海南岛红树植物海桑遗传多样性的ISSR分析

海桑 (Sonneratia caseolaris)是海桑科红树植物 ,在我国仅天然分布于海南万宁、琼海、文昌等地。采用 ISSR分子标记技术对所有天然种群和海南东寨港红树林自然保护区引种的人工种群共 4个种群 86个个体进行了遗传变异分析。 11个引物共扩增出 2 39条带 ,其中 194条具多态性 ,多态位点百分率为 81.17%。在种群水平上多态位点百分率 4 0 .5 9%～ 5 0 .2 1% ,平均值为4 5 .71%。 Nei的基因多样性、Shannon信息指数在物种水平上分别为 0 .2 10 0和 0 .32 5 6 ,在种群水平上平均值分别为 0 .14 6 8和0 .2 2 10。 Nei的遗传分化系数 Gst和 AMOVA分析表明种群间已发生了较高的遗传分化。种群间的遗传一致度为 0 .90 11。估测的种群间的基因流为 0 .5 787。依据 Nei的遗传距离对不同种群进行 U PGMA聚类 ,聚类结果为横山种群 (HS)和东寨港种群(DZG)聚在一起 ,万宁种群 (WN)和琼海种群 (QH)聚为一类。Mantel检验表明遗传距离与地理距离之间有一定的正相关 ,但不显著。种群遗传多样性与环境因子间的相关性分析表明 :海桑种群遗传多样性水平与各环境因子间相关性均不显著。因东寨港引种种群的遗传多样性明显低于天然种群 ,为保护遗传多样性 ,应加强对琼海、万宁种群的就地保护和迁地保护工作。

Genetic diversity of mangrove plant Sonneratia caseolaris in Hainan Island based on ISSR analysis

Sonneratia caseolaris is a mangrove species belonging to Sonneratiaceae. The natural distribution in China restricted to Hainan Island. Sample leaves were collected from individuals of three natural S. caseolaris populations of Wanning (WN), Qionghai (QH) and Hengshan (HS) and one population at Dongzhai Harbor (DZG) introduced from nearby area. A total of eighty-six individuals were sampled. Eleven ISSR primers gave rise to 239 discernible DNA fragments of which 194 (81.17%) were polymorphic. The percentage of polymorphic bands at the population level ranged from 40.59% to 50.21%, with average of 45.71%. The Nei's genetic and Shannon's information index were 0.2103 and 0.3256 respectively at the species level, 0.1468 and 0.2210 respectively at the population level. Based on Nei's Gst value and analysis of molecular variance (AMOVA), it showed that higher genetic differentiation had occurred among populations. The genetic identity between populations was 0.9011 on average. Gene flow (Nm) was 0.5787. UPGMA cluster analysis based on Nei's genetic distance divided the populations into two main groups: WN and QH formed one group, while HS and DZG formed the other group. The Mantel test showed that genetic distance was positively correlated with geographical distance, but not significant. The correlation analysis showed that there was no significant relation between population genetic diversity level and environmental factors. Since the genetic diversity of DZG was obviously lower than that of natural populations, the effort of in situ and ex situ protection to QH and WN should be strengthened to conserve genetic diversity.