Development And Evaluation Of SSR Molecular Markers In Chinese Spring Wheat

Common wheat(Triticum aestivum L.),is widely cultivated hexaploid wheat(AABBDD,2n = 42)contains three diploid subgenomes.The initial allopolyploidization event is hypothesized to have involved the A and B genome donors,resulting in the extant tetraploid wheat(T.turgidum;AABB).This species subsequently hybridized with the D genome donor to form commom wheat.With the rapid development of bioinformatics,biological information technology will have a great effect on wheat breeding,like germplasm resources,the genetic analysis of evolutionary relationships,targeting genes,germplasm analysis of genetic diversity,quality and purity of fingerprint identification,locating important physiological trait gene,molecular marker-assisted selection breeding and other aspects of research,so large-scale development of genome-wide molecular wheat has an important mark on the scientific significance.Molecular marker technology has been widely used in constructing genetic map of wheat,germplasm analysis of genetic diversity,quality and purity of fingerprint identification,locating important physiological trait genes,molecular marker-assisted selection breeding and other aspects of research.Development of genome-wide molecular has important significance on wheat.Microsatellites or simple sequence repeats(SSRs),arranged across both prokaryotic and eukaryotic genomes,consists of up to dozens of nucleotides sequence of six nucleotides or less repeating units in series.In this experiment,the whole genome sequence of Chinese spring Wheat(CSW)in Genebank was searched.The obtained SSRs were surveied of the distribution and related molecular markers were developed.Then those markers were used to validate by Re-PCR program.Monomorphic markers were screened in CSW genome.Then 45 monomorphic markers were selected at random for verification.The results are as follows:(1)In the present test,we identified 364,347 SSRs from among 10,603,760 sequences of the CSW genome,which were present at a density of 36.68 SSR/Mb.In total,we detected 488 types of motifs ranging from di-to hexanucleotides,among which dinucleotide repeats dominated,accounting for approximately 42.52%of the genome.AG/CT,AAG/CTT,AGAT/ATCT,AAAAG/CTTTT and AAAATT/AATTTT were the most frequent repeats among di-to hexanucleotide repeats,respectively.The proportions of di-to hexanucleotide repeats on each chromosome,and even on the whole genome,were almost identical.2)295,267 SSR markers were successfully developed from the 21 chromosomes of CSW,which cover the entire genome at a density of 29.73 per Mb.All of the SSR markers were validated by Re-PCR;70,564(23.9%)were found to be monomorphic and 224,703(76.1%)were polymorphic.There were 45 monomorphic markers were selected randomly for validation purposes;24(53.3%)amplified one locus,8(17.8%)amplified multiple identical loci,and 13(28.9%)did not obtain any amplicon from the genomic DNA of CSW.(3)Custer analysis was generated based on the 24 monomorphic markers among three species of wheat ancestors and.20 wheat cultivars.This research indicates that monomorphic markers represented a promising source to increase the number of genetic markers available for the wheat genome.The results of this study will be useful for investigating the genetic diversity and evolution among wheat and related species.At the same time,the results will facilitate comparative genomic studies and marker-assisted breeding(MAS)in plants.At the same time,these monomorphic SSR markers will lay a solid theoretical foundation for the development of new wheat chips,the study on wheat molecular evolution,molecular marker-assisted selection and breeding of new germplasm research and so on.