Molecular phylogenetics and generic assessment in the tribe Morindeae (Rubiaceae-Rubioideae): how to circumscribe Morinda L. to be monophyletic?

Bergius Foundation, Royal Swedish Academy of Sciences and Botany Department, Stockholm University, SE-10691 Stockholm, Sweden.
Molecular Phylogenetics and Evolution (Impact Factor: 4.07). 05/2009; 52(3):879-86. DOI: 10.1016/j.ympev.2009.04.007
Source: PubMed

ABSTRACT Most of the species of the family Rubiaceae with flowers arranged in head inflorescences are currently classified in three distantly related tribes, Naucleeae (subfamily Cinchonoideae) and Morindeae and Schradereae (subfamily Rubioideae). Within Morindeae the type genus Morinda is traditionally and currently circumscribed based on its head inflorescences and syncarpous fruits (syncarps). These characters are also present in some members of its allied genera, raising doubts about the monophyly of Morinda. We perform Bayesian phylogenetic analyses using combined nrETS/nrITS/trnT-F data for 67 Morindeae taxa and five outgroups from the closely related tribes Mitchelleae and Gaertnereae to rigorously test the monophyly of Morinda as currently delimited and assess the phylogenetic value of head inflorescences and syncarps in Morinda and Morindeae and to evaluate generic relationships and limits in Morindeae. Our analyses demonstrate that head inflorescences and syncarps in Morinda and Morindeae are evolutionarily labile. Morinda is highly paraphyletic, unless the genera Coelospermum, Gynochthodes, Pogonolobus, and Sarcopygme are also included. Morindeae comprises four well-supported and morphologically distinct major lineages: Appunia clade, Morinda clade (including Sarcopygme and the lectotype M. royoc), Coelospermum clade (containing Pogonolobus and Morinda reticulata), and Gynochthodes-Morinda clade. Four possible alternatives for revising generic boundaries are presented to establish monophyletic units. We favor the recognition of the four major lineages of Morindeae as separate genera, because this classification reflects the occurrence of a considerable morphological diversity in the tribe and the phylogenetic and taxonomic distinctness of its newly delimited genera.

  • Source
    Botanical Journal of the Linnean Society 01/2013; 171:395-412. · 2.59 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The evolution of dioecy from heterostyly has been well documented, but detailed studies on this transitional process are rare. Here we report the occurrence of cryptic dioecy in a perennial liana species with stigma-height dimorphism, Morinda parvifolia Bartl. ex DC. (Rubiaceae). Floral morphology, ancillary characters and cross compatibility of long-styled (L-morph) and short-styled (S-morph) were examined. L-morph and S-morph display obvious pistil dimorphisms, with the stigma of S-morph lacking papillae cells. Both floral morphs show similar pollen morphology, although pollen viability is higher in S-morph than in L-morph. S-morph flowers produce viable pollen grains but much reduced stigma and set no fruits, functioning as males; L-morphs, although with viable pollen grains and receptive stigmas, exhibit strong self- and intramorph incompatibility, with self- and intramorph pollen tubes arrested in the stigma lobes and the upper part of style, respectively, resulting in L-morphs functioning only as females. The species thus has physiological androdioecy but functional dioecy. This might be the first case showing the possibility that androdioecy could be a mid-stage in the pathway of dioecy evolving from stigma-height dimorphism.
    Plant Systematics and Evolution 04/2012; 298(4). · 1.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gynochthodes boninensis is a woody climber endemic to the Bonin Islands, Japan. It is characterized by an androdioecious sexual system, which is rare in angiosperms. We conducted a molecular phylogenetic analysis of 29 taxa including 61 samples from the tribe Morindeae to elucidate the geographical origin of G. boninensis by determining its progenitor species. We also investigated evolutionary transitions among different sexual systems within this plant group. The combined ETS, ITS, and trnT-F sequence data showed that G. boninensis formed a monophyletic group, but it did not form a clade with G. umbellata, which was treated as the same species, whereas it formed a clade with G. parvifolia, which is distributed in southeastern Asia. This suggests that G. boninensis evolved independently from G. umbellata, and probably originated from a progenitor native to southeastern Asia. In the clade composed of the three species of G. boninensis, G. parvifolia, and G. umbellata, only G. boninensis is androdioecious, whereas the others are dioecious. Thus, the androdioecious sexual system of G. boninensis may have evolved from dioecy.
    Molecular Phylogenetics and Evolution 04/2013; · 4.07 Impact Factor

Full-text (2 Sources)

Available from
Jun 4, 2014