| Peach[Prunus persica L.Batsch]is originated from China,and extended from Persia(now Iran)to Europe through the Silk Road in the centuries BC,and then spread to America in the 16th century.Currently,peaches are widely cultivated in temperate and subtropical regions around the world.After long-term domestication,peaches are divided into wild resources,genetic materials,local varieties,breeding varieties and strains.As a model plant for molecular genetic research of Rosaceae fruit trees,peach has great significance for its phenotype and genotype diversity evaluation.In this paper,on the one hand,indentificating phenotypic traits as well as measuring sugar and acid components were used to initially assess the polymorphism at the phenotypic level;on the other hand,the wild peach resources were tested by SSR-seq with SSR primers,according to 64 peach germplasm genome resequencing data,to assess the polymorphism at the molecular level.Objectively,assessing 114 wild peach combined phenotypic identification and SSR genotyping,in order to provide reference for the excavation and utilization of peach excellent germplasm.The main findings of this paper are as follows:1 SSR locus miningMISA software was used to perform SSR locus mining on 64 peach germplasm genome resequencing data in Perl language.This study only searched SSRs of mononucleotide,dinucleotide,trinucleotide and teranucleotide types(8 chromosomes,without scaffold).The order of SSR repeat motifs was:mononucleotide>dinucleotide>trinucleotide>tetranucleotide,occupying 58.59%,26.05%,11.12%and 4.24%of the total,respectively.At the chromosome level,The most abundant of SSR locus is the 1st chromosome(7181).The largest relative abundance of SSR loci is the 2nd chromosome(182.80/Mb).The polymorphic SSR locus accounted for 57.86%of the total SSR,and there were 252 SSR loci in 15 genotypes.2 Phenotype evaluation of wild peach resourceThis paper tested 114 wild peach resources,which expressed rich genetic diversities in phenotypic trait.Fruit traits(fruit shape,stylar end,fruit size,flesh color,flesh texture and stone adherence to flesh)also expressd rich diversity.Furthermore,this paper assessed the fruit traits by measurig sugar and acid components with HPLC.It is found that most of the test materials are low fructose/glucose type.In addition,wild peach resources differed greatly in stress resistance,and there were 8 resources with strong comprehensive resistance to fugal gummosis and perforation.114 accessions were clustered into five groups by phenotype traits,which were related to geographic origin as well as sugar and acid content.3 Genetic diversity analysis of wild peach resources based on SSRSSR primer pairs were distributed on genome resequencing datasets of 64 peach germplasm,and then selected 9 highly polymorphic SSR primers(Pp1-2,Pp1-4.Pp2-3,Pp3-3,Pp3-4,Pp4-5,Pp5-2),which were used to assess the genetic diversity of 117 peach germplasm.The average number of allele per locus is 14.56.The average of effective number of alleles is 6.28.The Nei’s genetic diversity index ranged from 0.64 to 0.88,with an average of 0.82.The genetic diversity index of these loci are greater than 0.50,indicating that the polymorphism is at a medium level.For each SSR pair,the observation of heterozygosity(0.31～0.78)is less than the expected of heterozygosity(0.65～0.88),indicating that wild peach resource population is low in heterozygosity.According to the cluster analysis,117 accessions were separated into three major groups,and were separated into three population in structure analysis.The results of the two classifications are basically consistent. |
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