Genetic diversity of Eupatorium adenophorum determined by AFLP marker
用AFLP技术分析紫茎泽兰的遗传多样性

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 southwestern China. Now it can be found in Yunnan, Guizhou, and Sichuan Provinces and in the Guangxi and 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 Length Po1ymorphism) 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. AFLP analysis produced 509 scoreable bands, of which 392 (77.01%) were polymorphic. The effective number of alleles per locus (N_a) 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.