Molecular Systematic Study On Microtropis (Celastraceae) In China

In this paper,20 populations from 17 species of the Microtropis plants collected from the tropical and subtropical areas of China were investigated using a molecular phylogenic study.Based on the Sequences informations of trnL intron and trnL-trnF spacer,rpl32-trnL(UAG) regions from cpDNA,and ITS regions form nrDNA form the research materials and GenBank,the molecular phylograms of Microtropis were constructed with different methods.Through an analysis on the phylograms constructed with different menthods based on both cpDNA and nrDNA combined with the achievement of Taxonomic study,the phylogeny of genus Microtropis was discussed.The main conclusions are as the follows:1 Microtropis Wall.ex Meissn.is a monophyletic group.1 Microtropis wui Y Y.M.Shui et W.H.Chen with the Tropical Rain Forest characters is the ancient group of Microtropis Wall.ex Meissn.The characters may be the ancient characters of Microtropis.The Genus Microtropis may have an origin of tropical.Though later than Genus Euonymus Linn.on the divergence time,Microtropis is still considered as an ancient taxonomic group.2 Genus Quetzalia was homologous to Microtropis,and was divergened from the anciet group of Microtropis,which refers to reallocate the Genus Quetzalia to the Genus Microtropis.The floristic geographical element of Microtropis should be considered to be Tropical Asia-Tropical America disjunction.However,the Microtropis species in America was supported to be an indepanded evolution branch for a geographic isolationoccur in the early geochron.3 The Hot Spots of Microtropis were appeared both in South Yunnan of China and Borneo Island of Malay Archipelago.The india-eurasia collision is supposed to be the cause of hot spots. The origin centre of Microtropis is supposed to be on the Indo-China Peninsula.4 The Microtropis can be treated to be two Taxonomic Groups based on the form of Inflorescence,one of which is the group of dichasium,and the other is the group of racemiform cyme.The form of fasciculate cyme includes both racemiform cyme type and dichasium type.The phylogeny status of fasciculate cyme is suggest to have a further study.5 The origin and divergence center of East-Asia Microtropis is Daweishan Mountain in Southeast Yunnan.It is supposed that,there lived both some of the speices of evolutionary offset and some ancient speices in Daweishan Mountain of Pingbian.6 The complex of Microtropis japonica s.1.was mainly located from Yunnan-Guizhou Plateau to Japan archipelago.There are continuous variations in M.japonica s.l..Though some species can be distinguished with some stable characters,the complex is hard to search out a proper taxonomic character to confirm the Taxonomic status of M.japonica s.l..The result of molecular phylogenic study shows a complex origin of M.japonica s.l.,which refers to comprise some close relative species.The phylogeny and taxonomy study on this complex seemed to be more difficult.