Phylogenetic Relationship And Genetic Diversity Study Between Rosa Chinensis Var. Spontanea And Rosa Lucidissim

Rosa chinensis var.spontanea and Rosa lucidissima are two orginal wild species of Sect.Chinenses DC in genus Rosa L.described in Flora Reipublicae Popularis Sinicae.They are also the important ancestors of modern roses and medicinal plant resources.However,the descriptions about the morphological classification between these two species are extremely similar and vague,and different specimens of the same collection number in the herbaria are often identified as two different species.At present,the existing micro-morphological studies and the molecular phylogenetic studies can not separate them.Therefore,it is of great significance to understand the relationship between them for the study of the systematic evolution and speciation of Rosa L.,especially that of Sect.Chinenses DC.It is also the precondition for the conservation and utilization of resources.In this study,the populations in specimen records of both species were investigated to understand its distribution and resource status at first.Then,the phenotypic traits of the collected specimens were measured to analyze the phenotypic variation and diversity among and within populations.Thirdly,the systematic relationship between both species was constructed by using phenotypic traits,ITS and two chloroplast DNA fragments to determine whether they were two independent good species or they were exactly one species in fact.Based on the result of phylogentic relationship study,the genetic diversity of the two species or the complex groups composed by them were investigated.The results were as follows:（1）The geographical distribution of Rosa chinensis var.spontanea and Rosa lucidissima was wide,mainly in Sichuan,Chongqing,Guizhou as the distribution center,and also in Gansu,Hubei,Yunnan,Guangxi and Guangdong,with the distribution elevation from 93m to 1573m.However,the populations were very small with only few or several individuals.,and the species subject to high degree of stress.（2）There were significant differences in flower diameter,petal length and width,pedicels,petioles and so on among and within populations.The individuals were not completely clustered according to population or geographical distance based on morphological traits,and individuals from the same population were distributed in different clustering branch with different threshold values.The populations also were not divided into two large branches according to some key morphological traits.Therefore,the traditional classification of Rosa chinensis var.spontanea and Rosa lucidissima might be onespecies.Phenotypic variation in plant type,leaf size and morphology,flower color,glandular hairs in pedicels and twigs among populations or individuals within populations were due to phenotypic plasticity adapting to local environmental.（3）With Rosa rugosa,Rosa woodsii and Rosa glauca as outgroups,the ITS sequence matrix of all individual plants was 697bp in length,and the combined sequence matrix of two chloroplast fragments（petL-psb E and trnS-trn G）was 2451bp.In the NJ tree based on the chloroplast fragment,all the individuals were divided into two large clades.The genetic distance between each two populations was from 0 to9.063,and the NJ tree divided all the populations into two large clades almost similar to that of the individual clustering.The first clade included all the populations in the distribution center and in the northeast,and the second clade included the southwestern populations,which was inconsistent with the distribution description about Rosa.chinensis var.spontanea and Rosa.lucidissima.Combined with the key phenotypic characters of each population,it illustrated that R.chinensis var.spontanea and R.lucidissima in traditional classification were not two independent species,and that they were one species in fact.The intraspecific phenotypic variation was the result of genetic variation and the long-term adaptation to the environment.It is suggested to merge the two species into one and define it as a complex according to the genetic variation within the species.（4）Based on the above results,the genetic diversity study of the total 331individuals in 26 populations detected a total of 24 haplotypes.With a genetic diversity（H_T）of 0.763 and a haplotype polymorphism（H_d）of 0.724,the complex group had a relatively high genetic diversity with a high degree of genetic differentiation(G_st=0.841)among the populations.Thus,the main threats to their survival might be mainly caused by human activities.According to the genetic structure,it is suggested that in situ conservation strategies should be adopted to protect as many populations as possible and to give priority to the protection of populations with higher genetic diversity.