Molecular Systematics Of Bamboo Based On Functional Genes MADS1, MOC1 And TB1

Bamboos, which belong to Gramineae (Poaceae), mainly spread in tropical and subtropical area of Asia, Africa, Latin America and even some bamboos spread in temperate area and frigid zone. Asia especially China has the largest number of species and genera of bamboo, and its planting area and production value of bamboos are the highest either. Agricultural and industrial utilization of bamboos occupies an important place in China's economy. For special characteristics of their long flower cycles, bamboo taxonomy and evolution is still in their unrevise state with many confusion and different opinions.We have amplified partial sequences of MADS1, MOC1 (MONOCULM1), and TB1 (teosinte branched 1) genes from 42 bamboo species. Molecular and phylogenetic analyses were performed and the application to bamboo evolution and classification were assessed. The main results were as follows:1. MADS1, MOC1, and TB1 genes which are parts of normally expressed genes in bamboo and may play a role in flower induction and branch formation, were cloned from 42 bamboo species. The comparative analysis of these sequences showed that among the 3 genes examined, MOC1 alleles have the highest G+C contents (up to about 72% totally), while MADS1 and TB1 alleles have relatively low G+C content (about 48% and 64% respectively). A positive correlation was observed between codon bias and G+C contents in different codon position of the synonymous codons. But the correlation may not directely affect bamboo phylogenetic evolution.2. According to molecular phylogenetic analysis of MADS1, MOC1, and TB1 alleles, the bamboo species may be divided to three main monophyletic group, but they are not corresponded to diffuse, unicaespitose and pluricaespitose bamboo. Comparisons of different phylogenies reconstructed based on MADS1, MOC1, and TB1 alleles respectively showed that the phylogeny of MOC1 more strongly supports the traditional bamboo taxonomy than that of MADS1 and TB1. In addition, the comparisons of different regions of MADS1 alleles (MADS1, coding regions, intron VII) found that they are almost the same topology. But no close correlation was observed between molecular phylogenies of different gene and traditional bamboo taxonomy.3. Size polymorphism of MADS1 intron VII has been examined and applied to pursue the evolution of MADS1 alleles and phylogenetic evolution in bamboo. All intron VII of different MADS1 alleles were divided into seven groups according to their size and an evolution of intron VII were inferred based on some assumptions on indel (insert/deletion) in which MADS1 intron VII with a length of 500bp were considered to be the original type. It was suggested that informations of intron size is useful for bamboo phylogenetic evolution and taxonomy.4. On the basis of the results obtained in the present study, the opinion on bamboo evolution were proposed: (1) Bamboos are monophyletic group, (2) Unicaespitose bamboo are not the original bamboo group, (3) Bamboos of genus Arundinaria are multiphyletic group, and (4) Bamboos of genus Phyllostachys are multiphyletic group.5. Furthermore, some ideas on the revision of bamboo taxanomy were proposed: (1) The classification of bamboo should be based on rhizomatous characteristics with more detailed examinations, (2) Information of molecular evolutionary and culm can be used partially in the revision of genus Arundinaria, and (3) Mathematical methods should be utilized in bamboo classification towards rhizomatous characteristics, culm types and branch number.