Systematics Of Yunnanopilia And Allied Genera

The genus Yunnanopilia C.Y.Wu & D.Z.Li belongs to Opiliaceae(Benth.)Valeton,mainly distributing in Yunnan and Guangxi provinces of China,North Vietnam and Laos,etc.The family Opiliaceae consists of 12 genera,34 species,mainly distributing in tropical and subtropical regions of the world.Phylogenetic position of Yunnanopilia has been controversial since its publication.In this thesis,the comparative morphology of Yunnanoplia and allied genera were comprehensively studied and analyzed to determine the taxonomic significance of these morphological traits.Phylogenetic relationships of Yunnanopilia and the other genus of Opiliaceae were studied through molecular systematics.Furthermore,the characteristics of chloroplast genome of Yunnanoplia and other 10 genera and phylogenetic relationship of them were further discussed by chloroplast genome sequencing and data analyzing.The results provided scientific basis to understand the phylogeny and evolutionary relationships of genera in Opiliaceae.The main results are as follows: 1.Comparative morphology of Yunnanopilia and allied generaMost genera of Opiliaceae are monotypic genus,the respective species actually almost represented the characteristic of each genus from the view of sampling.Using the methods of field observations,indoor anatomy,paraffin sections,and scanning electron microscopy,the comprehensive comparative morphology to 7 genera in Opiliaceae(Yuannanopilia,Champereia Griffith,Melientha Pierre,Lepionurus Blume,Urobotrya Stapf,Opilia Roxburgh and Cansjera Jussieu)have been studied including ecological habits,leaf epidermis,flower and inflorescence morphology,fruit trait,anatomy of leaf and stem,as well as pollen morphology.The result showed that: the habit of all 7 species are mainly small trees except the 2 species of Opilia amentacea Roxb and Cansjera rheedii J.F.Gmelin which are climbing shrubs.The leaf epidermis of Lepionurus sylvestris Bl.,Urobotrya latisquama(Gagnep.)Hiepko,and Cansjera rheedii have epidermal hair but all the others are smooth.The cystolith,a feuture structure of this family,appears in mesophyll as 4 to 8 cell clusters or paired while in stem as 4 to 8 cell clusters and single.The inflorescences of Champereia manillana(BI.)Merr,Melientha suavis Pierre and Yunnanopilia longistaminea(W.Z.Li)C.Y.Wu & D.Z.Li are panicle,often occured in older branches or main trunk,with female unisexual or gynodioecious flowers,while the inflorescences of Lepionurus sylvestris,Urobotrya latisquama,Opilia amentacea and Cansjera rheedii are axillary raceme or spike inflorescences,occoured in axils of leaves,with bisexual flowers.The color and size of fruits in the genera are also obviously differentiated.The shape and outer wall decoration of pollen grains are obviously different in each genus,providing high support for the classification of different genus.Especially in the 3 allied genera,pollen grain of Champereia manillana is nearly spherical,reticulate-foveolate,but pollen grain of Melientha suavis and Yunnanopilia longistaminea are both long-spherical and reticulate,providing good evidence for their difference and showing that Yunnanopilia longistaminea was more closely related to Melientha suavis than to Champereia manillana.Based on the above comparison of morphological straits,a genus key,including all 7 genera in Southeast Asia,has been also established.As a whole,the controversial Yunnanopilia showed obvious difference in morphological straits with other allied genera,thus the independence of its monotypic genus was confirmed by comparative morphology.2.Phylogenetic placement of Yunnanopilia based on molecular systematicsIn order to determine the systematic position of Yunnanopilia in Opiliaceae,we selected 15 individuals in five populations of Yunnanopilia longistaminea covering its entire geographic range and representative species of other 6 genera of Opiliaceae,also 2 out-groups(Scleropyrum wallichianum Arn.,Santalaceae;Erythropalum scandens Blume,Olacaceae)according to APG IV,based on 2 nrDNA sequences(ITS1-ITS2 and 18 S rDNA)and 4 cpDNA sequences(rbcL,matK,psbA-trnH and trnS-trnG)using maximum likelihood and bayesian inference analysis.The results showed that all genera of Opiliaceae clustered in one main branch,showing the family as a monophyletic group.The relationships of different genera in family were also supported well by the sub branches.Furthermore,all samples of Yunnanopilia longistaminea gathered in one monophyletic clade and it showed Yunnanopilia longistaminea was monophyletic,indicating it is a independent group relative to the 2 allied genera Melientha and Champereia.Yunnanopilia longistaminea and Melientha suavis form as a sister-group,showing they are more closely related than as to Champereia manillana.Therefore,the independence of the genus Yunnanopilia was also confirmed,coinciding with the result of comparative morphology.3.Phylogenetic relationship of Yunnanopilia and allied genera based on chloroplast genomeThe chloroplast genome of 9 genera in Opiliaceae were sequenced by our research and the chloroplast genome data of other 2 genera were cited.The data analysis and phylogenetic relationship rebuilding based on chloroplast genome of 11 genera in Opiliaceae were conducted.The results showed that: the overall length of the chloroplast genome is between 143008bp(Anthobolus filifolius R.Br.)and 147481bp(Melientha suavis).The chloroplast genome of each genus is made up of four parts: large single copy(LSC),small single copy(SSC),and two inverted repeats(IRs).The length of large single copy is 81943-83759 bp,the length of small single copy is 7670-10830 bp,and the length of IR region is 25308-28095 bp.The chloroplast genome of all genera in Opiliaceae are deficient in ndhA-ndhK(11 individuals)protein coding gene.It was supported by chloroplast genome phylogeny that the genus of Anthobolus R.Br.original in Santalaceae should be classified into Opiliaceae,as a basal group of the family and a sister group to other large branches of the remaining 10 genera.At the same time,the tribe of the 3 allied genera,Yunnanopilia,Melientha and Champereia,was also supported by chloroplast genome analysis,clustering in one sub branch.But the genus Yunnanopilia is obviously distinguished from the two allied genera.So its genus status is fully confirmed.According to the result,Opiliaceae could be divided into four tribes: Anthoboleae(Anthobolus);Agonandreae(Agonandra Miers);Champereieae(Champereia,Yunnanopilia,Melientha);Opilieae(Rhopalopilia Pierre,Pentarhopalopilia(Engler)Hiepko,Cansjera,Lepionurus,Urobotrya and Opilia).