Study On Genetic Diversity Of Camellia Japonica Population Based On CDDP Molecular Marker

Shandong province is the northern boundary of camellia natural distribution area in China.Camellia in this area has strong cold tolerance,high ornamental and economic value.It’s a precious germplasm resource for camellia breeding.At present,its natural population only exists in Daguan Island and Changmenyan Island of Qingdao,which is seriously damaged by human interference.In recent years,the protection of the existing individuals was quite effective,but the population has always been lack of young individuals,the survival of the situation is not optimistic.In order to understand and protect this precious plant resource,the community of camellia in Changmenyan Island where it is concentrated was studied and the genetic diversity of camellia populations in two islands was analyzed by CDDP molecular marker technique.The following conclusions are drawn:1.The community structure of camellia was simple.It is seriously disturbed by human being,and low frequency components account for a large proportion.The community can be divided into three layers.Arbor layer is mainly artificial introduced plants such as Robinia pseudoacacia,and the canopy density is not high.Camellia plays an important role in shrub layer.In many places where lack of tree layers,it exists as a constructive species shows some characteristics of subtropical evergreen broadleaved forest.Herbaceous plants are abundant and interlayer plants are simple.2.A 20 L CDDP-PCR reaction system containing 2×es Taq master Mix（dye）10μL,10 pmol?μL^-11 primer 1μL,40 ng?μL^-11 DNA template 2μL and ddH₂O 7μL was constructed.3.The percentage of polymorphic loci（PPLs）in each population was between 56.76%and 83.78%,with an average of 71.85%.The number of effective alleles among individuals in each population was between 1.3693 and 1.4698,with an average of 1.4157 and the genetic diversity index of Nei’s was between 0.2135 and 0.2859,with an average of 0.2436.The Shannon information index ranged from 0.3570 to 0.4331,with an average of 0.3690.The Shannon information index is higher than the average value of the perennial,broad and cross plant populations obtained from Nybom’s statistical.It shows that camellia has abundant genetic diversity.4.The genetic distance（GD）between the 6 populations was 0.0277 to 0.1208,with an average of 0.0719.The Genetic similarity coefficient（Gs）was between 0.8862 and 0.9727,with an average of 0.9309.The genetic diversity index of Nei’s in population（Hs）was 0.2435,and the coefficient of genetic differentiation（Gst）between populations was 0.1525.The value of Nm was 2.7785.The genetic similarity of several populations is high,and they should have the same origin and the isolation time is not long.Because of the characteristics of insect-pollination,they maintain frequent gene exchange（Nm>1）,and there is certain genetic differentiation among the populations.5.The genetic diversity of camellia population in Shandong Province is relatively high,and the existing resources should be mainly protected in situ.According to the physiological characteristics of camellia,the canopy density of community tree layer should be increased appropriately to create suitable habitat for camellia and avoid man-made destruction to make it natural renewal.Young individuals should be reseed at the right moment.Because of the vulnerability of island habitats,relocation conservation is also an important initiative.The population of the two islands is small in size and covers a lot of genetic diversity.Germplasm should be collected and protected comprehensively,and the research and practice of the return of artificial reproduction individuals in the field should be carried out.