Construction Of SSR Molecular Genetic Linkage Map And Identification Of QTLs For Main Traits Of Tetraploid Hybrid Wheatgrass

Agropyron is the perennial in Triticeae of Gramineae, it has characteristics of wide adaptability, strong resistance, high yield and good quality, which is also the important genetic resource to improve wheat crop varieties. In the present study, using200F2individuals of tetraploid hybrid wheatgrass as mapping population, we constructed a genetic linkage map of tetraploid wheatgrass based on SSR markers, and identified QTLs for11important agronomic traits such as height, stem-leaves rate of weight and the dry of single plant. It lays the foundation for future gene cloning, function analysi, and molecular marker assisted breeding of the main traits of wheatgrass. The main results were as follows:1. The SSR primers were selected with genomic DNA of one of F2individuals of tetraploid hybrid wheatgrass, and the parents A. mongolicum and A. cristatum cv.Fairway. A total of32polymorphic SSR primer pairs were screened from238SSR primers, which were then used to amplify200F2individuals of mapping population and obtained180polymorphic loci, with an average of5.36loci each primer pair.2. A total of30markers of all180polymorphic markers deviated the Mendel separation ratio, accounting for13.9%of the total loci number. It is suitable to construct the genetic linkage map because of the few biased markers.3. We constructed a genetic linkage map of tetraploid hybrid wheatgrass including161SSR makers and distributed on7linkage groups. The markers number of linkage groups ranged from11to41, and the length of that ranged from52.7to184.2cM. The map length was707.4cM, with the average distance between markers of4.39cM. It is a relatively high-density map. The maximum and the minimum length of all the7linkage groups were linkage group1and5, respectively.4. The11agronomic traits in F2mapping population of tetraploid hybrid wheatgrass such as plant height, stem-leaves rate of weight, the dry weigh of single plant and tiller number showed normal distribution, and there are significant correlation between different traits.5. We identified QTLs for11important agronomic traits of tetraploid wheatgrass, and a total of19QTLs were detected on5linkage groups, explaining the the phenotypic variation from5.7%to11.1%. On linkage group1, one QTL for individual stem diameter, one QTL for stem-leaves rate, and two QTLs for dry weigh per plant were identified. On linkage group2, one QTL for leaf number, one QTL for leaf width, one QTL for panicle length and two QTLs for tiller number were detected. On linkage group3, one QTL for plant height were mapped. On linkage group6, three QTLs for fresh weight per plant were detected. On linkage group7, one QTL for panicle length, two QTLs for panicle width and three QTLs for leaf length were mapped. In addition, there were not QTLs on Linkage group4and5.