Study On Genetic Diversity Of Native Arenga Engleri Becc. Populations In China

In recent years,due to habitat desruction and fragmentation,our native resources Arenga engleri is facing extinction.In this paper,based on the field investigation,note of specimen and literatures,the living environment of populations Arenga engleri were probed.The genetic diversity and population genetic structure of 10 natural populations of Arenga engleri,distributed in Fujian,Guangdong and Taiwan provinces,were studied by means of inter-simple sequence repeats(ISSR) markers. Based on the research of population genetic structure strategies,the conservation of these germplasm resources of Arenga engleri were also discussed.On the other hand, the result of ITS region sequencing proved the phylogenetic relationships among 8 species of Arenga.The main results are highlighted in the following:The optimized CTAB method was successfully used to extract the polysaccharide,phenols and pigment riched genomic DNA of Arenga.This method is widely used at present in our lab with satisfactory purity and quantity of the extract. The extracted DNA is suitable for ISSR-PCR.A total of 250 individuals representing 10 natural populations of Arenga engleri, were surveyed by use of 17 ISSR primers from 100,which generated 186 reproducible and clear amplification products.A relatively high level genetic diversity was detected in Arenga engleri species.Out of 186,184 loci with molecular weight from 200 to 2000 were polymorphic and accounted for 98.92%,Nei's gene diversity (h) and Shannon diversity index(I) were 0.3140 and 0.4778 in the species lever, respectively.Strong adoption,low environment select pressure and relatively few human activitied might be the causes of high genetic diversity of Arenga engleri.A relatively high level of genetic diversity was revealed:PPB=98.92%, He=0.3140(at species level);PPB=70.38%,He=0.2327(at population level).A relatively level of genetic differentiation was detected among populations with Nei's Gst analysis.Some differentiation may result from habitat fragmentation and barriers to gene flow.AMOVA showed that 29.70%of the genetic diversity resulted from differentiation among populations with remaining 70.3%residing within populations.That showed the majority of genetic variation occurred within populations and the high level of gene flow was among populations,dioecism,strong reproduction and high flow gene among some populations might be the main causes of low genetic differentiation of Arenga engleri populations.UPGMA cluster analysis indicated that the eight populations from Fujian and Guangdong province grouped together,whereas two populations from Taiwan clustered in another clade.These results,combined with other information about Arenga engleri,may provide a valuable basis for proposing conservation strategies.In situ conservation will be suitable for YK,YF,XL and FL populations with sufficient genetic diversity, while an ex situ strategy should be taken into consideration for XL,DL,TB and TN populations,where only a few individuals are left.According to the ITS sequence comparison among eight species of Arenga,the phylogenetic tree constructed by ITS sequence analysis was basically the same as traditional method,and most of the branch had high support degree.