Angiosperm phylogeny: 17 genes, 640 taxa Soltis, Douglas E.; Smith, Stephen A.; Cellinese, Nico ...
American journal of botany,
April 2011, Volume:
98, Issue:
4
Journal Article
Peer reviewed
Open access
Premise of the study. Recent analyses employing up to five genes have provided numerous insights into angiosperm phylogeny, but many relationships have remained unresolved or poorly supported. In the ...hope of improving our understanding of angiosperm phylogeny, we expanded sampling of taxa and genes beyond previous analyses. Methods: We conducted two primary analyses based on 640 species representing 330 families. The first included 25260 aligned base pairs (bp) from 17 genes (representing all three plant genomes, i. e., nucleus, plastid, and mitochondrion). The second included 19846 aligned bp from 13 genes (representing only the nucleus and plastid). Key results: Many important questions of deep-level relationships in the nonmonocot angiosperms have now been resolved with strong support. Amborellaceae, Nymphaeales, and Austrobaileyales are successive sisters to the remaining angiosperms (Mesangiospermae), which are resolved into Chloranthales + Magnoliidae as sister to Monocotyledoneae + Ceratophyllaceae + Eudicotyledoneae. Eudicotyledoneae contains a basal grade subtending Gunneridae. Within Gunneridae, Gunnerales are sister to the remainder (Pentapetalae), which comprises (1) Superrosidae, consisting of Rosidae (including Vitaceae) and Saxifragales; and (2) Superasteridae, comprising Berberidopsidales, Santalales, CaryophyHales, Asteridae, and, based on this study, Dilleniaceae (although other recent analyses disagree with this placement). Within the major subclades of Pentapetalae, most deep-level relationships are resolved with strong support. Conclusions: Our analyses confirm that with large amounts of sequence data, most deep-level relationships within the angiosperms can be resolved. We anticipate that this well-resolved angiosperm tree will be of broad utility for many areas of biology, including physiology, ecology, paleobiology, and genomics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Although agriculture focuses on row crops in the Midwestern US, chestnut (
Castanea
) would be a possible multipurpose agroforestry crop in erodible locations within this region. As ectomycorrhizal ...(ECM) colonization is often crucial for tree establishment and production, we addressed the importance of ECM colonization on chestnut performance by assessing: (1) natural ECM colonization in an established chestnut orchard, and (2) the effect of ECM inoculation on seedling establishment and drought response in a greenhouse. We selected 50 Chinese American hybrid chestnuts trees in a commercial orchard and assessed their level of mycorrhizal colonization in relation to distance from an adjacent forest, the source of inoculum. In the green house, we grew 80 seedlings from this orchard with and without mycorrhizal inoculation. Half were harvested to assess inoculation success and biomass; the remainder were subjected to experimental water stress which was evaluated with chlorophyll fluorescence using Fv/Fm values. In the orchard planted with uninoculated plants, ECM colonization decreased with distance from adjacent oak forest (
P
= 0.015), the putative ECM source, with an average of 29% root tips colonized. ECM inoculation increased seedling aboveground biomass by 16.4% in the greenhouse and generated 1.14 times more, but smaller stomata on leaves. Water stress in ECM inoculated seedlings also recovered faster from an experimental drought having significantly higher Fv/Fm value (
P
= 0.004) than uninoculated seedlings. Our study clearly indicates that ectomycorrhizal colonization can help chestnut trees in their early growth and stress tolerance and should be included into field plantings to minimize dependence on agricultural amendments.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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•Molecular phylogeny of African angraecoid orchids encompassing 80% of genera.•ITS-1, matK and trnL-F regions sequenced from 555 individuals belonging to 284 species.•Angraecoids ...comprise two main clades: African/American group and Indian Ocean group.•Angraecum, Angraecopsis, Diaphananthe and Margelliantha are polyphyletic.•Angraecum includes several other genera of which two need to be described.
Despite significant progress made in recent years toward developing an infrafamilial classification of Orchidaceae, our understanding of relationships among and within tribal and subtribal groups of epidendroid orchids remains incomplete. To reassess generic delimitation among one group of these epidendroids, the African angraecoids, phylogenetic relationships were inferred from DNA sequence data from three regions, ITS, matK, and the trnL-trnF intergenic spacer, obtained from a broadly representative sample of taxa. Parsimony and Bayesian analyses yielded highly resolved trees that are in clear agreement and show significant support for many key clades within subtribe Angraecinae s.l. Angraecoid orchids comprise two well-supported clades: an African/American group and an Indian Ocean group. Molecular results also support many previously proposed relationships among genera, but also reveal some unexpected relationships. The genera Aerangis, Ancistrorhynchus, Bolusiella, Campylocentrum, Cyrtorchis, Dendrophylax, Eurychone, Microcoelia, Nephrangis, Podangis and Solenangis are all shown to be monophyletic, but Angraecopsis, Diaphananthe and Margelliantha are polyphyletic. Diaphananthe forms three well-supported clades, one of which might represent a new genus, and Rhipidoglossum is paraphyletic with respect to Cribbia and Rhaesteria, and also includes taxa currently assigned to Margelliantha. Tridactyle too is paraphyletic as Eggelingia is embedded within it. The large genus Angraecum is confirmed to be polyphyletic and several groups will have to be recognized as separate genera, including sections Dolabrifolia and Hadrangis. The recently segregated genus Pectinariella (previously recognized as A. sect. Pectinaria) is polyphyletic and its Continental African species will have to be removed. Similarly, some of the species recently transferred to Angraecoides that were previously placed in Angraecum sects. Afrangraecum and Conchoglossum will have to be moved and described as a new genus.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Members of tribe Vandeae (Orchidaceae) form a large, pantropical clade of horticulturally important epiphytes. Monopodial leafless members of Vandeae have undergone extreme reduction in habit and ...represent a novel adaptation to the canopy environment in tropical Africa, Asia, and America. To study the evolution of monopodial leaflessness, molecular and structural evidence was used to generate phylogenetic hypotheses for Vandeae. Molecular analyses used sequence data from ITS nrDNA, trnL-F plastid DNA, and matK plastid DNA. Maximum parsimony analyses of these three DNA regions each supported two subtribes within monopodial Vandeae: Aeridinae and a combined Angraecinae + Aerangidinae. Adding structural characters to sequence data resulted in trees with more homoplasy, but gave fewer trees each with more well-supported clades than either data set alone. Two techniques for examining character evolution were compared: (1) mapping vegetative characters onto a molecular topology and (2) tracing vegetative characters onto a combined structural and molecular topology. In both cases, structural synapomorphies supporting monopodial Vandeae were nearly identical. A change in leaf morphology (usually reduced to a nonphotosynthetic scale), monopodial growth habit, and aeration complexes for gas exchange in photosynthetic roots seem to be the most important characters in making the evolutionary transition to leaflessness.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Arbuscular mycorrhizae (AM) are widespread in plant communities and are important mediators of plant community structure. However, patterns of variation among species and linkages with above-ground ...traits have received much less attention. To address this research need, we surveyed plant species from a long-term study of old field succession for AM colonization. Root tissue was collected from five individuals for each of 46 species that represented a range of origins and life forms. Root samples were cleared, stained, and examined to determine the percentage of colonized hyphae area and the number of vesicles and arbuscules. Nonnative species had greater hyphal colonization than native taxa, and the number of vesicles produced in woody species was lower than in the herbaceous species of the system. AM were associated with above-ground traits in both woody and herbaceous taxa, suggesting mycorrhizae integrate with other plant traits to generate resource acquisition strategies. AM decreased as species peaked later in succession for herbaceous species but was not associated in woody species. These results suggest AM may play an important role in species invasion and overall plant functional strategies, but these relationships may vary based on plant life form.
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BFBNIB, DOBA, IZUM, KILJ, NMLJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Plastid DNA sequences have been widely used by systematists for reconstructing plant phylogenies. The utility of any DNA region for phylogenetic analysis is determined by ease of amplification and ...sequencing, confidence of assessment in phylogenetic character alignment, and by variability across broad taxon sampling. Often, a compromise must be made between using relatively highly conserved coding regions or highly variable introns and intergenic spacers. Analyses of a combination of these types of DNA regions yield phylogenetic structure at various levels of a tree (i.e., along the spine and at the tips of the branches). Here, we demonstrate the phylogenetic utility of a heretofore unused portion of a plastid protein-coding gene, hypothetical chloroplast open reading frame 1 (ycf1), in orchids. All portions of ycf1 examined are highly variable, yet alignable across Orchidaceae, and are phylogenetically informative at the level of species. In Orchidaceae, ycf1 is more variable than matK both in total number of parsimony informative characters and in percent variability. The nrITS region is more variable than ycf1, but is more difficult to align. Although we only demonstrate the phylogenetic utility of ycf1 in orchids, it is likely to be similarly useful among other plant taxa.
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BFBNIB, DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NMLJ, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The large angraecoid orchid clade (subtribe Angraecinae
sensu lato) has undergone extensive radiation in the western Indian Ocean, which includes Africa, Madagascar, and a number of Indian Ocean ...islands, such as the Mascarene Archipelago. To investigate systematics and biogeography of these Mascarene orchids, phylogenetic relationships were inferred from four plastid DNA regions,
trnL intron,
trnL-F intergenic spacer,
matK gene, and
rps16 intron. Parsimony and Bayesian analyses provided identical sets of relationships within the subtribe; the large genus
Angraecum as currently circumscribed does not form an exclusive clade.
Bonniera, an endemic genus to Reunion, is shown to be embedded in part of
Angraecum. Evidence from our research supports the main origin of Mascarene Angraecinae from Madagascar, and although there were many independent colonizations, only a few of the lineages radiated within the Mascarene Archipelago.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Background and AimsA significant proportion of orchid species assigned to subtribe Oncidiinae produce floral oil as a food reward that attracts specialized bee pollinators. This oil is produced ...either by glabrous glands (epithelial elaiophores) or by tufts of secretory hairs (trichomal elaiophores). Although the structure of epithelial elaiophores in the Oncidiinae has been well documented, trichomal elaiophores are less common and have not received as much attention. Only trichomal elaiophores occur in the genus Lockhartia, and their distribution and structure are surveyed here for the first time.MethodsFlowers of 16 species of Lockhartia were studied. The location of floral elaiophores was determined histochemically and their anatomical organization and mode of oil secretion was investigated by means of light microscopy, scanning electron microscopy and transmission electron microscopy.Key Results and Conclusions –All species of Lockhartia investigated have trichomal elaiophores on the adaxial surface of the labellum. Histochemical tests revealed the presence of lipoidal substances within the labellar trichomes. However, the degree of oil production and the distribution of trichomes differed between the three major groups of species found within the genus. All trichomes were unicellular and, in some species, of two distinct sizes, the larger being either capitate or apically branched. The trichomal cuticle was lamellate, and often appeared distended due to the subcuticular accumulation of oil. The labellar trichomes of the three species examined using transmission electron microscopy contained dense, intensely staining cytoplasm with apically located vacuoles. Oil-laden secretory vesicles fused with the plasmalemma and discharged their contents. Oil eventually accumulated between the cell wall and cuticle of the trichome and contained electron-transparent profiles or droplets. This condition is considered unique to Lockhartia among those species of elaiophore-bearing Oncidiinae studied to date.
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Laeliinae are one of the most prominent orchid subtribes, with c. 40 genera and nearly 1500 species, and contain a disparate group of taxa with widely varying morphological features. There does not ...appear to be a complex of characters to which one can refer in order to delineate the subtribe as a whole. Thus, it was thought that vegetative anatomy might provide clues to the monophyly of the group. The microscopic structure of the leaves, stems and roots of representatives of most of the genera was studied. It was concluded that the anatomy lacks overall uniformity and that vegetative characters alone are insufficient to assess the relationships amongst the genera. The only nearly consistent anatomical feature was the abaxial row of fibre bundles in the leaves. Thus, anatomically, as well as morphologically, Laeliinae are a mixed bag.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Triphorinae represents a group of three anatomically simple genera, the structural features of which are unspecialized. The anomocytic stomatal pattern occurs in all genera; it predominates in ...Triphora. A foliar hypodermis, sclerenchyma, fibre bundles and stegmata are absent. The mesophyll is homogeneous. The exodermal and endodermal cells in the roots are entirely thin-walled and tilosomes are absent. However, there are anatomical modifications that appear to be unique: root hairs in Monophyllorchis are borne on velamenal buttresses and, in Psilochilus, they arise endogenously. In the root vascular system of Psilochilus, the metaxylem occurs as a circumferential band. The surfaces of stems in Triphora are tuberculate. Mycorrhizae appear to characterize the root cortices of all genera.
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