A Study Of Leontopodium In China Based On Morphology And Molecular Phylogeny

Leontopodium R.Brown belongs to the Gnaphalieae family of the Asteraceae family,and is mainly distributed in the frigid,emperate and subtropics regions of Asia-Europe.It was the second largest genera in the northern hemisphere,the Leontopodium is widely distributed,with many taxa,inter-species delimitation is ambiguous,and overlapping morphological characters.Therefore,the systematic relationship between species has been controversial.Although the taxonomic research of Leontopodium has made advances in morphology and molecules,there are few species of Leontopodium studied in the past,and the applicability of the molecular markers used was limited.In this study,based on the morphology and molecular phylogeny,mainly discussing morphological characteristics,monophyly problem,phylogenetic relationships of Leontopodium,and also discussing the phylogenetic relationships among related genera.The results of this study are as follows:1.Through collation and analysis of Leontopodium literature,a large number of specimen studies and field investigations,37 species(2 varieties)of Leontopodium were confirmed in China,and based on the morphological characteristics,recompilation the retrieval table of Leontopodium in China,and the same time,the morphological characteristics of Leontopodium were supplemented,statistically and analyzed.The main taxonomic traits are:(1)based on leaf base and stem texture: I.the leaf base is not with sheath,and stem texture is herbaceous;II the leaf base is not with sheath,and stem texture is tend to be lignified;III.the leaf base is with sheath,and stem texture is herbaceous;(2)based on the bracts: they can divide into ovate-lanceolate and lanceolate;in regard to the tearing mode,they are divided into three characters: near whole or slightly lacerate and lacerate(fringed,lacerate and deeply lacerate);(3)based on the male flower crown shape: they can divided into Tubulosus,Tubulosus-infundibuliformis and Infundibuliformis.At the same time,the Q-type cluster analysis was carried out by using SPSS to preliminarily study the genetic relationship of all species of Leontopodium.From the morphological characteristics and cluster analysis results,the traditional classification was supported.2.Based on Illumina Hi Seq high-throughput sequencing technique,a total of 38 complete chloroplast genome sequences(one of incomplete)and 46 nuclear gene(ETS,ITS)sequences were from Leontopodium and related species.After a series of biological information analysis,the chloroplast genomes shown a typical quadripartite structure,and in size,structure and genetic composition are similar.The total length is between 151,062 and 153,266 bp.A total of 87 protein coding genes,37 t RNA genes,and 8 r RNA genes were annotated of Leontopodium and related genera,and the GC content are 37.3%.The codon usage of Leontopodium are coincident,and prefer to use A or T bases.The number and type of repeats in the chloroplast genome of Leontopodium are also coincident.The consistency of the chloroplast genome sequence shown Leontopodium chloroplast genomes were highly conservative,and the IR region contraction and expansion analysis also showed IR region was highly conservative.3.Based on the chloroplast genome sequences and nuclear genes(ETS + ITS)sequences of Leontopodium and related species,using the maximum likelihood method(ML)and maximum parsimony method(MP)to construct phylogeny trees.All the results showed that the Leontopodium monophyly was a monophyletic group.In phylogenetic trees based on chloroplast genomes and nuclear genes(ETS+ITS),Leontopodium was mainly divided into two Clade.The first clade is consist of L.forrestianum(Subgen.Paragnaphalium),and the morphological characteristics are the leaves are not with sheath,and stem texture is herbaceous.The other one is composed of two section(section 1 and section 2).The section 1 is consist of Sect.Nobilia,and four species from Sect.Leontopodium;and the morphological characteristics are leaves are not with sheath,and the stems tend to be lignified.The section 2 is consist of Sect.Leontopodium,and two species from Sect.Nobilia;and the morphological characteristics are the leaves are with sheath,and the stem is herbaceous.Therefore,in combination with the morphological characters,clustering analysis and phylogenetic tree all support that Leontopodium be divided into two subgenera.The phylogenetic trees topology structure based on cp DNA and nr DNA is inconsistent may indicate with interspecific hybridization or polyploidy,incomplete lineage sorting or introgression.