Analysis On Genetic Diversity And Genetic Structure Of Castanopsis Tibetana Population

Castanopsis tibetana Hance, red Castanopsis, is an evergreen tree of Fagaceae family. It is one of the rare tree species with hard materials. With a wide distribution and abundant wild resources in China, Castanopsis tibetana becomes one of the most important rare timber species. In this study we analysised the genetic diversity and genetic structure of 111 samples from 9 Castanopsis tibetana populations from Hunan,Hubei and Fujian Province of China using ISSR molecular markers. We also analysed the genetic relationship among these individuals by cluster analysis method. The results of this research provided theory basses on the development and utilization of Castanopsis tibetana resources, collection and preservation of wild resources. The main methods and results are as follows:1. The optimal reaction system of ISSR (20μL) was found:30 ng template DNA,3 mmol/LMg2+,0.4 mmol/L dNTPs,0.75 U Taq DNA polymerase and 0.3 μmol/L primers.2.10 ISSR primers were screened out from 100 primers from UBC for amplifying 111 genomic DNA of Castanopsis tibetana using ISSR-PCR.158 intensive bands were amplified, among which there were 141 polymorphic bands. The polymorphic loci percentage (P) was 89.01%. Each primer amplified 13～19 band and the average number of bands from each primer was 15.1. The polymorphic loci percentage in different population was between 84.81% and 93.67%, YongShun (YS) showed the highest polymorphic loci percentage and ZhouNing (ZN) showed the lowest.3. Coefficient of genetic variation among Castanopsis tibetana populations (Gst) was 0.1855,so the great majority of genetic variation consist in populations and it was 81.45%.The gene flow was 2.1960 (Nm*>1) which was sufficient to prevent genetic drift and maintained the similarity among populations. The Nei’s genetic diversity index,Shannon’s information,number of total genetic diversity index,genetic diversity index are 0.3323,0.4920,0.4108,0.3346, it shows that Castanopsis tibetana population has high genetic diversity.4. Cluster analysis showed that Shaowu,Jianou,Jianyang,Pingnan and Zhouningpopulations clustered together. Enshi and Sangzhi population grouped together. Yongshun grouped together with Liuyang population. It was a further indicator that genetic variation of populations and its geographic pattern was basic consistency. Genetic distance among all the populations differed. The relationship of Shaowu and Jianou population was the nearest (only 0.0815), while Liuyang and Zhouning population was the farthest (0.1984). These results showed that the geographical distance was the major factor which affected the genetic variation.5. The correlation between environmental factors and the genetic diversity indexes of 9 Castanopsis tibetana populations was discussed in this study. A faintly negative relationship between altitude, average annual temperature and the genetic diversity indexes indicated that it might limit gene communion of the 9 Castanopsis tibetana populations. The results revealed that there was a significant positive correlation between slope position,average annual rainfall,latitude,longitude and the genetic diversity indexes. In a certain extent, the slope position,average annual rainfall,latitude and longitude were the dominant factors that affected the genetic diversity.