Using ISSR Marker To Analyze Genetic Resources Of Quercus Variabilis

Quercus variabilis is endemic in China with huge economic and ecological value.There are plentiful resources for oriental oak, but historical reasons and excessivedestruction have led to the secondary forests of the only existing, the geneticimprovement of Quercus variabilis has become a top priority. The ISSR reactionsystem and thermal cycling conditions of Quercus variabili are established viasingle-factor experiment. Based on the optimized reaction system,the genetic diversityof plus tree half-sibling families of Quercus variabili are analyzed by ISSR marker.Aiming to reveal the genetic variation of families of Quercus variabilis at themolecular level and compare with the clustering results of groups of Quercusvariabilis on the basis of morphological marker,explore the correlation between thegenetic relationship in groups and families of Quercus variabilis and geographicalsource in order to provide the basis for the collection and protection of finegermplasm resources,genetic improvement,the formulation of breeding strategy. In themeantime, ISSR marker linked to the loci related with the traits of growth rate in Q.variabilis are revealed by ISSR molecular marker with bulk sergeant analysis,this laysthe foundation of objective traits in Q. variabilis of quickly and efficiently earlyidentification and selective breeding indirectly by molecular marker.The main resultsare as follows：1. The ISSR reaction system of Quercus variabilis included a total volume25μLcontaining2.5μ L10×Buffer,30ng template DNA,1.5U Taq DNA polymerase,2.5mmol·L-1MgCl2,0.6μmol·L-1primer,0.3mmol·L-1dNTPs. Thermal cyclingconditions were as follows: denaturation1min at94℃;35cycles of30s at94℃,60sat51.5～59.0℃,2min at72℃; and a final extension of5min at72℃at the end ofthe amplification.2. The plus tree half-sibling families of Quercus variabilis were analyzed with apolymorphism percentage of89.6%, the Shannon information index（I）was0.47andNei’s gene diversity index（h）was0.32, the mean effective number of alleles and themean observed number of alleles were1.56and1.86, respectively. It suggested that the families of Quercus variabilis had a high level of genetic diversity.3. In the dendrogram of cluster analysis on five groups of Quercus variabilis onthe basis of ISSR marker,five natural groups were clustered into two sorts in theclustering diagram, Ningqiang population,Louguantai population and Taibaipopulation from Shanxi province were classified as a sort while Baotianmanpopulation and Xinyang population from Henan province were classified as a sort. Ithad certain genetic similarity between closed groups geographically while it hadgeographical isolation and genetic differentiation between remote groupsgeographically.Genetic relationship was divided basicly according to the geographicaldistribution.The clustering results of Quercus variabilis on the basis of morphologicalmarker were different from the ISSR marker.4.44families of Quercus variabilis were clustered into five groups when thesimilarity coefficient was0.62in the clustering diagram while the results of principalcoordinates analysis was the same with the results of cluster analysis basicly.Thefamilies originated from the same place and the closer geographic distance did’tdistribute in the same group totally. It indicated that there was no strict relationshipbetween the variation of the families of Quercus variabilis and geographic origin.