Analysis Of Community Ecology And Genetic Diversity In Medicinal Plant Sarcandra Glabra (Thunb.) Nakai

Sarcandra glabra (Thunb.) Nakai, a kind of Chinese herbal medicine in common use, belongs to the genus of Sarcandra Gardn. in Chloranthaceae. At present, researches on S. glabra mainly focus on its chemical components, pharmacology, clinical exercises, etc. Presently with the rapid development of Chinese traditional and herbal drugs, requirements for wild medicinal plant resources grow day by day.In order to guarantee the sustainable usage of such medicinal plant, protection activities and researches on such wild resources have to be done urgently. From conservation biology viewpoint, we carried out basic researches including community ecology and population genetics on this wild medicinal plant. By using community survey by regular fieldwork we make quantitative classification by TWINSPAN of rank classification technology to make clear the species diversity in the communities and relationships between the communities and the environment gradients. Leaves from different populations as materials, and through CTAB method to obtain DNA , RAPD molecular marker was used to study the genetic diversity among populations of the species. We firstly discussed the optimum condition in RAPD reaction system, and then analyzed genetic diversity analysis on all populations. It aims at providing the scientific evidences for the protection, exploring and utilizing of this medicinal plant properly in future.Results of this paper show as followings:1) The 44 plots in S. glabra communities of Mt. Jinyun were classified into 7 associations by Two-way Indicator Species Analysis (TWINSPAN): Elaeocarpus japonicus+Symplocos setchuanensis+Itea chinensis+Dicranopteris pedata Association, Elaeocarpus japonicus+Neolitsea aurata +Stranvaesia tomentosa+Woodwardia japonica Association, Lindera kwangtungensis+Eurya loquiana+ Maesa japonica+Dryopteris erythrosora Association, etc.2)Results from TWINSPAN reflect obvious environmental gradients, such as integrative gradients including altitude, water, soil pH in,etc. The results show relationship between types of communities and environment gradients. From characters of these associations, such conclusion can be summarized: S. glabra likes to live in wet and rich soil under evergreen or deciduous broad-leaved forests. It is pointed out preliminarily that the best type of plant community for the growth of S. glabra is Castanopsis carlesii+Castanopsis fargesii+Stranvaesia tomentosa+Sarcandra glabra+ Arachniodes simplicor Association.3) The species diversity indices of 7 associations varied with the habitats and human interferences. The ordering of the species diversity of the 7 associations showed that the species diversity of the associations with better habitats and slight human interferences is relatively higher.4)In RAPD experiments, the optimum concentration of five important components such as Mg²⁺ , Taq DNA polymerase, primer, template DNA, and dNTP in 25μl RAPD reaction system were 2.5mmol/L, 1.0U, 0.4μmol/L, 60ng, 0.16 mmol/L respectively. Modified thermal profile consisted of an initial denaturation step at 94℃for 2 mins, followed by 40 cycles of 94℃for 30s, 37℃for 30s, 72℃for 80s, and a final exposure to 72℃for 10min. Then stored in 4℃for 10 mins.5)The total percentage of polymorphic loci in RAPD marker experiment is 93.26%. Genetic similarity coefficient among populations is more 90%. The level of genetic diversity for wild S. glabra is relatively higher. Among populations the genetic relationships are closer and gene flows are in a higher degree.6)Based on the research of S. glabra community ecology and genetic diversity, in-situ protection is of more direct and more important.