J Syst Evol ›› 2016, Vol. 54 ›› Issue (1): 37-47.DOI: 10.1111/jse.12157

• Research Articles • Previous Articles     Next Articles

Molecular phylogeny of Chinese Rubia (Rubiaceae: Rubieae) inferred from nuclear and plastid DNA sequences

Li-E Yang1,2, Hang Sun1, Friedrich Ehrendorfer3, and Ze-Long Nie4*   

  1. 1Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
    2University of Chinese Academy of Sciences, Beijing 100049, China
    3Department for Systematic and Evolutionary Botany, University of Vienna, Rennweg 14, Austria
    4Key Laboratory of Plant Resources Conservation and Utilization, College of Biology and Environmental Sciences, Jishou University, Jishou, Hunan 416000, China
  • Received:2014-07-20 Published:2015-07-15

Abstract: Rubia L. is the type genus of the coffee family Rubiaceae and the third largest genus in the tribe Rubieae, comprising ca. 80 species restricted to the Old World. China is an important diversity center for Rubia, where approximately half of its species occur. However, its internal phylogenetic relationships are still poorly understood. The objective of the present study is to contribute to the phylogenetic relationships within Rubia, using the nuclear internal transcribed spacer and six plastid markers and focusing on species from China. Twenty-seven species of Rubia were sampled to infer their phylogeny using Maximum parsimony, Maximum likelihood, and Bayesian analyses. The monophyly of Rubia is supported, provided that R. rezniczenkoana Litv. is excluded from Rubia and transferred to Galium as a new combination: G. rezniczenkoanum (Litv.) L. E Yang & Z. L. Nie. Within Rubia, two clades are clearly supported. They correspond to the traditional sect. Rubias.l. (A) and sect. Oligoneura Pojark. (B), and are morphologically mainly separable by their pinnate (A) versus palmate (B) leaf venation. Plesiomorphic features are the pinnate leaf veining in sect. Rubia s.l. and the occurrence of some species with opposite leaves and true stipules in sect. Oligoneura. In sect. Oligoneura one can assume an evolution from species with opposite leaves and true stipules (as in the R. siamensis Craib group) to those with whorls of two leaves and two leaf-like stipules (as in ser. Chinenses and the R. mandersii Collett & Hemsl. group) and finally with whorls of 6 or even more elements (as in ser. Cordifoliae). The correlation between clades recognized by DNA analyses and available differential morphological features is partly only loose, particularly in the group of R. cordifolia with 2×, 4×, and 6× cytotypes. This may be due to rapid evolutionary divergence and/or hybridization and allopolyploidy.

Key words: molecular phylogeny, morphology (leaves, stipules), Rubieae, taxonomy