Phylogenetic relationships of seabuckthorn based on ITS sequences

Sequences of the internal transcribed spacer( ITS) was compared in three seabuckthrons( Hippophae rhamnoides subsp. sinensis,H. tibetana and H. neurocarpa) distributed in Qinghai Province,then the systematic positions of 15 seabuckthron samples were analyzed with Elaeagnaceae angustifolia being outgroup. The results showed that ITS sequences in three seabuckthron species varied in length from 600 to 605 bp. ITS-1,5. 8S and ITS-2 varied from 201 to 203 bp,166 to167 bp and 232 to 236 bp,respectively. The sequence divergence among three seabuckthorn species was also remarkably high. Cluster analysis based on ITS indicated that H. gonicocarpa subsp.litangensis and H. gonicocarpa subsp. goniocarpa were distinct and could be classified as H. gonicocarpa and H. litangensis. H. gyantsensis had the closest genetic relationship with H. salicifolia and the distant relationship with H. rhamnoides subsp. sinensis. The positions of nine subspecies of H. rhamnoides based on morphological classification were different from the results of ITS.