Genetic Diversity Of Germplasm Resources Revealed By SSR In Phoebe Bournei

Phoebe bournei is one of the rare secondary protected plants in China.It is not only an important timber tree species,but also has the function of landscaping.Due to the difficulty of natural regeneration and serious human destruction,the wild resources are gradually reduced.The genetic diversity of germplasm resources is of great significance to the protection and breeding utilization.In this study,high-throughput sequencing was used to develop the Genomic-SSR and EST-SSR markers,and the genetic diversity of 6 wild populations in Fujian province was analyzed by the developed markers,We also discussed the geographic variation pattern,Besides,the genetic differences among 39 excellent genotypes was detected.The main results are as follows:1.A total of 5,178,284 sequences were obtained by Illumina MiSeq sequencing of SSR enriched libraries,in which 4,758,764 were filtered with high quality.Using MISA software analysis,a total of 1,590,126SSR loci were obtained,of which single nucleotide,dinucleotide and trinucleotide were the dominant repeat types,and the polymorphism was preliminarily evaluated.The 100 primers were randomly selected and synthesized for PCR amplification,and the 10 primers with clear,stable,high repeatability and polymorphism were finally selected.2.The Illumina HiSeq sequencing was carried out to get the transcriptomes of xylem,phloem and leaf,and 151,729 unigenes with an average length of 542bp were obtained.Using MISA software,a total of35,972 SSR loci were obtained,of which single nucleotide,dinucleotide and trinucleotide were the dominant repeat types.The 120 primers were randomly selected and synthesized for PCR amplification,and the 7EST-SSR primers with clear bands,stable and high repeatability and polymorphism were selected.3.Genetic diversity and genetic structure of 6 wild populations were analyzed by the 10 genomic-SSRs.The Shannon information index?I?were between 0.0758 and 0.3309,the average effective number of alleles N_e was 1.5221,the total genetic diversity H_t was 0.2916,the genetic diversity within populations H_s was 0.1544,the genetic differentiation coefficient G_STT was 0.4705,and the gene flow N_m was 0.5628.The six populations can be divided into three classes,and no significant correlation was detected between genetic and geographic distance.4.Genetic diversity and genetic structure of the 6 wild populations were analyzed with 10 EST-SSRs.The Shannon information index?I?were between 0.316 and 0.612,the average effective number of alleles N_e was 1.630,the total gene diversity H_t was 0.406,the genetic diversity within populations H_s was 0.299,the coefficient of genetic differentiation G_STT was 0.263,and the gene flow N_m was 3.071.The 6 populations can be divided into five classes,and no significant correlation was detected between genetic and geographic distance.The wild populations have a certain level of genetic diversity.The genetic variation mainly came from within the populations.There was a certain degree of genetic differentiation,and there was the occurrence of gene exchange.5.The SSR analysis was performed on 39 excellent genotypes using10 genomic-SSRs.A total of 65 bands and 50 polymorphic bands were amplified,with a polymorphism ratio of 76.9%.The number of observed genes N_a was 1.7692,the number of effective alleles N_e was 1.4333,the Nei's genetic diversity index H was 0.2589,and the Shannon information index I was 0.3908,indicating that there were certain genetic differences among the 39 genotypes.Using UPGMA clustering,the 39 genotypes can be divided into 3 classes,the class?includes seven genotypes,class?includes 31 genotypes,and class?includes only 1 genotype.6.Based on the genetic diversity of germplasm resources,we discussed the strategies for protection and utilization.