Assessment Of RAPD And AFLP-Based Genetic Variation In The Populations Of Picea Asperata Mast

Based on field investigations and analysis of the natural distribution of Picea asperata Mast, in P. R. China, ten populations of P. asperata (Chuanpan(CP), Linpo(LP), Rewugou(RWG), Baxi(BX), Tiebu(TB), Dalu(DL), Xiaojin(XJ), Aba(AB), Heishui(HS), Zhuoni(ZN))were selected and investigated. Genetic diversities were estimated and compared at DNA level based on RAPD and AFLP. Main results obtained are as follows:(1) The genetic diversity of ten natural populations of P. asperata was studied using RAPD markers. A total of 160 reproducible fragments were produced by the ten primers. Mean number of fragments per individual was 114.7. Altogether 120 fragments were polymorphic among the ten populations, but none of them were found to be population-specific. Nei's expected heterozygosity (He) ranged from 0.233 to 0.269. The average of Nei's expected heterozygosity across populations was relatively low to moderate, equaling 0.247. The highest level of diversity was detected in population RWG and the lowest diversity in population TB. The analysis of molecular variance revealed that the coefficient of gene differentiation among populations based on F_ST and the unbiased estimate Φ_st equaled 0.224 and 0.290, respectively. Such high values indicate that there is significant differentiation among populations. Gene flow between populations is 0.866.(2) In the present study, ten natural populations of P. asperata were studied using AFLP markers to investigate the population genetic structure and the level of genetic diversity. A total of 210 reproducible fragments were produced by the twoprimers-pair. 142 fragments were polymorphic among the ten populations. Nei's expected heterozygosity (He) ranged from 0.218 to 0.260. The average of Nei's expected heterozygosity across populations was relatively low to moderate, equaling 0.239. The highest level of diversity was detected in population CP and the lowest diversity in population TB. The coefficient of gene differentiation among populations, based on the estimate Fst and the unbiased estimate &sh equaled 0.207 and 0.231, respectively. Such high values indicate that there is significant differentiation among populations. Gene flow between populations (Nm = 0.96) is relatively limited.(3) Peripheral populations have reduced genetic variation compared to core populations in P. asperata. The strong inter-population differentiation of P. asperata could result from several factors, including restricted gene flow between populations. Habitat fragment and variation in environmental conditions in different populations may be another factor attributing to the high level of genetic differentiation among populations of P. asperata. In addition, it was discovered that the geographic distances were not correlated with the genetic distances between the populations of P. asperata.