Phylogeny Of Rehmannia, Triaenophora And Related Families/genera Of Lamiales (Sensu APG Ⅱ)

There are six species in Rehmannia.Except for R.glutinosa distributing from East Asia to Japan,all others are endemic to China.Triaenophora is an endemic genus of China and consists of three species.Historically,different taxonomic systems have conflicting views on whether Triaenophora is an independent natural group or belongs to Rehmannia.The studies of morphology,developmental biology and phytochemistry also have different views on the systematic positions of Rehmannia and Triaenophora.Furthermore,these two genera are seldom sampled in molecular systematic studies,let the systematic positions of Rehmannia and Triaenophora in Lamiales(APGâ…¡)haven't been solved yet.In order to solve these problems,several genes(rbcL,ndhF,rps16,trnL-F)of chloroplast genome and ITS sequences of nuclear genome were sequenced for phylogenetic analyses with maximum parsimony method and maximum likelihood method.The phenetic analysis on 27 related genera was also performed.For the phylogenetic studies of Rehmannia,Triaenophora and related families, rbcL,ndhF and rps16 were chosen,with Exacum(Gentianales)and Capsicum (Solanales)as outgroups.The phylogenetic analyses include 49 representative genera of 18 families in Lamiales.The results show that Rehmannia and Triaenophora constitute a clade with 100%bootstrap percentages which indicate a steady compound group.This group has close relationships with Orobanchaceae,Paulowniaceae and Phrymaceae,with a more evolutional position in Lamiales,and shows obvious distance from Calceolariaceae,Gesneriaceae,Plantaginaceae and Scrophulariaceae. Meanwhile,Gratioleae is a distinct lineage from Plantaginaceae;Lindernia and Torenia constitute a new clade,which is distinct from other lineages of Lamiales,so we support treating them as Linderniaceae.For the phylogenetic studies of Rehmannia,Triaenophora and related genera,we selected 52 representative genera from Orobanchaceae,Paulowniaceae and Phrymaceae,with Calceolaria and Digitalis as outgroups,and performed phylogenetic analyses on rps16,trnL-F and ITS sequences.The results show that:(1) Rehmannia and Triaenophora locate on closely related but independent evolutional clades,and then still constitute a clade with bootstrap percentages higher than 84%. Considering the evidences from macro-morphology,micro-morphology and isoenzyme analysis,Rehmannia and Triaenophora have formed independent natural group respectively,though they only experienced short time differentiation.(2)The Rehmannia-Triaenophora is the sister group of Orobanchaceae.Rehmannia and Triaenophora are nonparasitic plants,which are distinct from the holoparasitic and hemiparasitic species of Orobanchaceae,and also distinct from the nonparasitic Lindenbergia(Orobanchaceae)on the aspects of morphology,chromosome numbers and geographic distribution.So Rehmannia and Triaenophora form an independent compound group which is distinct from Orobanchaceae.(3)Mazus and Lancea should be separated from Phrymaceae.These two genera always constitute a clade with 100%bootstrap percentages in phylogenetic analyses,which is distinct from other lineages of Phrymaceae.For the phenetic analysis on Rehmannia,Triaenophora and related genera,38 morphological characters of 27 representative genera were used on constructing UPGMA phenogram,with Capsicum as a referent.The results confirmed the sister relationship between Rehmannia and Triaenophora.It indicates that the similar morphological characters of these two genera are synapomorphies.The morphological close comparabilities among Rehmannia and Triaenophora,Titanotrichum,Digitalis are not consistent with the results from molecular systamatics,photochemistry and biogeography,which indicate these morphological characters are symplesiomorphies. Rehmannia,Triaenophora and Paulownia have similar genetic background,but bigger morphological differentiation happened during the evolutionary process.It is concluded that there are complicated reticulate evolutions among Rehmannia, Triaenophora,Phrymaceae,Titanotrichum,Digitalis,Paulownia and Orobanchaceae.