| Fragaria nilgerrensis Schltdl belongs to genus Fragaria L,family Rosaceae.It is an important wild strawberry resource in the southwest of China,and an important source of genetic improvement of cultivated strawberry.In this study,we collected 16 different populations of wild Fragaria nilgerrensis Schltdl resource in the southwest of China,then the genetic structure and genetic diversity of those resource were deeply studied by EST-SSR molecular marker technique at DNA level,which provided an important theoretical basis for the effective utilization and protection of wild Fragaria nilgerrensis Schltdl resources.The main results obtained in this paper are follows:1.Successfully developed Fragaria nilgerrensis Schltdl EST-SSRprimers.By screening 82537 UniGene sequences with a total length of 64777606 bp,a total of 11722 SSR loci were detected,distributed in 9785 UniGene,with an average of one SSR locus per 5526 bp.Single nucleotide,dinucleotide and trinucleotide were the main SSR repeats in Fragaria nilgerrensis Schltdl,accounting for 44.3%,32.3%and 22.4%,respectively,and tetranucleotide to hexanucleotide accounted for less than 1%.A/T,AG/CT and AAG/CCT were the dominant motifs of SSR,accounting for 43.6%,23.8%and 7.8%,respectively.Of the 125 pairs of primers synthesized,38 pairs of primers could amplify clear bands,and the amplification efficiency was 30.4%.Among them,21 pairs of primers had good polymorphism and reproducibility,accounting for 16.8%of the total number of primer design and synthesis.2.Analysis of genetic Diversity of Fragaria nilgerrensis Schltdl.Genetic diversity parameters at the locus level:The average allele number(Na)was 4.4375,the average effective allele number(Ne)was 1.8973,the average observed heterozygosity(Ho)was 0.4174,the average expected heterozygosity(He)was 0.1904,and the aroma information index(I)was 0.7905.The genetic diversity index(H)of Nei’s was 0.4006 and the polymorphic information content(PIC)was 0.4124.Genetic diversity parameters at the population level:The average allele number(Na)was 1.9766,the average effective allele number(Ne)was 1.5234,the average observed heterozygosity(Ho)was 0.2057,the average expected heterozygosity(He)was 0.2748,and the aroma information index(I)was 0.4225.The genetic diversity index(H)of Nei’s was 0.2573,and the average polymorphic loci were 10.3125,accounting for 64.45%.These results indicated that the 16 populations of Fragaria nilgerrensis Schltdl had rich genetic diversity,and the genetic variation of Fragaria nilgerrensis Schltdl.was very significant at the species level.3.Analysis of genetic structure of Fragaria nilgerrensis Schltdl population.The average F-statistic Fis,Fit,Fst and Nm at the locus level were 0.2049,0.4335,0.3687 and 0.4315,respectively,and the average Fst value at the population level was 0.33397.The results of AMOVA analysis showed that the genetic variation within and between populations were 65.96%and 34.01%,respectively.The results showed that 16 populations of Fragaria nilgerrensis Schltdl had significant genetic differentiation.The results of phylogenetic tree,PCA clustering and Mantel test showed that there was no significant positive correlation between genetic distance and geographical distance in 16 populations of Fragaria nilgerrensis Schltdl.Structure results showed that 16 populations of Fragaria nilgerrensis Schltdl were divided into two ancestral groups,and there was gene penetration between the two groups,among which the genetic background of LS population was the most complex. |
