Abstract: Dendrobium officinale is a Chinese herbal medicine and mainly cultivated artificially with multiple botanical origins. A total of 22 D. officinale samples were collected from six different localities of China. The chloroplast genes matK and rbcL form 22 samples were amplified using PCR, and the purified PCR products were sequenced. These samples sequences with 33 matK and 30 rbcL sequences of different Dendrobium species were analyzed on sequence features, genetic variation and phylogenetic relationships. The average length of matK sequences were 1 708 bp, and average GC content was 32% with 768 conserved (polymorphic) sites and 871 parsimony informative sites; the average length of matK sequences were 1 332 bp, and average GC content was 42.9%, 802 conserved (polymorphic) sites and 24 parsimony informative sites. In genetic diversity, the haplotypes (H) of matK sequence was 32, values of haplotype polymorphism (Hd) was 0.842, and nucleotide diversity (π) was 0.270 16. For rbcL sequence, H was 10, Hd was 0.664, and π was 0.026 11. The genetic diversity of the populations of D. officinale was very high. In the phylogenetic trees, both gene matK and rbcL presented almost in all samples as a group with the D. officinale and consistent with their geographical distributions. In conclusion, the matK sequence had higher genetic diversity for phylogenetic analysis of Dendrobium. There was obvious regional characteristics in evolution for germplasm resources of D. officinale in six different provinces of China.

Key words: Dendrobium spp., Dendrobium officinale, chloroplast gene, phylogenetic analysis