武夷山地伯乐树种群遗传多样性的ISSR分析

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

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%;HES:0.304 5;H:0.450 1),种群水平则较低(PPB:60.13%;HEP: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(Gst=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。

Bretschneidera sinensis Hems1. , 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% ; HEs ： 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% ; HEP ： 0. 238 1 ; H： 0. 347 5 ）, whereas the population in Baishanzu（BSZ） showed its own variability at the lowest level（PPB： 44.86% ; HE： 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. 6267, P 〈 0.05 ）. The high diversity would hold promise for conservation and restoration efforts to save the endangered species from extinction.