 2A Of Wheat

Most agronomic traits related to yield in wheat are quantitative traits. Mapping these traits not only to research the genetic law, also can contribute to marker assistant selection and give the baseline of gene clone.The materials of this study are 108 wheat varieties. Analysis of genetics diversity and population structure were conducted by using wheat lines in order to clarify population structure of these lines, and in addition, phenotypes related to yield traits were characterized for the set of materials. The linkage disequilibrium (LD) of chromosome 2A was calculated. At the end, association test between SSR marker polymorphisms with phenotype variation were performed in to identify loci that are responsible to phenotype variations with yield. The major results are as follows.1. Totally 108 wheat lines were assayed for genetic diversity at 48 Simple Sequence Repeat (SSR) loci and 40 EST-SSR loci. The results showed that total 826 alleles were identified; the average of alleles per locus was 5.7. Analysis of population structure assigned the 108 lines into 9 clusters. Most of wheat lines are of admixture kinship, and the result of population structure analysis was similar to cluster analysis.2. The baseline of LD decay is r~2=0.073 and LD extended 2.3cM in chromosome 2A. It is suitable to use genome scan association analysis approach. Two LD blocks were found, one is near the centromere and another is in the short arm of chromosome 2A.3. Marker-trait association analysis was calculated by mixed linear model in software TASSEL 2.1. 14 SSR loci were detected significant associated with agronomic traits, for example, gwm294 was significant associatied with grain number of spike and it can be repeated in three locations. Some SSR markers were found associated with multi-trait. These markers were most located near or in the QTLs region which were found in previous studies. The average of marker interval on chromosome 2A in our study is 3.75cM; it's higher than normal linkage analysis. It indicate that association mapping can be a viable alternative to QTL mapping based on crosses between inbred lines for detecting complex traits and achieves higher resolution than linkage mapping.