多DNA片段探讨温带竹子的系统发育和网状进化-以箬竹属、铁竹属和赤竹属为主

1. Results and analyses of combined data of eight non-coding loci of the chloroplast genome We produced 8927 bp of sequences from eight non-coding chloroplast regions for a very broad sampling of representatives: 68 species in 18 genera with 2 outgroups. Phylogenetic analyses using maximum parsimony and Bayesian inference supported the temperate bamboos as a monophyletic group. The two major subtribes, Arundinariinae and Shibataeinae based on different inflorescence types were again proved to be polyphyletic. The cladograms suggested that Ferrocalamus was monophyletic, while Indocalamus, Sasa and Gelidocalamus were showed to be polyphyletic. Bashania, Pleioblastus and other 11 genera were proved to be paraphyletic or polyphyletic. Our analyses implied: (1) Using multiple loci chloroplast sequences could still not resolve the in-depth phylogenetic relationships within the temperate bamboo clade. (2) Extensive sampling was indispensable for the temperate bamboo clade, as most genera in the clade have not been proved to be monophyletic. 2. Results and analyses of nrDNA ITS sequences Based on molecular clone and sequencing analyses, a total of 116 distinct clone sequences representing 61 species of 16 genera of the temperate bamboo clade, were obtained and used in the gene genealogy analysis. Our results suggested an incomplete concerted evolution of this locus in some species of the temperate bamboo clade. The evolution pattern and evolution rates of ITS in intergeneric and congeneric species were different. Comparisons with the sequences length, GC-content, base changes, long terminal branch length in gene tree, the clone sequence Sasa shimidzuana_1 was identified as a pseudogene. From the short branch length, and low genetic differentiation, it suggested that the temperate bamboo clade was a group with a rapid evolutionary diversification. Polyploidization and hybridization had played an important role in the species evolution. 3. Results and analyses of a low-copy nuclear GBSSI gene sequences A nuclear low-copy gene phylogeny provided strong evidence for the hybrid origin of nineteen polyploidy species in the temperate bamboo clade. We cloned and sequenced about 1.4 kilobases of GBSSI gene from 71 species representing 17 genera of the temperate bamboo clade. Each of the two (three) loci in one species formed a separate group, which were more closely related to copies in other species than they are to each other. It is indicated that 17 species were allotetraploids, while 2 species were hexaploids. Phylogenetic analyses using maximum parsimony and Bayesian inference again supported temperate bamboos as a monophyletic group. The two subtribes, Arundinariinae and Shibataeinae were again proved to be polyphyletic. The cladograms suggested that Indocalamus, Sasa, Bashania and Gelidocalamus were polyphyletic. Phyllostachys, Pleioblastus, Yushania, Fargesia and Thamonocalamus, as currently defined, were proved to be paraphyletic or polyphyletic. We discussed the molecular evolution of a single-copy gene in an allopolyploid species. It is necessary for finding other low-copy nuclear genes to elucidate the origin and evolution of the temperate bamboo clade. 4. Molecular evolutionary rates in the temperate bamboo clade The combined analyses of eight chloroplast non-coding regions, nrDNA ITS and GBSSI sequences data implied that the temperate bamboo clade had slow molecular evolutionary rates with short branch length and low genetic divergence. The results probably attributed to two main factors. One is related to the very long life history of 15-60 years. Other one is the relatively late time of origin and subsequently radiative speciation.