Study On Biodiversity Of The Natural Populations And Ex-situ Conservation Strategy Of Sinocalycanthus Chinensis

Sinocalycanthus chinensis is a deciduous shrub of Calycanthaceae,Sinocalycanthus genus which has survived from the tertiary.As a second-grade protected wild plant in china and the only representative in the genus Sinocalycanthus,S.chinensis holds a special taxonomic status and high research value in system evolution field.New cultivars has been produced by crossing it with calycanthus floridus,the species belongs to calycanthus genus.S.chinensis inhabits narrowly in eastern or northwestern area of Zhejiang province.In the past forty years,the germplasm resources of S. chinensis were destructed greatly due to human factors and tourism development.Though most natural populations of S.chinensis have been conserved in Natural reserve,but the community of high canopy density do not favor it and the populations lead to a great regression.It has been detected that no genetic variation in the introduced population of S.chinensis in Tianmushan Natural reserve,shows that the ex-situation do not conserve its genetic diversity effectively and should not be considered as a success ex-situation of this endangered species.In this study,we conducted a series survey to habitat and resource of S.chinensis in its distribution area,analyzed the structure and dynamics of its natural population.On the basis of phenotypic and molecular marker data,sampling strategy of biodiversity as well as the suitable ex-situation conservation strategy was established.The main results were as follows:1.By field survey in Zhejiang,Anhui Province of S.chinensis distribution area,we summarize its habitat as follows,lies in north or northwest slope of a mountain,over 400m altitude,with high humidity,moderate light,soil pH value range from 4.5 to 5.6.The environmental factors play an important role in its distribution and widespread.2.The population structure and spatial distribution pattern analysis revealed that there were abundant seedlings but the population structure fluctured.The mortality rate significantly increased to the peak of 96.1%near ageâ…¥and the survival curve tend to be Deevey typeâ…¡.With the age increased,the spatial distribution patterns presented the same trend from clusting to random among different populations.The interspecies and interspecific competition is one of the cause which lead S. chinensis to be an endangered species.3.22 phenotypic traits were investigated by sample 8 populations.The results shows that significant variation existed among and within populations of S.chinensis.The outer petal color could be distinguished into four group,white,baby pink,pink and dark pink.The proportion among populations is different.There were a great correlation between longitude and latitude to flower diameter,floral shoot length,outer-perianth length,ratio of length to width,the weight and length of seed. The leaf length and number of fertile stamen varied with the content of organic matter and hydrolyzed nitrogen of soil.4.By using inter-simple sequence repeat(ISSR) marker technique,the genetic diversity of 8 populations was studied.The results showed that at species level,the percentage of polymorphic loci(P) was 63.86%,Shannon's index(h) 0.2687,and Nei's gene diversity(I) was 0.1713 while at population level,they were 31.63%,0.1805,0.1234,respectively,indicating a low level of genetic diversity.The gene differentiation coefficient(G_st 0.2985) suggested low genetic differentiation among populations and high genetic diversity within populations.5.According to the UPGMA cluster analysis on basis of phenotypic and molecular data,the 8 investigated populations could be divided into two groups.There was a great correlation between phenotypic and genetic differentiation to the geography distance.The distribution pattern of variation in S.chinensis natural population exhibited to be continuous.6.The sample strategy of genetic biodiversity conservation was established based on data of ISSR detected by 255 individuals of 8 populations and phenotypic as well,which includes(1) 6 populations (2)30%sampling proportion.7.The water content of soil and light density has a significant influence on growth of S.chinensis and the physical index differed correspondingly.Under high light density(100%full day light) or at drought soil(10%water content),the lipid peroxidation lead to malondialdehyde(MDA) accumulated which induced superoxide dismutase(SOD) and peroxidase(POD) activities significantly increasing. Shade could reduce the injury of lipid peroxidation while increasing water content(25%,45%) could enhancing the ability of tolerating high light density.The best combination of water content of soil and light density were of middle light density(50%full day light) and 45%water content,high-middle light density(25%full day light) and 25%water content.8.Ex-situ conservation was conducted by sowing seeds collected from 120 individuals of 6 populations.Germination time lasting near to 16 weeks and the average germination rate was about 65.09%.The seeds from Tiantai population geminated earlier than other 5 population's near to Lin'an city.