Studies On Genetic Diversity And Core Collection Construction Of Ziziphus Jujuba Germsplasm Resources Using AFLP And SRAP Markers

As one of the important fruit trees, Chinese jujube(Ziziphus jujuba Mill.) originated from China. It has very long culture practice history. Gremplasm resources of Chinese jujube are very abundant. The germplasm research evolved from morphological diversity to genetic diversity. The studies on Chinese jujube involved the fields of morphology, palynology, biochemistry and molecular biochemistry. At present, only a little of the evolvement connection and the phylogenetic relationships among cultivars had been known. Especially, we know nothing about the construction of core collection. In this study, genetic diversity in 177 Chinese jujube accessions from different regions was assessed using AFLP and SRAP makers. Then core collection of Chinese jujube was developed. The main results were as follows:1. The genomic DNA of Ziziphus jujuba was extracted by a modified CTAB method. The characteristic of this method was as follows: washing out most of polysaccharides and other secondary compounds with CTAB-free buffer before extracting DNA; adding the concentration of CTAB, adoption of 3% CTAB rather than 2% CTAB in the exaction medium; using of high concentration of salt prior to DNA precipitation with ethanol to remove residual polysaccharides. The isolated DNA was proved suitable for AFLP analysis.2. Seventeen AFLP primer combinations (EcoRI/MseI) selected from 120 primer combinations were used in this study, based on level of polymorphisms and the number of strong bands. A total of 577 bands were scored, of them 372 (64.47%)were polymorphic. The genetic similarity (GS) among 177 accessions ranged from 0.761 to 1.000. The genetic similarity between Suyuanling and Yuanling was the highest (1.000).On the other hand, The genetic similarity between Chentuozao and acidjujube1 was the lowest (0.761).3. The fingerprints of 177 accessions were established based on AFLP bands using 17 primer combinations. Some of them have unique band patterns, which can be used to their identification.4. Six SRAP primer combinations were used in this study. A total of 113 bands were scored, of them 62 (54.87%) were polymorphic. The genetic similarity (GS) among 177 accessions ranged from 0.727 to 1.000. 5. Cluster analysis using UPGMA (Un-weighted Pair Group Mathematics Average)method based on the data of AFLP, SRAP and AFLP+SRAP data displayed the genetic relation among the tested materials.6. The genetic relationship among some cultivars based on AFLP and SRAP data was analysed.7. According to the cluster result of AFLP+SRAP, three methods were used to construct core collection of 166 Chinese jujube germplasms. The number of polymorphic loci, percentage of polymorphic loci, observed number of alleles, effective number of alleles, Nei's gene diversity and Shannon's information index were compared, results proved that the method of stepwise reduce within groups was the best method and got 50 core collection of Chinese jujube. The core collection hold 30.12% samples of initial collection, the reserved rate of number of polymorphic loci and percentage of polymorphic loci reached 88.73%, the reserved rate of observed number of alleles, effective number of alleles, Nei's gene diversity and Shannon's information index were reached 96.14%,99.86%,98.30% and 97.20%, respectively. Those results demonstrated that the core collection can stand for initial collection excellently.