华中特有珍稀植物裸芸香的AFLP遗传多样性分析

采用选择性扩增片段多态性(AFLP)方法对华中特有单种属植物裸芸香(Psilopeganum sinense)的8个自然居群的遗传多样性进行了检测与分析。结果表明:裸芸香的遗传多样性较低,且居群内遗传多样性显著低于物种水平遗传多样性。筛选出的5对引物共得到180个位点,76个为多态位点,多态位点百分率为42.2%,8个居群多态位点百分率为:3.3%～16.7%,居群平均多态位点百分率为9.4%;8个居群Nei多样性指数为0.01987～0.06987,Shannon’s多样性指数为0.0197～0.0816。居群间分化系数Gst=0.5069,居群间基因流为0.2432,不足以维持居群间的基因交流及现有的遗传结构。AMOVA分析表明总遗传变异的13.17%存在于4个地理区域之间,50.45%存在于地理区域内的居群间,36.38%的遗传变异存在于居群内个体间。NTSYS分析表明遗传距离与地理距离不存在相关关系。UPGMA聚类结果表明长江南北两岸的居群并没有产生明显分化。最后,分析了裸芸香的濒危原因并提出了有效的保育措施。

Analysis of AFLP Variation of the Endemic and Rare Species Psilopeganum sinense in Central China

AFLP variation of 164 individuals of eight natural populations of Psilopeganum sinense,an endemic and rare plant of Central China,was analyzed to investigate the genetic variation and genetic structure of the species.A moderate low genetic diversity was observed in the species and average variation of populations significantly lower than the variation of species level.A relatively low level of genetic diversity was observed in the species,and the genetic diversity within populations was significantly lower than that within the species.Five AFLP primers produced 180 bands,of which 76 were polymorphic,accouting for 42.2%.The percentage of polymorphic bands of eight natural populations was 3.3%-16.7%,respectively,with an average percentage of 9.4%.The Nei's gene diversity of eight natural populations was 0.01987-0.06987 and the Shannon's Information Index was 0.0197-0.0816.Average of Nei's gene diversity was 0.03420,and average of Shannon's Information Index was 0.0510.They were all lower than the average of species of the world level,but were higher than the average of the endemic species level.The average of Nei's gene diversity and Shannon's Information Index was 0.03420 and 0.0510 respectively,which were lower than the average of species in the world level but higher than the average of endemic species.In addition,Gst was 0.5069,which indicated that high population differentiation occurred.Analysis of molecular variance(AMOVA) of 164 individual revealed that 13.17% genetic variation was among the populations of four geographical regions and 50.45% genetic variation among the populations within the four regions;and 36.38% of total variance was distributed within populations.Nm was 0.2432,which implied that the gene flow was not enough to maintain gene exchange and current genetic structure.The result of UPGMA cluster showed that eight natural populations were genetically clustered in two groups,of which one was Yanduhe population and the other included the remaining seven populations.Mantel analysis of NTSYS indicated that genetic divergence was not correlated with geographical distance.At last,we analyzed the cause why P.sinense was endangered,and we concluded two main factors as follows.One was low genetic diversity that maybe due to bottleneck effect,inbreeding depression and the absent of natural selection,the other cause of population decline of P.sinense appeared to be from human disturbance.In correspondent with this,we proposed some effective strategies to conserve the species.