Association Mapping Of Accumulation And Remobilization Of WSC Regulated By Drought In Wheat During Grain-filling Stage

Wheat yield was not only related on the photosynthetic products, but also more dependent on the water soluble carbohydrates—WSC which temporarily stored in the vegetative organs at the late developmental stage under drought condition. Therefore, it has important scientific value and practical significance to do the further exploration of the physiological and genetic basis of WSC remobilization and redistribution to compensate the grain filling, and to select and explore the favorable alleles for the traits associated with WSC accumulation and remobilization.In this study, 120 wheat accessions with different characteristics of drought resistance were selected as experimental materials, then use 100 pairs of SSR primers covered all the genomes to analyze population genetic structure, lastly association mapping of WSC accumulation and remobilization regulated by drought was performed, to select markers closely associated with WSC accumulation and remobilization, and the aim was to provide theoretical basis for genetic improvement of wheat drought resistance. The results were as follows:1. WSC accumulation and remobilization in different organs of wheat during grain-filling stage were significantly or very significantly affected by water treatments, developmental stages, organs, genotype and the complex interaction of them. And all target traits showed wide variations(9.84%- 41.25%), high diversity index(0.728- 0.902) and low heritability(29.81%-51.07%). Through the cluster analysis of phenotype, screened totally nine wheat germplasms(980-4-1-1-2, 988-4-2-4-1, A80-3-1-1-3, B17-2-3-2-1, C14-14-1, Xifeng 20, Longyu 218, Longjian 103 and Longjian 196), which not only has high WSC content, but also to maintain a high remobilization rate in vegetative organs under drought stress, and can be used as ideal materials for wheat drought-resistant and molecular breeding.2. Using selected 79 polymorphic SSR markers to analyze the genetic diversity of wheat population. There were totally detected 433 alleles loci, allele No. ranged from 2 to 11 per SSR marker, and the average was 5.48; variation frequency of alleles ranged from 0.246 to 0.892 per marker, and the average was 0.488; genetic diversity index ranged from 0.180 to 0.825 per marker, and the average was 0.639; the polymorphism information content(PIC) ranged from 0.164 to 0.802 per marker, and the average was 0.592. The genetic diversity analysis of three genomes showed that B genome has the higher genetic diversity(0.568), and A genome followed(0.507), and D genome has the lower genetic diversity(0.379); The genetic diversity analysis of seven homologous groups showed that the sixth homologous group has the higher genetic diversity(0.700), while the seventh homologous group has the lower genetic diversity(0.601). The genetic diversity analysis of genetic diversity of 21 chromosomes showed that 1B, 6A and 6B have higher genetic diversity, and the genetic diversity indices were 0.786, 0.708 and 0.751, respectively. And 1A and 2D has lower genetic diversity, and the genetic diversity indices were 0.480 and 0.565, respectively.3. 120 wheat accessions had been divided into four categories using UPGMA clustering method by Power Marker v3.25, and four groups through population structural analysis by Structure 2.3.4. Wheat accessions which have the same geographical origin, tend to be devided into the same groups using both of the two methods.4. There were totally detected 19 markers have significant correlation(P <0.01) with WSC accumulation and remobilization by association analysis. And 12 markers were associated with WSC components content, can explain phenotypic variation ranged from 9.3% to 31.8%. 4 markers were associated with DM accumulation, can explain phenotypic variation ranged from 14.2% to 31.4%. 9 markers were associated with WSC components remobilization rate, can explain phenotypic variation ranged from 8.9% to 21.5%. And they have complexly temporal and spatial expression, which have different expression regulation in different developmental stages and organs. And some markers have ‘pleiotropic effect’—a marker can control several traits, such as barc170, barc184, barc216, cwm517, gdm86, gwm135, gwm285, wmc396 and wmc468, etc.