用AFLP技术分析紫茎泽兰的遗传多样性

Genetic diversity of Eupatorium adenophorum determined by AFLP marker

利用AFLP技术,选择EcoRI/MesI这一酶切组合,应用6对E+3/M+3引物组合进行选择性扩增,检测了24个地区的紫茎泽兰种群的基因组DNA多态性。共扩增出509个遗传位点,其中392个多态位点,多态率为77.01%。有效等位基因数(Ne)为1.50,Nei’s基因多样性指数(H)为0.29,Shannon信息指数(I)为0.42。并通过Jaccard的方法将电泳带矩阵转化为遗传相似性系数矩阵,进行了UPGMA聚类分析。结果表明:被检测的24个紫茎泽兰种群遗传多样性丰富;丰富程度与入侵定植时间有关,最早受紫茎泽兰入侵的云南省遗传多样性最丰富,变异最大,大致分为9个类群,紫茎泽兰的遗传基因可能对该省多样的气候条件或生境产生了明显的适应性变化;新入侵地区的则遗传多样性相对较低,并与云南省临近地区具有明显的种源地的地源性亲缘关系。子实的风媒传播是紫茎泽兰入侵的主要途径,样点间均具有明显的地源性亲缘关系;水媒也可能是该草传播的途径之一。紫茎泽兰可能首先从缅甸、越南、老挝经风媒入侵我国云南南部,逐渐扩散入侵中北部,又从云南北部和东部传入四川、贵州、广西、湖北等省。

Eupatorium adenophorum, a troublesome weed in the world, is one of the most important invasive organisms in China. Since it was first introduced to China in the 1940＇s, it has spread rapidly throughout southwcsternChina. Now it can be found in Yunnan, Guizhou, and Sichuan Provinces and in the Guangxiand Tibet Autonomous Region. Its invasion has caused seriously economic and ecological consequences for agriculture, forestry, and natural environments. The invasive characteristics of exotic organisms such as invasion pathway and dispersal are highly related to genetic diversity. A study on genetic diversity would be beneficial to predict the invasiveness and potential areas threatened by E. adenophorum, but little is known about the genetic diversity of this weed. AFLP （Amplified Fragment I,ength Polymorphism） technique was used to analyze genetic diversity of 24 different populations of E. adenophorum collected from 23 locations in China and one location in Australia. Genomic DNA was digested with EcoRI and MseI enzymes and amplified with six E＋3 and M＋3 Primer combinations. AFLPanalysis produced 509 scoreable bands, of which 392 （77.01%） were polymorphic. The effective number of alleles per locus （Na） of the 24 populations was 1.50, and the mean Nei＇s gene diversity index （H） was 0.29, the Shannon＇s information index （I） was 0.42, indicating that genetic diversity of this weed is very rich. Cluster Analysis based on the UPGMA method indicated that E. adenophorum was first introduced in Yunnan Province. Populations in Yunnan provinces showed the greatest genetic variability as all populations sampled in this province could be classified into nine groups. This indicated that genome DNA of E. adenophorum diversified due to adaptation to diverse climates and environments in Yunnan Province. In other newly-invaded areas, genetic diversity of E. adenophorum populations was less, and distinctly related to the geographically nearby populations collected from the place of Yunnan. Seeds of E. adenophorum are spread by wind and water resulting in close biogeographic relationships among the populations occurring in neighboring regions. These results suggest that E. adenophorum invaded the southern part of Yunnan Province from Myanmar, Vietnam and Laos on multiple occasions, and then spread to the central and northern parts. The established populations of E. adenophorum in Yunnan have provide the seed source which has spread the infestation into Guangxi, Guizhou, Sichuan, Tibet and even Hubei Provinces.