Phylogenetic Studies Of Yellow Camellias In China Based On NrITS Sequence And DdRAD-seq Data

Camellia(Theaceae)species with yellow flowers,known as yellow camellias,are concentrated in southwest Guangxi and north Vietnam,with only a few reaching Guizhou and Yunnan Province.For the number of species of yellow camellias distributed in China,there are sixteen species and two varietas in Flora reipublicae popularis sinicae(Tomus49(3)),and twelve species and four varietas in Flora of China(Volume 12).There are inconsistencies in the treatment of yellow camellias by the two classification systems.Yellow camellias have yellow petals,which leaves and flowers are rich in a large number of flavonoids and other active substances.Yellow camellias are valuable ornamental plants and Medicinal value.Owing to the strong disturbance of human economic activities,the wild population has been seriously destroyed,and the number of Yellow camellias has been sharply reduced.All Yellow camellia species were categorized as threatened species.Correctly classification of species is the key to reasonable conservation of species.Therefore,it is necessary to further study the phylogenetic relationship of yellow camellias to provide insight into the classification and conservation of yellow camellia species.In this study,we used the nuclear ribosomal internal transcribed spacer(nrITS)sequence and ddRAD-seq data to reveal the phylogenetic relationships about yellow camellias in China.Conclusions are the following:(1)In this study,the aligned nrITS region comprised 713 bp,of which 180 were variable sites and 118 were parsimony informative.The maximum likelihood tree(ML)and Bayesian tree(BI)are constructed with yellow camellia species based on the nrITS sequence.In this study,5552561 SNPs sites were obtained.Based on the ddRAD-seq data,the total 59 yellow camellias samples of reads ranged from 11627342 reads to 112031046 reads.According to the nrITS sequence and ddRAD-seq data,we can have a clear understanding of the phylogenetic relationship of yellow camellias in China.Phylogenomic analyses of yellow camellias based on ddRAD-seq were superior to Sanger sequencing-based approaches and most of the interspecific relationships among yellow camellias have been effectively resolved.(2)Analysis of the phylogenetic relationships among yellow camellias,and the results indicate that C.nitidissima var.macrocarpa has a distant relationship with C.nitidissima,the classification of these two species is not reasonable,C.nitidissima var.macrocarpa as an independent species;C.tunghinensis is highly divergent from C.limonia,C.tunghinensis is a distinctive species;C.pingguoensis var.terminalis is highly divergent from C.pingguoensis,C.pingguoensis var.terminalis is a distinctive species;C.micrantha is closely related to C.chrysanthoides and probably conspecific;C.achrysantha should be a distinctive species;C.multipetala,C.quinqueloculosa and C.longgangensis var.patens are closely related and probably conspecific;C.chuongtsoensis and C.perpetua are closely related and probably conspecific;C.huana and C.tianeensis are closed related and probably conspecific;C.flavida has a distant relationship with C.longgangensis,C.longgangensis var.grandis,C.ptilosperma and C.longruiensis,these species reduced as synonyms of C.flavida are unreasonable;C.wumingensis should be a distinctive species.