| Elite wheat germplasm resources are important to wheat breeding. In recent years, the frequency of extreme weather events increase as the global temperature rises; this has produced huge adverse effect on boosting wheat yield, such as drought, cold damage, late spring coldness, high temperature appearing in the growth stage of wheat. The decline of genetic diversity of wheat from Huang-huai winter wheat region would reduce the ability to resist adverse climatic change. Therefore, it is essential to study the genetic diversity of wheat varieties in Huang-huai winter wheat region. The wheat anther length is crucial organ for seed formation; long anther possesses the better ability of seed and deal with unfavorable climate such as late spring coldness. TaGS2 is an important gene controlling nitrogen utilization in bread wheat. In this study, the 90 K Illumina iSelect array was utilized to identify polymorphic SNPs in the genomes of bread wheat genotypes. In particular, the aims of this study aimed to(1) analysis the genetic diversity of wheat varieties from Huang-huai winter wheat region;(2) identify the SNP markers associated with the length of wheat anther by performing the GWAS;(3) dissect important agronomic traits associated with TaGS2 haplotype. The major results are as follow:1. In this study, the genetic diversity was conducted based on 144 bread wheat varieties and high-density SNP markers. The results showed gene diversity ranged from 0.29 to 0.43 with mean value of 038, the polymorphism information content(PIC) ranged from 0.24 to 0.38 with mean value of 0.30, in the level of genomes they both presented the trend of genome B>genome A>genome D. The analysis of population structure indicated five subpopulations appeared in Huang-huai winter wheat based on Structure, UPGMA and principal coordinate analyses. The results of clustering were positively associated to some extent with genetic relationship and geographic eco-type. LD analysis revealed LD decay of the whole genome was approximately 8.76 cM, the genome D had the highest distance of LD decay, followed by the B genome and genome A had the shortest distance of LD decay.2. Genome-wide association study(GWAS) was conducted for anther length on a set of 305 elite wheat lines evaluated during 2013-2015 seasons in two different environments. The mapping panel was genotyped through high-density SNP markers. GWAS using 18763 SNPs identified seven stable markers associated with anther length of wheat. The loci mainly distributed over the chromosome 3A, 3B and 7B, they could be candidate genomic regions of anther length and will be further validated. In addition, several positive correlations between anther length and grain weight per spike were observed in this study.3. The 278 elite varieties and 57 introduced varieties in this study were used to dissect the distribution frequencies of TaGS2 allele and analysis the association between major agronomic traits and TaGS2 haplotypes. The results showed that the frequencies of major haplotype presented different distribution in those materials, TaGS2-A1 b, TaGS2-B1 b and TaGS2-D1 a were favorable haplotypes, but the haplotype of TaGS2-A1 b and TaGS2-B1 b showed a downward trend. In the heading date and plant height, TaGS2-A1 b was a favor haplotype, TaGS2-D1 a was also an elite haplotype in spikelet improving grain weight per ear. In the study, genetic diversity of those wheat varieties had a reducing trend, so more attention were paid to introduced varieties and landrace. |
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