Genetic Diversity Of Wild Apricot Germplasm Resources And Exploration Of Superior Germplasm

Wild apricot had a long history,which was widely distributed,mostly in wild or semi-wild state,and its germplasm resources were extremely abundant.It provided abundant material base for breeding high-quality seed of Wild apricot.Based on the investigation,collection and preservation of the germplasm resources in the distribution area of Wild apricot,the genetic diversity and exploration of superior germplasm were studied.It was aimed at providing the theoretical and technical basis for the identification,classification and evaluation of the germplasm resources of Wild apricot,and it also provided scientific basis for the work such as utilizing the resources and breeding high-quality seed of Wild apricot.The main findings were as follows:(1)The phenotypic traits of Wild apricot clones were rich in diversity.The variation coefficient of branch length was the largest,Shannon-wiener index of leaf length and nutlet thickness was the largest.Some indexes,such as branch length and branch width,were significantly related to the change of longitude and latitude.The differences of phenotypic traits among different provenances were significant.The phenotypic clustering result of Armeniaca sibirica was divided into 6 groups,and Armeniaca vulgaris var.ansu was divided into 5 groups.The results of phenotypic cluster reflected the characteristic of geographical provenances and phenotypic traits.(2)The simplified genome sequencing and primer development of Wild apricot were completed.The SSR-PCR reaction system was established and optimized.After the chloroplast genome sequencing was completed,131 genes were annotated,including 90protein coding genes,33 t RNA genes and 8 r RNA genes.Wild apricot clones showed high levels of genetic diversity on SSR markers.The N_A and N_E of Armeniaca sibirica were 7.382and 2.666 respectively,and the PIC was 0.561.The N_A and N_E of Armeniaca vulgaris var.ansu were 11.433 and 4.433 respectively,and the PIC was 0.670.SSR markers clustering reflected the differences between individuals in provenances and germplasm characteristics.Not only that,the clustering result had a very significant correlation with the provenance classification and clustering results of phenotypic traits.The genetic diversity among provenances was higher than that within provenance,and the genetic variation mainly came from within provenance.The fingerprints of Wild apricot clones were constructed by using 5pairs of primer amplification bands.(3)Population genetic structure based on STRUCTURE showed that Armeniaca sibirica and Armeniaca vulgaris var.ansu clones can be divided into 3 subgroups.This reflected the genetic background information of different clones and genetic diversity of provenances and phenotypic characteristics,which also had significant correlation with provenance classification,phenotypic clustering and SSR marker clustering.There was a wide linkage disequilibrium between SSR loci in Wild apricot.15 loci were associated with 10traits of Armeniaca sibirica,and 14 loci were associated with 11 traits of Armeniaca vulgaris var.ansu were tested.(4)According to the selection rate of 20%,42 Wild apricot clones showed better comprehensive traits.22 traits such as single kernel weight and single fruit weight can be used as comprehensive evaluation indexes.Main branch base angle,single leaf area,number of bouquet spurs and crown length of Wild apricot were the main factors that affect yield per plant,and the effect of basal angle of main branch on yield per plant was mainly direct.6clones were selected as excellent high yield types.5 clones were selected as the frost resistant type at flowering stage.The frost damage temperature,yield per plant and frost resistance of flower organs were preliminarily studied by artificially controlled frost.