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| 2. |
- Groeninckx, Inge, et al.
(författare)
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Phylogeny of the Herbaceous Tribe Spermacoceae (Rubiaceae) Based on Plastid DNA Data
- 2009
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Ingår i: Annals of Missouri Botanical Garden. - : Missouri Botanical Garden Press. - 0026-6493 .- 2162-4372. ; 96:1, s. 109-132
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Tidskriftsartikel (refereegranskat)abstract
- Abstract In its current circumscription, the herbaceous tribe Spermacoceae s.l. (Rubiaceae, Rubioideae) unites the former tribes Spermacoceae s. str., Manettieae, and the Hedyotis–Oldenlandia group. Within Spermacoceae, and particularly within the Hedyotis–Oldenlandia group, the generic delimitations are problematic. Up until now, molecular studies have focused on specific taxonomic problems within the tribe. This study is the first to address phylogenetic relationships within Spermacoceae from a tribal perspective. Sequences of three plastid markers (atpB-rbcL, rps16, and trnL-trnF) were analyzed separately as well as combined using parsimony and Bayesian approaches. Our results support the expanded tribe Spermacoceae as monophyletic. The former tribe Spermacoceae s. str. forms a monophyletic clade nested within the Hedyotis–Oldenlandia group. Several genera formerly recognized within the Hedyotis–Oldenlandia group are supported as monophyletic (Amphiasma Bremek., Arcytophyllum Willd. ex Schult. & Schult. f., Dentella J. R. Forst. & G. Forst., Kadua Cham. & Schltdl., and Phylohydrax Puff), while others appear to be paraphyletic (e.g., Agathisanthemum Klotzsch), biphyletic (Kohautia Cham. & Schltdl.), or polyphyletic (Hedyotis L. and Oldenlandia L. sensu Bremekamp). Morphological investigations of the taxa are ongoing in order to find support for the many new clades and relationships detected. This study provides a phylogenetic hypothesis with broad sampling across the major lineages of Spermacoceae that can be used to guide future species-level and generic studies
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- Gruber, Christian W, et al.
(författare)
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Distribution and evolution of circular miniproteins in flowering plants
- 2008
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 20:9, s. 2471-2483
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Tidskriftsartikel (refereegranskat)abstract
- Cyclotides are disulfide-rich miniproteins with the unique structural features of a circular backbone and knotted arrangement of three conserved disulfide bonds. Cyclotides have been found only in two plant families: in every analyzed species of the violet family (Violaceae) and in few species of the coffee family (Rubiaceae). In this study, we analyzed >200 Rubiaceae species and confirmed the presence of cyclotides in 22 species. Additionally, we analyzed >140 species in related plant families to Rubiaceae and Violaceae and report the occurrence of cyclotides in the Apocynaceae. We further report new cyclotide sequences that provide insights into the mechanistic basis of cyclotide evolution. On the basis of the phylogeny of cyclotide-bearing plants and the analysis of cyclotide precursor gene sequences, we hypothesize that cyclotide evolution occurred independently in various plant families after the divergence of Asterids and Rosids ( approximately 125 million years ago). This is strongly supported by recent findings on the in planta biosynthesis of cyclotides, which involves the serendipitous recruitment of ubiquitous proteolytic enzymes for cyclization. We further predict that the number of cyclotides within the Rubiaceae may exceed tens of thousands, potentially making cyclotides one of the largest protein families in the plant kingdom.
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- Neupane, Suman, et al.
(författare)
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The Hedyotis-Oldenlandia complex (Rubiaceae: Spermacoceae) in Asia and the Pacific : Phylogeny revisited with new generic delimitations
- 2015
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Ingår i: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 64:2, s. 299-322
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Tidskriftsartikel (refereegranskat)abstract
- Hedyotis and related genera (here called the Hedyotis-Oldenlandia complex) are highly debated groups in the Rubiaceae family with no consensus to date on their generic delimitations. The present study focuses on Asian-Pacific taxa from these groups and aims at resolving taxonomic inconsistencies by describing monophyletic genera within the complex. The generic circumscriptions presented in our study are based on the phylogenetic trees of nuclear (ITS, ETS) and plastid (petD, rps16) sequence data inferred using Bayesian and maximum likelihood methods. Morphological key features of the group such as habit, fruit type, seed form, and pollen type are studied and compared with the phylogeny to characterize the clades. Based on these results, the Asian-Pacific members are placed in 14 monophyletic groups across the Hedyotis-Oldenlandia complex. Of these, we accept and circumscribe 13 monophyletic genera: Debia, Dentella, Dimetia, Edrastima, Exallage, Hedyotis, Involucrella, Kadua, Kohautia, Leptopetalum, Neanotis, Oldenlandia, and Scleromitrion. Two of these, Debia and Involucrella, are here described as new genera.
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