Qinling Region Of S. Sphenanthera Population Genetic Structure And Genetic Diversity

Schisandra sphenanthera Rehd. et Wils., belonging to the Schisandra Michx. of family Schisandraceae, is a woody and dioecious liane. It is used as an important medicinal plant in the world, and the ripe and dry fruits of Schisandra sphenanthera that named "nan-wu-wei-zi" have been a well-known traditional Chinese medicine. The species distribute in Shaanxi province, Shanxi province, Gansu province, and most states of the southern China. Since 2006, our laboratory have done a lot of investigations on the germplasm resources of Schisandra sphenanthera in some areas of Qinling mountain in Shaanxi province, Funiu mountain in Henan province, Longmen mountain in Sichuan province, Daba mountain in Shaanxi and Sichuan province, Taihang mountain in Shanxi province, Dabie mountain in Anhui province, Tianmu mountain in Zhejiang province, respectively, The results of investigations have shown that Shaanxi Province is a primary production area for Schisandra sphenanthera, and they dominate by wild, only a small amount of cultivars.In recent years, Schisandra sphenanthera has been over-exploitation and the wild resources have been decreased sharply going with the growth of market demand of "nan-wu-wei-zi". It is very important to evaluation of genetic diversity of Schisandra sphenanthera in Qinling mountain, because of lack of understanding about genetic background in this region. The population genetic structure and genetic diversity of three populations of Schisandra sphenanthera were studied in this paper based on morphological marker and ISSR molecular marker, it can provide reference for germplasm conservation and utilization for Schisandra sphenanthera in Qinling mountain. Main results obtained are as follows:1. There were abundant genetic variations in Schisandra sphenanthera. It has significant or very significant differences among populations and among individuals within population from research based on phenotypic variation. Overall, the mean phenotypic differentiation coefficient (VST) and coefficient of variability (CV) showed that the vegetative organs with 20.32% of CV and 17.74 % of VST have more genetic variation than the reproductive organs with 16.26% of CV and 8.96% of VST.But, there were some phenotypic differentiation. The stamen number (SN) has greater differentiation among populations with 27.28% of VST, and the peduncle length (PdL) also has a large variation values within populations, CV was 27.20%. The results of ISSR molecular markers also show that Schisandra sphenanthera has a high genetic diversity. Shannon's information index(I) and index of gene diversity (H) were 0.507 and 0.348 by square root method than 0.395 and 0.382 by Bayesian Method, respectively. 2. The descending order on the basis of the level of genetic diversity within populations were Taibai population (CV=17.97%; I=0.495, H=0.339), Zhashui population (CV=17.78%;I= 0.480, H=0.328), Huaxian population (CV=16.12%;I=0.459, H=0.312). The same clustering results were obtained from morphological markers and molecular markers, that is, three natural populations could be divided into two clusters, one was Huaxian population and Taibai population, the other was Zhashui population.3. About 90% of the total genetic variation occurred within populations in Schisandra sphenanthera, the genetic differentiation among populations was very limited (VST=0.1301,ΦST= 0.106,FST=0.082,GST=0.066,θST=0.052).4. There was a big gene flow (Nm) among populations in Schisandra sphenanthera. The estimated values of Gene flow (Nm) were between 2.108 and 4.558, Gene flow (Nm) was greater than 1, indicating the genetic differentiation among populations was not caused by genetic drift.5. The level of genetic diversity of the female plant (P=85.71%,I=0.500, H=0.344) and male plants (P=85.71%,I=0.506, H=0.347) was very similar, but there were phenotypic differentiations significantly in most of morphological traits, such as leaf width (LW), petiole length (PtL), number of secondary vein in the right side leaf (SVRLN), pedicel leaf (PdL), the largest petal length (LPL), the largest petal width (LPW), and so on.6. The biological characteristics of Schisandra sphenanthera, such as dioecy, wind-pollination or insect-pollination, wide-area distribution, were the main reasons for the formation of genetic diversity.7. The values of the genetic differentiation coefficients from different definitions were significantly dissimilarity, therefore, they should not be used for comparison directly. And the values of recessive allele and some parameters of genetic diversity were also quite different using the square root method and the Bayesian method.