Genetic Analysis Of Dendrobium Sinense(Orchidaceae) Based On ISSR,Endemic To Hainan

Dendrobium sinense (Orchidaceae), an endangered species endemic to Hainan Island, occurred only in the mountain-woodland(above altitude1000m) of Hainan Island in China. In recent years, Dendrobium sinense suffered serious damage due to human activities and geographical factors of habitat fragmentation. It is imminent to protect the appropriate group. With the development of molecular biology, molecular marker technology because of its high stability, the rich amount of information and the advantages of broad comparability between different groups, break through the morphological marker, cytological marker to the expression type tags such as for population genetics research provides a good and reliable means of molecules.Using inter-simple sequence repeat (ISSR) marker, the genetic diversity and population differentiation in eleven Dendrobium sinense natural populations from Hainan Island was analyzed to explore the genetic diversity and endangered mechanism at molecular level and to formulate conservation strategy. The main results are as follows:(1) Using three kinds of improved DNA extraction methods including improved CTAB, improved SDS and improved PEX methods to extract DNA from fresh Dendrobium sinense leaves, the results showed that the improved PEX had good effect on DNA extraction, and meet the requirements of subsequent molecular experiment.(2)10ISSR primers were selected from the100ISSR universal primers were used for11natural populations, the results showed that high genetic diversity was found between DongWu and Shi Feng populations which belong to BaWang mountain, second peak of WuZhi mountain, YingGe mountain. The four populations which has a strong vitality and competitiveness are more likely to resist the adverse impact of the external environment. Low genetic diversity was found between HeiLing and second peak populations which belong to JianFeng mountian, LiMu mountian. They hard to resist the adverse impact of the external environment.(3) The results of ISSR AMOVA analysis showed that the variation in11Dendrobium sinense populations was84%respectively, and variation between11Dendrobium sinense populations was16%respectively, the results is similar to Popgene analysis. Thus, the variation of Dendrobium sinense is more distributed in populations, less occurred between them.(4) Using ISSR molecular markers analysis the gene flow in11populations of Dendrobium sinense,, the results showed gene flow in11populations of Dendrobium sinense was2.0336, the results was greater than1. The results showed that, the11populations of Dendrobium sinense have effective gene flow, which can not only prevent the formation of isolation but also can prevent differentiation among the populations.(5) Cluster analysis was carried out by UPGMA method using MEGA, the results showed, two populations of JianFeng mountain, LiMu mountian and YingGe mountian, two populations of WuZhi mountian, two populations (DongWu and ShiFeng) of BaWang mountain, they were respectively clustered together firstly, the results is similar to Popgene analysis.(6) Analysis on the genetic diversity of Dendrobium sinense according to the there factors of epiphytic height, host, altitude of the population, shows that there is a higher genetic diversity about the epiphytic Dendrobium sinense on myrtaceae, ericaceae and theaceae Dendrobium sinense shows the highest genetic diversity on the epiphytic height ranging from3m to4m, altitude of the population from1200m to1400m.(7) It is important to protect the habitat continuity, because this will help to create the effective gene flow when habitat fragmentation is happened by nature disaster. Keeping the effective gene flow between the populations of Dendrobium sinense is important for their protection, which will prevent genetic differentiation between the populations.