Genetic Diversity And Molecular Phylogeography Of The Invasive Solidago Canadensis L.

The mechanisms underlying the success of biological invasion is one of the key spot and hot spot of invasion ecology. Genetic material is one of the most important determinator of the phenotypic traits of biotes. Exploring the genetic mechanism of biological invasion could elucidate why and how invasive plants succeed to invasive a new range. Solidago canadensis, a perennial herb plant belonging to Solidago genus in Asteraceae family, originated from Southern America and now widely invaded into China. S. canadensis populations were sampled along their expansion ways. Genetic diversity of S. canadensis L were analyzed using simple sequence repeat (SSR) and chloroplast simple sequence repeat (cpSSR) molecular markers. The molecular phylogenetic tree was drawed to predict the possible invasion routes. The results could provide basic references for the management and control of S. canadensis L.The optimized SSR PCR amplified reaction condition was:4ng template DNA,0.2mM of4×dNTPs,1×PCR buffer,1.5mM MgCl2,1U Taq polymerase and0.2mM of each specific primer in total20μL reaction mixture. The PCR products were analyzed on Fragment Analyzer Automated Capillary Electrophoresis System. The results showed that genetic diversity of S. canadensis L at species level was relatively high:the percentage of polymorphic loci(P) was100%, Shannon informative index (I) was0.4023, and Nei’s gene index (h) was0.2429. Genetic diversity of S. canadensis L in Wuhu population was the highest (P=100%,I= 0.3950, h=0.2418), and that in Wenzhou population was the lowest (P=91.84%,I=0.3402, h=0.2053). AMOVA anlysis shoed that the genetic differentiation coefficient (Fst) was0.0354, indicating that most of the genetic variation existed within populations, while little existed among populations. The estimated gene flow was as high as6.8128. The genetic genetic distance between population Wuhu and Hankou was the nearest (0.0078), while that between population Pudong and Wucang was the farthest (0.0510). Clustering analysis based on UPGMA showed that all the populations were clustered into two groups. Population Jiujiang and Pudong were clustered into one group. Population Nantong, Fuzhou and Lianyungang were clustered into one subgroup and the others were clustered into the other subgroup, then the two subgroups were clustered into the other group.The optimized cpSSR PCR amplified reaction condition was:4ng template DNA,0.3mM of each dNTPs,1×PCR buffer,2.5mM MgCl2,1.5U Taq polymerase (Promega Biotech) and0.15μM of each specific primer in total20μL reaction mixture. The PCR products were analyzed on WAVE4500DNA fragment analysis system. The results showed that genetic diversity of S. canadensis L at species level was relatively high:the percentage of polymorphic loci(P)100%, Shannon informative index (I)0.5843, and Nei’s gene index (h)0.2684. Genetic diversity of S. canadensis L in Fuzhou population was the highest (P=100%,I=0.9126, h=0.5116), and that in Hangzhou population was the lowest (P=80%, I=0.3285, h=0.1836). AMOVA anlysis shoed that the genetic differentiation coefficient (Fst) was0.2612, indicating that most of the genetic variation existed within populations, while little existed among populations. The estimated gene flow was1.4303. The genetic genetic distance between population Wucang and Hangzhou was the nearest (0.0227), while that between population Nanjing and Jiujiang was the farthest (0.6745). Clustering analysis based on UPGMA showed that all the populations were clustered into three groups. Hongqiao population and Taizhou population were clustered into one subgroup, then clustered with Nangjing and Putong into one group. Jiujiang population was the second group. Jingdezhen, Fuzhou, Wenzhou and Nantong populations were clustered into one subgroup, Hankou and Lianyungang were clustered into one subgroup. Hangzhou, Wuchang and Wuhu were clustered into one subgroup. Then the three subgroups were clustered into the third group.Analyzed using Arlequin3.11software, a total of86haplotype was found in all populations. The frequency of haplotype (96/146/160/175/223) was the highest (0.100000). The diversity of haplotype in Fuzhou (FZ) population was the highest (0.5202), while that in Hangzhou (HZ) population was the lowest (0.1867). The number of haplotypes in Nanjing (NJ) population was the highest (23), while that in Hangzhou (HZ) population was the lowest (7). The result suggested that Pudong might be the origin of the populations, then invaded into the southern of China including Hangzhou, Taizhou, Fuzhou, into the northern of China including Lianyungang, and into the western of China including Jiujiang, Wuhu Hankou, Jingdezhen, Nanjing, and Wucang. Nantong and Hongqiao populations might be new invaded populations or the back-invaded populations.