A Study On Morphological Variation And Molecular Phylogenetics Of Epimeidum Sagittatum Complex

Epimedium sagittatum complex belongs to the genus Epimedium of the family Berberidaceae,and is the collective name of E.sagittatum(Sieb.& Zucc.)Maxim.and its relatives in the east,central and southwestern provinces of China,with seven species and four varieties.The morphological similarity among the species of this complex group,the extensive infraspecific variation,and the difficulty of species definition make it urgent to carry out in-depth taxonomic studies to clarify the origin.This could effectively promote the development and utilization of the resource of Epimedium plants,and provide the scientific basis for phylogenetic reconstructions and taxonomic revisions.In this study,we focused on the morphological characters,genetic diversity and phylogenetic relationships of 33 populations of E.sagittatum complex.The main results are as follows:1.The morphological variation of E.sagittatum complex was investigated through the common garden experiment.The results showed that the morphological traits of the E.sagittatum complex from different geographic origins showed significant variation in leaves,flowers and inflorescences.The morphological traits of E.sagittatum complex under common garden cultivation were similar to those of populations in natural habitats.For example,after 4 years of co-gardening,the number of flowers and inflorescence width of populations from western China(GZ,KY)and eastern China(ZJ,FJ)did not change,and these morphological features still didn’t changed after 10 years of co-gardening,indicating that genetic variation had a great influence on the morphological variation of the E.sagittatum complex.2.The genetic diversity and genetics structure of 33 populations of the E.sagittatum complex was investigated using 12 EST-SSR loci.The results showed that the E.sagittatum complex maintained a high degree of genetic differentiation and genetic diversity.Mantel test showed that the genetic distance of the E.sagittatum complex was significantly positively correlated with the geographic distance,which indicated that this complex group was in accord with Isolation by Distance(IBD).An analysis of molecular variance(AMOVA)showed that there was a high degree of genetic variation between the species of Epimedium,and the genetic variation mainly existed among populations.Additionally,genetic structure analysis and UPGMA tree showed that the E.sagittatum complex could be divided into 3 groups.3.The phylogenetic relationships of E.sagittatum complex were analyzed by genotyping-by-sequencing technology.After strict filtering,a total of 84.23 G data volume was obtained,with an average of 1.20 G data volume per sample.A total of47495778 high-quality SNPs were obtained,and the average number of SNPs per individual was 678511.Based on these SNPs,the population phylogenetic tree,population structure and principal component were analyzed.The results showed that there were significant genetic differences in the LT population,YZ05 population and KY population of E.sagittatum.E.borealiguizhouense S.Z.He et Y.K.Ying was more closely related with E.myrianthum Stearn and E.sagittatum.Besides,combined with morphological data,E.multiflorum Ying and E.coactum H.R.Liang et W.M.Yan were reduced to synonyms of E.myrianthum,and E.pudingense S.Z.He,Y.Y.Wang & B.L.Guo was reduced to synonyms of E.sagittatum.