Origin And Phylogenetic Relationship Of Invasive Solidago Canadensis L.

Solidago canadensis L. is a perennial herb plant belongs to Solidago genus in Asteraceae family with sexual and asexual reproduction. S. canadensis is native to the North America and was introduced into China in 1935 as an ornamental plant and then spreaded into the field. S. canadensis casued a huge damage to the ecological environments and agriculture in China and caused enormous economic loss. S. canadensis hase been included in the list of important exotic harmful plants in China. It is urgent to explore the origin and sprea pathway of S.canadensis. In this thesis, using chloroplast simple sequence repeats(cp SSR) and the intergenic spacer sequences of chloroplast DNA, we analyzed the genetic diversity of S. canadensis populations, predicted the origin of S. canaensis in China. The role of ploidy on the phylogenetic relationships of S. canadensis populations were analyzed. The results could provide basic theory for the management and control of S.canadensis.The ploidy level of all the individuals of S. canadensis(835 plants in total) were determined using flow cytometry. In the native range of S. canadensis, there are diploid, tetraploid and hexaploid. But in China, only hexaploid plants were detected.Meanwhile in Holland, there was diploid plants. Although there is no direct relationship between the invasiveness an polyploidization, polyploidization might play important role in the success of the invasion of S. canadensis.The genetic diversity of the thirty-two populations of S. canadensis which from native and invasion region were analyzed using cp SSR molecular maker. The results showed that Nei’s gene index(h) was 1.7585 and Shannon informative index(I) was 0.7497, which indicated that the genetic diversity of S. canadensis populations was relative high. The clustering analysis based on UPGMA method showed that thirty-two populations could be divided into Amecrian and China groups. It suggested that Hongqiao was the origin of Solidago canadensis L in China, which was introduced from New York. AMOVA anlysis indicated that the genetic differentiation coefficient(Gst) was 0.3335. 72.17% of the genetic variation existed within populations, while only 27.83% existed among populations. The gene flow(Nm)estimatedd from Gst was 0.9992, which indicated that the gene flow was relatively high among S. canadensis populations.Based on the chloroplast DNA(cp DNA) psb A-trn H and Trn L-F intergenic spacer sequences of 396 individuals from 34 S. canadensis populations, thirty haplotypes were found. According to the minimum spanning network(MSN), the most largest haplotypes shared by all populations was H1. These results indicated that both American and China populations of S. canadensis originated from one ancestor.