Development Of Single-copy Nuclear Gene Markers And Phylogeny Research Of Section Quercus In China

The phylogenetic relationships and speciation processes have always been the focus of evolutionary biology research.Phylogenetic relationship reconstruction can clearly show the phylogenetic relationship between species,and the study of speciation process can explain the evolution of species in nature.The development of sequencing technology,computer science and bioinformatics software,has bring new vitality into phylogenetic analysis.Species of Quercus have extensive interspecies hybrids,which have attracted the attention of plant taxonomists.However,there are few studies on the dilemitation and interspecies development of Quercus.In this paper,based on the transcriptome of Quercus mongolica and Q.robur,we devoloped 19 homologous single copy nuclear gene sequences(SCNGs)of section Quercus.Five chloroplast loci were used to investigate the sharing of chloroplast DNA variation of section Quercus in China,and the limitations of chloroplast sequence variation in the dilemitation of species of section Quercus was discussed.Finally,using the data of 19 SCNGs,Species dilemitation of the section Quercus distributed in China and Japan were studied.Besides,phylogenetic relationship of the section Quercus distributed in China was reconstructed.The main findings are as follows:1)The 19 SCNGs were developed using the transcriptome of Quercus mongolica and Q.robur.The DNA samples of some species of section Quercus,section Cerris and section Lobatae were amplified by the selected primers.It was found that these markers could be widely used in Quercus,and these single-copy nuclear gene markers could well dilemit two closely related species of Chineses white oak,Q.mongolica and Q.liaotungensis,indicating that these single-copy gene are very effective in the dilemitation of species in Quercus.2)Early studies on interspecific hybridization and chloroplast DNA variation of these species are very limited.The analysis of the populations of the section Quercus indicated that the chloroplast variation did not have clear boundary of the species but was consistent with the geographical position.The chloroplast variation was shared with the same species in the oak group and was not suitable for species dilemitation and phylogeny research.3)In this study,19 SCNGs were used to study the species dilemitation and phylogeny of the species from section Quercus.The results of Structure analysis showed that K=9 was the best clustering model,and these SCNGs can be well dilemited species of section Quercus well.The results of phylogenetic analysis showed that the species of the Chinese white oak section was divided into two branches with a main line of north and south,with a strong support of 100%.The posterior probability of the remaining nodes was not high,except that the posterior probability of divergence node of Q.serrarta was 0.91,presumably due to introgression or shared ancestral polymorphism.