| Phyllagathis cavaleriei(H.Lév.& Vaniot)Guillaumin and its related species(P.cavaleriei var.tankahkeei(Merr.)C.Y.Wu ex C.Chen,P.cavaleriei var.wilsoniana Guillaumin)of Melastomataceae are endemic to China,which combines ornamental,medicinal and forage uses,and have high landscape value.Predecessors carried out classification studies using morphology and molecular markers.However,due to the limited number of specimens and sampling points,and the limitation of molecular markers,the definition of P.cavaleriei and its related species unclear.In this study,we expanded the range of sampling sites and the number of samples and based on a comprehensive collection of samples of P.cavaleriei and its related species in China,morphology combined with molecular markers(traditional ITS fragments,chloroplast genome and high-quality SNPs sites)were first used to clarify their classification relationship,and further provided scientific theoretical basis for its better development and utilization in gardens and other fields.Results were as follows:(1)The degree of intraspecific variation in leaf morphology: P.cavaleriei var.tankahkeei > P.cavaleriei > P.cavaleriei var.wilsoniana.Among them,the variation coefficient of petiole length was the largest and was not recommended as a classification basis.The quantitative classification of 23 morphological supported that 36 materials were divided into two groups.Group I included all accessions of P.cavaleriei and P.cavaleriei var.tankahkeei;group II included only P.cavaleriei var.wilsoniana.(2)The stomatal of all samples were polocytic type and randomly,distributed only in the lower epidermis.The cells shape and anticlinal walls for them were consistent,with no difference between samples.There was no difference in the indumentum type,cell size,density and length-width ratio of lower epidermal between P.cavaleriei and P.cavaleriei var.tankahkeei,but these characteristics were different between P.cavaleriei var.wilsoniana and P.cavaleriei,P.cavaleriei var.tankahkeei.The former was also covered with multiseriate multicellular,and its lower epidermal cells were the largest,the length-width ratio and the smallest density.Therefore,the above-mentioned leaf epidermal micro-morphological characteristics can be used as the classification basis for P.cavaleriei var.wilsoniana,and P.cavaleriei,P.cavaleriei var.tankahkeei.(3)The phylogenetic tree based on the chloroplast genome which partial topologies were conflicted with nr ITS and SNPs molecular markers.The whole support rate of phylogenetic trees based on the nr ITS were not high,and the phylogenetic tree generated from chloroplast genome and SNPs data were generally better resolved than the nr ITS in terms of relationships both within and among clades.The support rate of the phylogenetic tree based on chloroplast genome and SNPs was significantly higher than nr ITS,the results supported that P.cavaleriei var.wilsoniana should be an independent evolution branch,while P.cavaleriei and P.cavaleriei var.tankahkeei were embedded in each other.Based on morphological and molecular evidences,this study makes a taxonomic treatment of Phyllagathis cavaleriei var.wilsoniana Guillaumin,raises it to a species——Phyllagathis wilsoniana(Guillaumin)W.C.Zhang & D.H.Peng. |
