Abstract: Reported in the present paper is a robust chloroplast matK gene phylogeny of Taxaceae, Cephalotaxaceae and Podocarpaceae represented by 10 species of seven genera, with three species of the Pinaceae as outgroups. The matk length of the 13 species ranges from 1488 bp to 1548 bp, which results from indels, in particular, 1-bp(base pair) insertion near the 3’ end of the gene in some groups. A 27 bp deletion was found at the nucleotide position 213 from the 5’ end of the matk gene of Pseudotaxus chienii. The aligned sequences used in PAUP and MEGA analyses were 1568 bp and 1494 bp respectively. In the matK gene, the rates of variation at the first, second and third codon positions are similar although the mean frequency of synonymous substitution is approximately twice as high as that of nonsynonymous substitution. Branch-and-Bound search found only one most parsimonious tree (tree length = 895, CI = 0.850, RI = 0. 876), in which all clades were strongly supported by bootstrap test. According to the tree, Taxaceae and Cephalotaxaceae are monophyletic groups, and the sister group relationship between the two families was confirmed. Taxus is closely related to Pseudotaxus while Torreya is the sister group of Amentotaxus. In addition, the close relationship between Nageia and Podocarpus was resolved. The present study supports the generic status of Pseudotaxus and Amentotaxus in point of cladistic analysis and genetic distance, but contra-dicts the establishment of the family Nageiaceae.

Key words: Taxaceae, Cephalotaxaceae, Nageia；matK, Molecular systematics