Studies On Genetic Diversity Of Ziziphus Acidojujuba Germplasm Resources In Chaoyang Region Of Western Liaoning

Ziziphus acidojujuba is an important eco-economical tree specie unique to China.The lack of improved varieties is a limiting factor for industrial development,and selective breeding through germplasm resources investigantion is an important way for genetic improvement of Ziziphus acidojujuba.In this paper,with 53 Ziziphus acidojujuba germplasms and 8 Ziziphus jujuba varieties in Chaoyang area of western Liaoning as research objects,trough the observation of morphological characters（14 qualitative traits and 28quantitative traits）and SSR-PCR amplification experiments,the genetic diversity was studied and a fingerprint was established in order to provide scientific bases for exploration of Ziziphus acidojujuba germplasm resources and breeding of improved varieties.The main results were as follows:（1）The tested Ziziphus acidojujuba germplasms showed abundant genetic diversity in phenotypic traits.The variation coefficient of 28 quantitative traits ranged from 8.5%to104.5%,which suggested that the potential of Ziziphus acidojujuba breeding was great.The frequency distribution of the 14 qualitative traits also reflected the rich diversity of phenotypic traits in Ziziphus acidojujuba.By means of the combination of principal component analysis and cluster analysis,the tested germplasms were divided into three groups:The first group was a transitional type between Ziziphus jujuba and Ziziphus acidojujuba,characterized by medium-sized fruits and larger leaves;the second group was Ziziphus jujuba varieties;the third group was more similar to Ziziphus acidojujuba types,characterized by smaller fruits and mainly red fruits.（2）Using L₁₆（4⁵）orthogonal experiment,a SSR-PCR reaction system（20μL）suitable for Ziziphus acidojujuba was established:100 ng DNA templates,0.5μmol·L^-11 primers concentration,1.25 mmol·L^-11 Mg²⁺,1.5 U Taq polymerase and 0.3 mmol·L^-11 dNTPs.35 pairs of primers were selected from 60 pairs as Ziziphus acidojujuba SSR molecular markers.（3）The selected primers showed high polymorphism,with the N_A average of 8.6,the N_E average of 3.723,the PIC average of 0.661.The average of H_E was 0.698 and that of H_O was0.327,which showed that the heterozygosity of the tested germplasms was low.The genetic similarity coefficients were from 0.67 to 0.98,suggesting the genetic relationship of the tested germplasms was close and the genetic difference was small.（4）ULPMA and the STRUCTURE mathematical model cluster analysis based on SSR markers divided the tested germplasms into 4 groups and 3 groups respectively.The chi-square test showed that the two clustering results based on SSR markers were significantly correlated（Sig<0.01）,but the correlation between the clustering results based on phenotypic traits and on SSR markers was not significant（Sig>0.5）.（5）The DNA fingerprint of the tested germplasms was established by the combination of amplification bands of 6 pairs of primers,which were selected based on the principle that the number used were as small as possible and the amplification bands could be easily recognized.The 7 pairs of primers were BFU0183,JSSR88,JSSR102,JSSR239,JSSR222,JSSR262,and JSSR207,respectively.In summary,this research divided tested germplasms into three groups based on phenotypic traits,optimized SSR-PCR reaction system for Ziziphus acidojujuba,established the DNA fingerprint.Those provide scientific bases for the exploration,protection and selection of Ziziphus acidojujuba germplasm resources.