Genetic Relationship And Geographic Source Of Invasive Species Alternanthera Philoxeroides In China And Japan

Alligator weed(Alternanthera philoxeroides(Mart.)Griseb.)is a global invasive species native to South America.It is one of the first most harmful invasive plants identified by the Ministry of Environmental Protection of China.According to Chinese literature,alligator weed was introduced into China as forage plant in 1930 s.However,there were no any records for alligator weed in Japanese literatures until1990 s.Thus,the genetic relationships between Chinese populations and Japanese populations have been unclear.Here,we used molecular marker techniques to analysis the genetic relationships among different populations of alligator weed,including genetic and epigenetic structure among populations.We also included native populations from Argentina to explore the most possible source populations of those in Japan and China.Our results showed that:(1)The nine pairs of AFLP primers produced 573 loci and indicated no polymorphism.This uniform genetic background suggests that there were common source population for Chinese and Japanese alligator weed.(2)The five pairs of MSAP primers produced 258 loci,among which 131 epi-loci were polymorphic.About 87% of the total variations of DNA methylation were among populations in Japan,and 60% in China.The difference in DNA methylation between China and Japan was 21%,indicating that there are significant differences in epigenetic composition among Chinese and Japanese populations.(3)Contrary to the genetic unity of invasive populations,there were abundant genetic variations in the native populations from Argentina.The four pairs of AFLP primers produced 251 loci and 209 were polymorphic.The percentage of polymorphism was 83.3%.(4)To explore the possible geographic origins of the Japanese and Chinese populations,all the AFLP markers were pooled together and analyzed.The results of PCo A,Structure analysis,and Neighbor-joining tree suggested that thepopulation of Yala jujuy in Argentina was mostly closed to those in China and Japan.These results indicated that the populations of alligator weed in Japan and China had the same genetic composition,which might be from Yala jujuy in Argentina.There were significant epigenetic variations among populations,which may result from responses to different environments.These data are useful for effective control and management of invasive alligator weed.