Studies On Conservation Genetics Of Sinowilsonia Henryi Hemsl.

Sinowilsonia henryi Hemsi., a deciduous trees of the genus Sinowilsonia belong to family Hamamelidaceae, lives in Shaanxi, Shanxi, Henan, Gansu, Hubei and Chongqing province. The species is of great scientific economic and ecologic value; however its nature population is hard to be found. To date, the species is regarded as endangered plant by both central and local government. Thus, the study on the genetic diversity, genetic structure, evolutionary potential, endangered mechanism and conservational stratagem will be of great value.In this study, the genetic diversity and genetic structure of S. henryi populations was studied using ISSR markers with the aims to illuminate the genetic backgrounds of S. henryi, analyze the mechanism of its endangerment, and come up with conservation implications. The results were as follows:To reveal the genetic diversity of S. henryi, the optimization CTAB methods was used to extract DNA from dry leaves of S. henryi, the pretreatment liquid was added in the conventional method of CTAB, and cleaned the abrasive plant tissue material. The purity and concentration of the DNA were tested. The results showed that the DNA could be well amplified, which was fully able to meet the demand of further experiments. The ISSR-PCR reaction system for S. henryi were set up by orthogonal experimental design in four levels of four factors (Mg2+, dNTP, Tag DNA polymerase, primer) respectively, a 10μL reaction system which containing 1.0mmol/L MgCl2,0.2mmol/L dNTP,1.U Tag DNA polymerase, 0.4μmol/L primer, 1.0μL 10×PCR Buffer, and 20ng DNA template was chosen. Based on the ISSR-PCR reaction system mentioned above,15 primers suit were selected for ISSR analysis on the genetic diversity of S. henryi.ISSR markers were used to analyze the genetic diversity and genetic structure of 14 natural populations of S. henryi in China.15 ISSR primers were used to detect 214 samples from 14 populations. A high polymorphism was detected at the species level(PPL= 72.47%, He= 0.2449,I= 0.3690), however it is low at the population level(PPL= 26.73%, He= 0.1025,I= 0.1480). Genetic differentiation detected by Nei’s genetic diversity analysis suggested 0.5857 occurred among populations. Gene flow was very limited with the value of 0.3537. That genetic variation among populations is higher than that within populations, and high genetic differentiation was found among populations. A significantly positive correlation between genetic and geographic distance was detected(r= 0.668, p< 0.01). Geographical isolation, gene flow and environmental fragment should be responsible for the present genetic structure of the species.In conclusion, the optimization CTAB methods was used to extract total DNA, and ISSR reaction system was established. ISSR markers were used to analyze the genetic diversity and genetic structure of S. henryi, showed that genetic variation among populations is higher than that within populations, and high genetic differentiation was found among populations. Thus, In situ conservation strategies were proposed based on the information and investigation of S. henryi in the habitat revealed by the study.