武夷山地伯乐树种群遗传多样性的ISSR分析

伯乐树（Bretschneidera sinensis Hemsl.）为我国特有单型科珍稀濒危植物，具重要的科研价值。本研究采用ISSR分子标记对武夷山脉分布的5个伯乐树天然种群和1个移栽种群进行遗传多样性分析。结果表明伯乐树物种水平遗传多样性较高（PPB：75.70%；H_ES：0.304 5；H：0.450 1），种群水平则较低（PPB：60.13%；H_EP：0.238 1；H：0.347 5），MJY种群和BSZ种群分别是所有种群中遗传多样性最高和最低的。5个地理种群间遗传分化程度较高（G_st=0.218 1），原因可能源于伯乐树的繁殖方式及生境片段化，Mantel检验也证实了地理距离与遗传距离具有显著相关性（r=0.626 7，P＜0.05）。针对伯乐树种群遗传多样性现状，建议加强现有自然种群的就地保护，促进种群自然更新。

ISSR Analysis on the Genetic Diversity of Relic Plant Bretschneidera sinensis from Wuyishan Region

Bretschneidera sinensis Hemsl., with important research value, is an endangered species endemic in East and South Chin. We used inter-simple sequence repeat(ISSR) markers studied the genetic diversity within and among six populations of B.sinensis. The genetic diversity at species level was high(PPB: 75.70%; H_ES: 0.304 5; H: 0.450 1). However, relatively low genetic diversity existed within populations. Population in Minjiangyuan(MJY) exhibited the greatest level of variability(PPB: 60.13%; H_EP: 0.238 1; H: 0.347 5), whereas the population in Baishanzu(BSZ) showed its own variability at the lowest level(PPB: 44.86%; H_E: 0.173 6; H: 0.255 6). By the genetic analysis of the ISSRs, we revealed a relatively high level of genetic differentiation among populations by Nei’s gene diversity statistics(21.81%), Shannon’s information measure(22.79%) and analysis of molecular variance(AMOVA)(18.62%). The main factors responsible for the relatively high level of differentiation among populations were probably related to the predominant outcrossing reproductive system and recent habitat fragmentation, and a significant correlation was between genetic distance and geographic distance(r=0.626 7, P<0.05). The high diversity would hold promise for conservation and restoration efforts to save the endangered species from extinction.