Publications by authors named "Gwilym P Lewis"

30 Publications

  • Page 1 of 1

Botanical Monography in the Anthropocene.

Trends Plant Sci 2021 05 9;26(5):433-441. Epub 2021 Feb 9.

Royal Botanic Gardens, Kew, TW9 3AE, UK; Gothenburg Global Biodiversity Centre, Department of Biological and Environmental Sciences, University of Gothenburg, 41319 Gothenburg, Sweden; Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK. Electronic address:

Unprecedented changes in the Earth's biota are prompting urgent efforts to describe and conserve plant diversity. For centuries, botanical monographs - comprehensive systematic treatments of a family or genus - have been the gold standard for disseminating scientific information to accelerate research. The lack of a monograph compounds the risk that undiscovered species become extinct before they can be studied and conserved. Progress towards estimating the Tree of Life and digital information resources now bring even the most ambitious monographs within reach. Here, we recommend best practices to complete monographs urgently, especially for tropical plant groups under imminent threat or with expected socioeconomic benefits. We also highlight the renewed relevance and potential impact of monographies for the understanding, sustainable use, and conservation of biodiversity.
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http://dx.doi.org/10.1016/j.tplants.2020.12.018DOI Listing
May 2021

Hybrid capture of 964 nuclear genes resolves evolutionary relationships in the mimosoid legumes and reveals the polytomous origins of a large pantropical radiation.

Am J Bot 2020 12 30;107(12):1710-1735. Epub 2020 Nov 30.

Department of Systematic and Evolutionary Botany, University of Zurich, Zollikerstrasse 107, Zurich, CH-8008, Switzerland.

Premise: Targeted enrichment methods facilitate sequencing of hundreds of nuclear loci to enhance phylogenetic resolution and elucidate why some parts of the "tree of life" are difficult (if not impossible) to resolve. The mimosoid legumes are a prominent pantropical clade of ~3300 species of woody angiosperms for which previous phylogenies have shown extensive lack of resolution, especially among the species-rich and taxonomically challenging ingoids.

Methods: We generated transcriptomes to select low-copy nuclear genes, enrich these via hybrid capture for representative species of most mimosoid genera, and analyze the resulting data using de novo assembly and various phylogenomic tools for species tree inference. We also evaluate gene tree support and conflict for key internodes and use phylogenetic network analysis to investigate phylogenetic signal across the ingoids.

Results: Our selection of 964 nuclear genes greatly improves phylogenetic resolution across the mimosoid phylogeny and shows that the ingoid clade can be resolved into several well-supported clades. However, nearly all loci show lack of phylogenetic signal for some of the deeper internodes within the ingoids.

Conclusions: Lack of resolution in the ingoid clade is most likely the result of hyperfast diversification, potentially causing a hard polytomy of six or seven lineages. The gene set for targeted sequencing presented here offers great potential to further enhance the phylogeny of mimosoids and the wider Caesalpinioideae with denser taxon sampling, to provide a framework for taxonomic reclassification, and to study the ingoid radiation.
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http://dx.doi.org/10.1002/ajb2.1568DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7839790PMC
December 2020

How diverse is heterochromatin in the Caesalpinia group? Cytogenomic characterization of Erythrostemon hughesii Gagnon & G.P. Lewis (Leguminosae: Caesalpinioideae).

Planta 2020 Sep 12;252(4):49. Epub 2020 Sep 12.

Laboratory of Plant Cytogenetics and Evolution, Department of Botany, Federal University of Pernambuco, Rua Nelson Chaves S/N, Cidade Universitaria, Recife, PE, 50670-420, Brazil.

Main Conclusion: Cytogenomic characterization of Erythrostemon hughesii reveals a heterogeneity of repeats in its subtelomeric heterochromatin. Comparative analyses with other Caesalpinia group species reveal a significant reduction in the abundance of Ty3-gypsy/Chromovirus Tekay retrotransposons during its evolution. In numerically stable karyotypes, repetitive DNA variability is one of the main causes of genome and chromosome variation and evolution. Species from the Caesalpinia group (Leguminosae) are karyotypically characterized by 2n = 24, with small chromosomes and highly variable CMA heterochromatin banding patterns that correlate with environmental variables. Erythrostemon hughesii differs from other species of the group examined to date for having subtelomeric CMA bands; this contrasts with most species in the group which have proximal bands. Here we analyse the repeatome of E. hughesii using genome skimming and chromosomal mapping approaches to characterize the identity of the most abundant repetitive elements and their physical location. The repetitive fraction of E. hughesii comprises 28.73% of the genome. The most abundant elements were retrotransposons (RT) with long terminal repeats (LTR-RT; 9.76%) and satellite DNAs (7.83%). Within the LTR-RTs, the most abundant lineages were: Ty1/copia-Ale (1%), Ty3/gypsy CRM (0.88%) and Ty3/gypsy Athila (0.75%). Using fluorescent in situ hybridization four satellite DNAs and several LTR-RT elements were shown to be present in most subtelomeric CMA bands. These results highlight how the repeatome in E. hughesii, a species from Oaxaca state in Mexico, is clearly distinct from Northeast Brazilian species of the Caesalpinia group, mainly due to its high diversity of repeats in its subtelomeric heterochromatic bands and low amount of LTR-RT Ty3/gypsy-Tekay elements. Comparative sequence analysis of Tekay elements from different species is congruent with a clade-specific origin of this LTR-RT after the divergence of the Caesalpinia group. We hypothesize that repeat-rich heterochromatin may play a role in leading to faster genomic divergence between individuals, increasing speciation and diversification.
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http://dx.doi.org/10.1007/s00425-020-03453-8DOI Listing
September 2020

New Guinea has the world's richest island flora.

Nature 2020 08 5;584(7822):579-583. Epub 2020 Aug 5.

The Papua New Guinea University of Technology, Lae, Papua New Guinea.

New Guinea is the world's largest tropical island and has fascinated naturalists for centuries. Home to some of the best-preserved ecosystems on the planet and to intact ecological gradients-from mangroves to tropical alpine grasslands-that are unmatched in the Asia-Pacific region, it is a globally recognized centre of biological and cultural diversity. So far, however, there has been no attempt to critically catalogue the entire vascular plant diversity of New Guinea. Here we present the first, to our knowledge, expert-verified checklist of the vascular plants of mainland New Guinea and surrounding islands. Our publicly available checklist includes 13,634 species (68% endemic), 1,742 genera and 264 families-suggesting that New Guinea is the most floristically diverse island in the world. Expert knowledge is essential for building checklists in the digital era: reliance on online taxonomic resources alone would have inflated species counts by 22%. Species discovery shows no sign of levelling off, and we discuss steps to accelerate botanical research in the 'Last Unknown'.
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http://dx.doi.org/10.1038/s41586-020-2549-5DOI Listing
August 2020

Evolutionary diversity in tropical tree communities peaks at intermediate precipitation.

Sci Rep 2020 01 24;10(1):1188. Epub 2020 Jan 24.

Royal Botanic Garden Edinburgh, Edinburgh, EH3 5LR, UK.

Global patterns of species and evolutionary diversity in plants are primarily determined by a temperature gradient, but precipitation gradients may be more important within the tropics, where plant species richness is positively associated with the amount of rainfall. The impact of precipitation on the distribution of evolutionary diversity, however, is largely unexplored. Here we detail how evolutionary diversity varies along precipitation gradients by bringing together a comprehensive database on the composition of angiosperm tree communities across lowland tropical South America (2,025 inventories from wet to arid biomes), and a new, large-scale phylogenetic hypothesis for the genera that occur in these ecosystems. We find a marked reduction in the evolutionary diversity of communities at low precipitation. However, unlike species richness, evolutionary diversity does not continually increase with rainfall. Rather, our results show that the greatest evolutionary diversity is found in intermediate precipitation regimes, and that there is a decline in evolutionary diversity above 1,490 mm of mean annual rainfall. If conservation is to prioritise evolutionary diversity, areas of intermediate precipitation that are found in the South American 'arc of deforestation', but which have been neglected in the design of protected area networks in the tropics, merit increased conservation attention.
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http://dx.doi.org/10.1038/s41598-019-55621-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6981197PMC
January 2020

Evolutionary convergence or homology? Comparative cytogenomics of Caesalpinia group species (Leguminosae) reveals diversification in the pericentromeric heterochromatic composition.

Planta 2019 Dec 6;250(6):2173-2186. Epub 2019 Nov 6.

Laboratory of Plant Cytogenetics and Evolution, Department of Botany, Federal University of Pernambuco, Rua Nelson Chaves S/N, Cidade Universitária, Recife, PE, 50670-420, Brazil.

Main Conclusion: We demonstrated by cytogenomic analysis that the proximal heterochromatin of the Northeast Brazilian species of Caesalpinia group is enriched with phylogenetically conserved Ty3/Gypsy-Tekay RT, but diverge in the presence of Ty3/Gypsy-Athila RT and satDNA. The Caesalpinia Group includes 225 species and 27 monophyletic genera of which four occur in Northeastern Brazil: Erythrostemon (1 sp.), Cenostigma (7 spp.), Libidibia (1 sp.), and Paubrasilia (1 sp.). The last three genera are placed in different clades in the Caesalpinia Group phylogeny, and yet they are characterized by having a numerically stable karyotype 2n = 24 (16 M+8A) and GC-rich heterochromatic bands (chromomycin A positive/CMA bands) in the proximal chromosome regions. To characterize the composition of their heterochromatin and test for the homology of these chromosomal regions, genomic DNA was extracted from Cenostigma microphyllum, Libidibia ferrea, and Paubrasilia echinata, and sequenced at low coverage using the Illumina platform. The genomic repetitive fractions were characterized using a Galaxy/RepeatExplorer-Elixir platform. The most abundant elements of each genome were chromosomally located by fluorescent in situ hybridization (FISH) and compared to the CMA heterochromatin distribution. The repetitive fraction of the genomes of C. microphyllum, L. ferrea, and P. echinata were estimated to be 41.70%, 38.44%, and 72.51%, respectively. Ty3/Gypsy retrotransposons (RT), specifically the Tekay lineage, were the most abundant repeats in each of the three genomes. FISH mapping revealed species-specific patterns for the Tekay elements in the proximal regions of the chromosomes, co-localized with CMA bands. Other species-specific patterns were observed, e.g., for the Ty3/Gypsy RT Athila elements which were found in all the proximal heterochromatin of L. ferrea or restricted to the acrocentric chromosomes of C. microphyllum. This Athila labeling co-localized with satellite DNAs (satDNAs). Although the Caesalpinia Group diverged around 55 Mya, our results suggest an ancestral colonization of Tekay RT in the proximal heterochromatin. Thus, the present-day composition of the pericentromeric heterochromatin in these Northeast Brazilian species is a combination of the maintenance of an ancestral Tekay distribution with a species-specific accumulation of other repeats.
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http://dx.doi.org/10.1007/s00425-019-03287-zDOI Listing
December 2019

Global Succulent Biome phylogenetic conservatism across the pantropical Caesalpinia Group (Leguminosae).

New Phytol 2019 06 14;222(4):1994-2008. Epub 2019 Jan 14.

Department of Systematic & Evolutionary Botany, University of Zurich, Zollikerstrasse 107, 8008, Zurich, Switzerland.

The extent to which phylogenetic biome conservatism vs biome shifting determines global patterns of biodiversity remains poorly understood. To address this question, we investigated the biogeography and trajectories of biome and growth form evolution across the Caesalpinia Group (Leguminosae), a clade of 225 species of trees, shrubs and lianas distributed across the Rainforest, Succulent, Temperate and Savanna Biomes. We focused especially on the little-known Succulent Biome, an assemblage of succulent-rich, grass-poor, seasonally dry tropical vegetation distributed disjunctly across the Neotropics, Africa, Arabia and Madagascar. We reconstructed a time-calibrated phylogeny, assembled species occurrence data and assigned species to areas, biomes and growth forms. These data are used to estimate the frequency of transcontinental disjunctions, biome shifts and evolutionary transitions between growth forms and test for phylogenetic biome conservatism and correlated evolution of growth forms and biome shifts. We uncovered a pattern of strong phylogenetic Succulent Biome conservatism. We showed that transcontinental disjunctions confined within the Succulent Biome are frequent and that biome shifts to the Savanna, Rainforest and Temperate Biomes are infrequent and closely associated with shifts in plant growth forms. Our results suggest that the Succulent Biome comprises an ecologically constrained evolutionary arena spanning large geographical disjunctions across the tropics.
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http://dx.doi.org/10.1111/nph.15633DOI Listing
June 2019

A phylogenetic framework of the legume genus Aeschynomene for comparative genetic analysis of the Nod-dependent and Nod-independent symbioses.

BMC Plant Biol 2018 Dec 5;18(1):333. Epub 2018 Dec 5.

IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR LSTM, Campus International de Baillarguet, 34398, Montpellier, France.

Background: Among semi-aquatic species of the legume genus Aeschynomene, some have the property of being nodulated by photosynthetic Bradyrhizobium lacking the nodABC genes necessary for the synthesis of Nod factors. Knowledge of the specificities underlying this Nod-independent symbiosis has been gained from the model legume Aeschynomene evenia but our understanding remains limited due to the lack of comparative genetics with related taxa using a Nod factor-dependent process. To fill this gap, we combined different approaches to perform a thorough comparative analysis in the genus Aeschynomene.

Results: This study significantly broadened previous taxon sampling, including in allied genera, in order to construct a comprehensive phylogeny. In the phylogenetic tree, five main lineages were delineated, including a novel lineage, the Nod-independent clade and another one containing a polytomy that comprised several Aeschynomene groups and all the allied genera. This phylogeny was matched with data on chromosome number, genome size and low-copy nuclear gene sequences to reveal the diploid species and a polytomy containing mostly polyploid taxa. For these taxa, a single allopolyploid origin was inferred and the putative parental lineages were identified. Finally, nodulation tests with different Bradyrhizobium strains revealed new nodulation behaviours and the diploid species outside of the Nod-independent clade were compared for their experimental tractability and genetic diversity.

Conclusions: The extended knowledge of the genetics and biology of the different lineages sheds new light of the evolutionary history of the genus Aeschynomene and they provide a solid framework to exploit efficiently the diversity encountered in Aeschynomene legumes. Notably, our backbone tree contains all the species that are diploid and it clarifies the genetic relationships between the Nod-independent clade and the Nod-dependent lineages. This study enabled the identification of A. americana and A. patula as the most suitable species to undertake a comparative genetic study of the Nod-independent and Nod-dependent symbioses.
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http://dx.doi.org/10.1186/s12870-018-1567-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6282307PMC
December 2018

A new phylogeny-based tribal classification of subfamily Detarioideae, an early branching clade of florally diverse tropical arborescent legumes.

Sci Rep 2018 05 2;8(1):6884. Epub 2018 May 2.

Institut de recherche en biologie végétale and Département de Sciences biologiques, Université de Montréal, 4101 Sherbrooke est, Montréal, H1X 2B2, Canada.

Detarioideae (81 genera, c. 760 species) is one of the six Leguminosae subfamilies recently reinstated by the Legume Phylogeny Working Group. This subfamily displays high morphological variability and is one of the early branching clades in the evolution of legumes. Using previously published and newly generated sequences from four loci (matK-trnK, rpL16, trnG-trnG2G and ITS), we develop a new densely sampled phylogeny to assess generic relationships and tribal delimitations within Detarioideae. The ITS phylogenetic trees are poorly resolved, but the plastid data recover several strongly supported clades, which also are supported in a concatenated plastid + ITS sequence analysis. We propose a new phylogeny-based tribal classification for Detarioideae that includes six tribes: re-circumscribed Detarieae and Amherstieae, and the four new tribes Afzelieae, Barnebydendreae, Saraceae and Schotieae. An identification key and descriptions for each of the tribes are also provided.
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http://dx.doi.org/10.1038/s41598-018-24687-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5932001PMC
May 2018

Naturally occurring variations in the nod-independent model legume Aeschynomene evenia and relatives: a resource for nodulation genetics.

BMC Plant Biol 2018 Apr 3;18(1):54. Epub 2018 Apr 3.

IRD, Laboratoire des Symbioses Tropicales et Méditerranéennes, UMR LSTM, Campus International de Baillarguet, F-34398, Montpellier, France.

Background: Among semi-aquatic species of the legume genus Aeschynomene, some have the unique property of being root and stem-nodulated by photosynthetic Bradyrhizobium lacking the nodABC genes necessary for the production of Nod factors. These species provide an excellent biological system with which to explore the evolution of nodulation in legumes. Among them, Aeschynomene evenia has emerged as a model legume to undertake the genetic dissection of the so-called Nod-independent symbiosis. In addition to the genetic analysis of nodulation on a reference line, natural variation in a germplasm collection could also be surveyed to uncover genetic determinants of nodulation. To this aim, we investigated the patterns of genetic diversity in a collection of 226 Nod-independent Aeschynomene accessions.

Results: A combination of phylogenetic analyses, comprising ITS and low-copy nuclear genes, along with cytogenetic experiments and artificial hybridizations revealed the richness of the Nod-independent Aeschynomene group with the identification of 13 diploid and 6 polyploid well-differentiated taxa. A set of 54 SSRs was used to further delineate taxon boundaries and to identify different genotypes. Patterns of microsatellite diversity also illuminated the genetic basis of the Aeschynomene taxa that were all found to be predominantly autogamous and with a predicted simple disomic inheritance, two attributes favorable for genetics. In addition, taxa displaying a pronounced genetic diversity, notably A. evenia, A. indica and A. sensitiva, were characterized by a clear geographically-based genetic structure and variations in root and stem nodulation.

Conclusion: A well-characterized germplasm collection now exists as a major genetic resource to thoroughly explore the natural variation of nodulation in response to different bradyrhizobial strains. Symbiotic polymorphisms are expected to be found notably in the induction of nodulation, in nitrogen fixation and also in stem nodulation. Subsequent genetic analysis and locus mapping will pave the way for the identification of the underlying genes through forward or reverse genetics. Such discoveries will significantly contribute to our understanding of the molecular mechanisms underpinning how some Aeschynomene species can be efficiently nodulated in a Nod-independent fashion.
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http://dx.doi.org/10.1186/s12870-018-1260-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5883870PMC
April 2018

A new generic system for the pantropical Caesalpinia group (Leguminosae).

PhytoKeys 2016 12(71):1-160. Epub 2016 Oct 12.

Comparative Plant and Fungal Biology Department, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, United Kingdom.

The Caesalpinia group is a large pantropical clade of ca. 205 species in subfamily Caesalpinioideae (Leguminosae) in which generic delimitation has been in a state of considerable flux. Here we present new phylogenetic analyses based on five plastid and one nuclear ribosomal marker, with dense taxon sampling including 172 (84%) of the species and representatives of all previously described genera in the Caesalpinia group. These analyses show that the current classification of the Caesalpinia group into 21 genera needs to be revised. Several genera (, , and sensu Lewis, 2005) are non-monophyletic and several previously unclassified Asian species segregate into clades that merit recognition at generic rank. In addition, the near-completeness of our taxon sampling identifies three species that do not belong in any of the main clades and these are recognised as new monospecific genera. A new generic classification of the Caesalpinia group is presented including a key for the identification of genera, full generic descriptions, illustrations (drawings and photo plates of all genera), and (for most genera) the nomenclatural transfer of species to their correct genus. We recognise 26 genera, with reinstatement of two previously described genera ( Tod., R. Vig.), re-delimitation and expansion of several others (, , and ), contraction of s.s. and description of four new ones (, , and ), and make 75 new nomenclatural combinations in this new generic system.
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http://dx.doi.org/10.3897/phytokeys.71.9203DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5558824PMC
October 2016

Floral evolution and phylogeny of the Dialioideae, a diverse subfamily of tropical legumes.

Am J Bot 2017 Jul 14;104(7):1019-1041. Epub 2017 Jul 14.

Institut de Recherche en Biologie Végétale and Département de Sciences Biologiques, Université de Montréal, 4101 rue Sherbrooke Est, Montréal, Québec, H1X 2B2, Canada.

Premise Of The Study: The Dialioideae is an early diverging clade of caesalpinioid legumes containing approximately 85 species in 17 genera. Dialioideae floral morphology is highly variable and may provide clues to caesalpinioid evolution, but a well-resolved phylogeny is needed. Here, we have carried out a comprehensive morphological study of 78 Dialioideae and four outgroup species.

Methods: For all available Dialioideae DNA samples, the plastid and introns were sequenced. A combined phylogenetic analysis using the parsimony criterion was completed on a reduced taxon set for which both molecular and morphological data were available. Highly supported clades from the strict consensus tree of this analysis were then used to constrain the nodes of a second analysis on an expanded taxon set with missing molecular data for some taxa.

Key Results: Several new, highly supported relationships have been discovered at the species and genus levels. The loss of the antepetalous stamen whorl was found to be a synapomorphy for most of the clade.

Conclusions: A high degree of organ loss is common in the Dialioideae and often results in a bilaterally symmetrical flower. The absence of consistent morphological features in the Dialioideae, coupled with the small size of each florally diagnosed genus, suggests a lack of canalization in the floral evolution in early diverging legume lineages.
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http://dx.doi.org/10.3732/ajb.1600436DOI Listing
July 2017

A new species of (Leguminosae, Caesalpinioideae) from the western Río Balsas Depression, Mexico.

PhytoKeys 2017 9(76):31-38. Epub 2017 Jan 9.

Comparative Plant and Fungal Biology Department, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AB, U.K.

A new legume species from a seasonally dry forest of the Western Río Balsas Depression, in the states of Guerrero and Michoacán, Mexico, , is herein described and illustrated. The new species shows morphological affinities with , from which it is distinguished in having fewer leaflets per pinna, mature leaflets disposed toward the upper half of the pinnae rachises, long inflorescences on curved slender peduncles, abundant red glands on its flowers and inflorescences, and its fruit glabrous with red stipitate glands at maturity. A taxonomic key to the Río Balsas Depression species of is included.
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http://dx.doi.org/10.3897/phytokeys.76.10921DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5301983PMC
January 2017

Maximising Synergy among Tropical Plant Systematists, Ecologists, and Evolutionary Biologists.

Trends Ecol Evol 2017 04 16;32(4):258-267. Epub 2017 Feb 16.

Jardin Botanico de Missouri, Oxapampa, Peru.

Closer collaboration among ecologists, systematists, and evolutionary biologists working in tropical forests, centred on studies within long-term permanent plots, would be highly beneficial for their respective fields. With a key unifying theme of the importance of vouchered collection and precise identification of species, especially rare ones, we identify four priority areas where improving links between these communities could achieve significant progress in biodiversity and conservation science: (i) increasing the pace of species discovery; (ii) documenting species turnover across space and time; (iii) improving models of ecosystem change; and (iv) understanding the evolutionary assembly of communities and biomes.
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http://dx.doi.org/10.1016/j.tree.2017.01.007DOI Listing
April 2017

A molecular phylogeny reveals the Cuban enigmatic genus Behaimia as a new piece in the Brongniartieae puzzle of papilionoid legumes.

Mol Phylogenet Evol 2017 04 9;109:191-202. Epub 2017 Jan 9.

National Institute of Science and Technology in Interdisciplinary and Transdisciplinary Studies in Ecology and Evolution (INCT IN-TREE), Instituto de Biologia, Universidade Federal da Bahia, Rua Barão de Jeremoabo, s.n., Ondina, 40170-115 Salvador, Bahia, Brazil.

The papilionoid legume tribe Brongniartieae comprises a collection of 15 genera with disparate morphologies that were previously positioned in at least four remotely related tribes. The Brongniartieae displays a wide geographical disjunction between Australia and the New World and previous phylogenetic studies had provided conflicting results about the relationships between the American and Australian genera. We carry out phylogenetic analyses of (1) a plastid matK dataset extensively sampled across legumes to solve the enigmatic relationship of the Cuban-endemic monospecific genus Behaimia; and (2) multilocus datasets with focus on all genera ever referred to Brongniartieae. These analyses resulted in a well-resolved and strongly-supported phylogenetic tree of the Brongniartieae. The monophyly of all American genera of Brongniartieae is strongly supported. The doubtful position of the Australian genus Plagiocarpus is resolved within a clade comprising all Australian genera. Behaimia has been traditionally classified in tribe Millettieae, but our new molecular data and re-assessment of morphological traits have resolved the genus within the early-branching papilionoid tribe Brongniartieae. Characters including the pinnately multifoliolate (vs. unifoliolate) leaves, a sessile (vs. stipitate) ovary, and an indehiscent or late dehiscent one-seeded pod distinguish Behaimia from its closer relatives, the South American genera Cyclolobium and Limadendron.
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http://dx.doi.org/10.1016/j.ympev.2017.01.001DOI Listing
April 2017

The evolutionary dynamics of ancient and recent polyploidy in the African semiaquatic species of the legume genus Aeschynomene.

New Phytol 2016 08 7;211(3):1077-91. Epub 2016 Apr 7.

Laboratoire des Symbioses Tropicales et Méditerranéennes, IRD, UMR LSTM, Campus International de Baillarguet, 34398, Montpellier, France.

The legume genus Aeschynomene is notable in the ability of certain semiaquatic species to develop nitrogen-fixing stem nodules. These species are distributed in two clades. In the first clade, all the species are characterized by the use of a unique Nod-independent symbiotic process. In the second clade, the species use a Nod-dependent symbiotic process and some of them display a profuse stem nodulation as exemplified in the African Aeschynomene afraspera. To facilitate the molecular analysis of the symbiotic characteristics of such legumes, we took an integrated molecular and cytogenetic approach to track occurrences of polyploidy events and to analyze their impact on the evolution of the African species of Aeschynomene. Our results revealed two rounds of polyploidy: a paleopolyploid event predating the African group and two neopolyploid speciations, along with significant chromosomal variations. Hence, we found that A. afraspera (8x) has inherited the contrasted genomic properties and the stem-nodulation habit of its parental lineages (4x). This study reveals a comprehensive picture of African Aeschynomene diversification. It notably evidences a history that is distinct from the diploid Nod-independent clade, providing clues for the identification of the specific determinants of the Nod-dependent and Nod-independent symbiotic processes, and for comparative analysis of stem nodulation.
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http://dx.doi.org/10.1111/nph.13956DOI Listing
August 2016

Monomethyl ethers of 4,5-dihydroxypipecolic acid from Petaladenium urceoliferum: Enigmatic chemistry of an enigmatic legume.

Phytochemistry 2015 Aug 24;116:198-202. Epub 2015 Mar 24.

Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.

Leaves of Petaladenium (Leguminosae), an Amazonian monospecific genus recently revealed as a member of the Amburaneae clade among the earliest-diverging papilionoid legumes, were found to accumulate three monomethyl ethers of 4,5-dihydroxypipecolic acids. These were characterised by spectroscopic means as the (2S,4S,5R) and (2S,4R,5S) epimers of 5-hydroxy-4-methoxypipecolic acid and (2S,4R,5R)-4-hydroxy-5-methoxypipecolic acid. These compounds were not detected in any other genera in the Amburaneae clade or the wider Angylocalyceae-Dipterygeae-Amburaneae (ADA) clade of papilionoid legumes. Hydroxypipecolic acids, however, were detected in leaves of Myrocarpus and Myroxylon (sister genera in the Amburaneae clade), Angylocalyx and Xanthocercis (sister genera in the Angylocalyceae clade) and Monopteryx (Dipterygeae clade), and were also present in Petaladenium. Iminosugars, known to be accumulated by all four genera in the Angylocalyceae clade (Alexa, Angylocalyx, Castanospermum and Xanthocercis), were found to be characteristic of this group within the ADA clade.
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http://dx.doi.org/10.1016/j.phytochem.2015.02.026DOI Listing
August 2015

The distribution of glutathione and homoglutathione in leaf, root and seed tissue of 73 species across the three sub-families of the Leguminosae.

Phytochemistry 2015 Jul 6;115:175-83. Epub 2015 Feb 6.

Department of Comparative Plant and Fungal Biology, Royal Botanic Gardens, Kew, Wakehurst Place, Ardingly, West Sussex RH17 6TN, UK. Electronic address:

Homoglutathione (γ-glutamyl-cysteinyl-β-alanine) is a homologue of glutathione (γ-glutamyl-cysteinyl-glycine), which is a ubiquitous and indispensable tripeptide in eukaryotes with multi-facetted functions, many of which relate to cellular redox regulation. Homoglutathione is unique to the Leguminosae family, but studies of its occurrence have been restricted to the Papilionoideae subfamily, and almost exclusively to crop species. To determine whether the distribution of homoglutathione in the Leguminosae has a phylogenetic basis the occurrence of homoglutathione was investigated in the leaves, roots and seeds of 73 wild species of Leguminosae, representing 30 tribes across the Caesalpinioideae, Mimosoideae and Papilionoideae subfamilies. Homoglutathione was found only in the Papilionoideae, and was generally restricted to the 'Old World Clade'. It is proposed that homoglutathione may have arisen following a whole genome duplication event after the divergence of the Old World Clade. Homoglutathione is believed to fulfil the same functional roles as glutathione, but this study showed that homoglutathione and glutathione have different tissue-specific distribution patterns. Homoglutathione tended to occur more frequently in root tissue, and higher concentrations were found in leaves and roots, whereas glutathione tended to be present at the highest concentrations in seeds. This may reflect a distinct role for homoglutathione, particularly in roots, or an inability of homoglutathione to functionally replace glutathione in reproductive tissues. However, no relationships with environmental factors or nodulation were observed. Greater understanding of the factors that influence homoglutathione distribution may help to elucidate its unique function in some legume species.
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http://dx.doi.org/10.1016/j.phytochem.2015.01.011DOI Listing
July 2015

Maximizing the phylogenetic diversity of seed banks.

Conserv Biol 2015 Apr 5;29(2):370-81. Epub 2014 Sep 5.

School of Geography and the Environment, University of Oxford, South Parks Road, Oxford, OX1 3QY, United Kingdom.

Ex situ conservation efforts such as those of zoos, botanical gardens, and seed banks will form a vital complement to in situ conservation actions over the coming decades. It is therefore necessary to pay the same attention to the biological diversity represented in ex situ conservation facilities as is often paid to protected-area networks. Building the phylogenetic diversity of ex situ collections will strengthen our capacity to respond to biodiversity loss. Since 2000, the Millennium Seed Bank Partnership has banked seed from 14% of the world's plant species. We assessed the taxonomic, geographic, and phylogenetic diversity of the Millennium Seed Bank collection of legumes (Leguminosae). We compared the collection with all known legume genera, their known geographic range (at country and regional levels), and a genus-level phylogeny of the legume family constructed for this study. Over half the phylogenetic diversity of legumes at the genus level was represented in the Millennium Seed Bank. However, pragmatic prioritization of species of economic importance and endangerment has led to the banking of a less-than-optimal phylogenetic diversity and prioritization of range-restricted species risks an underdispersed collection. The current state of the phylogenetic diversity of legumes in the Millennium Seed Bank could be substantially improved through the strategic banking of relatively few additional taxa. Our method draws on tools that are widely applied to in situ conservation planning, and it can be used to evaluate and improve the phylogenetic diversity of ex situ collections.
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http://dx.doi.org/10.1111/cobi.12390DOI Listing
April 2015

Bioactive compounds from Stuhlmannia moavi from the Madagascar dry forest.

Bioorg Med Chem 2013 Dec 1;21(24):7591-4. Epub 2013 Nov 1.

Department of Chemistry and the Virginia Tech Center for Drug Discovery, M/C 0212, Virginia Tech, Blacksburg, VA 24061, USA.

Bioassay-directed fractionation of the leaf and root extracts of the antiproliferative Madagascar plant Stuhlmannia moavi afforded 6-acetyl-5,8-dihydroxy-2-methoxy-7-methyl-1,4-naphthoquinone (stuhlmoavin, 1) as the most active compound, with an IC50 value of 8.1 μM against the A2780 human ovarian cancer cell line, as well as the known homoisoflavonoid bonducellin (2) and the stilbenoids 3,4,5'-trihydroxy-3'-methoxy-trans-stilbene (3), piceatannol (4), resveratrol (5), rhapontigenin (6), and isorhapontigenin (7). The structure elucidation of all compounds was based on NMR and mass spectroscopic data, and the structure of 1 was confirmed by a single crystal X-ray analysis. Compounds 2-5 showed weak A2780 activities, with IC50 values of 10.6, 54.0, 41.0, and 74.0 μM, respectively. Compounds 1-3 also showed weak antimalarial activity against Plasmodium falciparum with IC50 values of 23, 26, and 27 μM, respectively.
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http://dx.doi.org/10.1016/j.bmc.2013.10.038DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3907118PMC
December 2013

Distinct chemotypes of Tephrosia vogelii and implications for their use in pest control and soil enrichment.

Phytochemistry 2012 Jun 4;78:135-46. Epub 2012 Apr 4.

Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK.

Tephrosia vogelii Hook. f. (Leguminosae) is being promoted as a pest control and soil enrichment agent for poorly-resourced small-scale farmers in southern and eastern Africa. This study examined plants being cultivated by farmers and found two chemotypes. Chemotype 1 (C1) contained rotenoids, including deguelin, rotenone, sarcolobine, tephrosin and α-toxicarol, required for pest control efficacy. Rotenoids were absent from chemotype 2 (C2), which was characterised by prenylated flavanones, including the previously unrecorded examples (2S)-5,7-dimethoxy-8-(3-hydroxy-3-methylbut-1Z-enyl)flavanone, (2S)-5,7-dimethoxy-8-(3-methylbut-1,3-dienyl)flavanone, (2S)-4'-hydroxy-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone, (2S)-5-methoxy-6″,6″-dimethyl-4″,5″-dihydrocyclopropa[4″,5″]furano[2″,3″:7,8]flavanone, (2S)-7-hydroxy-5-methoxy-8-prenylflavanone, and (2R,3R)-3-hydroxy-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone. The known compounds (2S)-5-methoxy-6″,6″-dimethylpyrano[2″,3″:7,8]flavanone (obovatin 5-methyl ether) and 5,7-dimethoxy-8-(3-hydroxy-3-methylbut-1Z-enyl)flavone (Z-tephrostachin) were also found in C2. This chemotype, although designated Tephrosia candida DC. in collections originating from the World Agroforestry Centre (ICRAF), was confirmed to be T. vogelii on the basis of morphological comparison with verified herbarium specimens and DNA sequence analysis. Sampling from 13 locations in Malawi where farmers cultivate Tephrosia species for insecticidal use indicated that almost 1 in 4 plants were T. vogelii C2, and so were unsuitable for this application. Leaf material sourced from a herbarium specimen of T. candida contained most of the flavanones found in T. vogelii C2, but no rotenoids. However, the profile of flavonol glycosides was different to that of T. vogelii C1 and C2, with 6-hydroxy-kaempferol 6-methyl ether as the predominant aglycone rather than kaempferol and quercetin. The structures of four unrecorded flavonol glycosides present in T. candida were determined using cryoprobe NMR spectroscopy and MS as the 3-O-α-rhamnopyranosyl(1→6)-β-galactopyranoside-7-O-α-rhamnopyranoside, 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside, 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside-7-O-α-rhamnopyranoside, and 3-O-α-rhamnopyranosyl(1→2)[(3-O-E-feruloyl)-α-rhamnopyranosyl(1→6)]-β-galactopyranosides of 6-hydroxykaempferol 6-methyl ether. Tentative structures for a further 37 flavonol glycosides of T. candida were assigned by LC-MS/MS. The correct chemotype of T. vogelii (i.e. C1) needs to be promoted for use by farmers in pest control applications.
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http://dx.doi.org/10.1016/j.phytochem.2012.02.025DOI Listing
June 2012

Acylated flavonol tri- and tetraglycosides in the flavonoid metabolome of Cladrastis kentukea (Leguminosae).

Phytochemistry 2011 Apr 1;72(4-5):372-84. Epub 2011 Feb 1.

Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.

The foliar metabolome of Cladrastis kentukea (Leguminosae) contains a complex mixture of flavonoids including acylated derivatives of the 3-O-rhamnosyl(1→2)[rhamnosyl(1→6)]-galactosides of kaempferol and quercetin and their 7-O-rhamnosides, together with an array of non-acylated kaempferol and quercetin di-, tri- and tetraglycosides. Thirteen of the acylated flavonoids, 12 of which had not been reported previously, were characterised by spectroscopic and chemical methods. Eight of these were the four isomers of kaempferol 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E/Z-p-coumaroyl-β-d-galactopyranoside) and their 7-O-α-l-rhamnopyranosides, and three were isomers of quercetin 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E/Z-p-coumaroyl-β-d-galactopyranoside) - the remaining 4Z isomer was identified by LC-UV-MS analysis of a crude extract. The final two acylated flavonoids characterised by NMR were the 3E and 4E isomers of kaempferol 3-O-α-l-rhamnopyranosyl(1→2)[α-l-rhamnopyranosyl(1→6)]-(3/4-O-E-feruloyl-β-d-galactopyranoside)-7-O-α-l-rhamnopyranoside while the 3Z and 4Z isomers were again detected by LC-UV-MS. Using the observed fragmentation behaviour of the isolated compounds following a variety of MS experiments, a further 18 acylated flavonoids were given tentative structures by LC-MS analysis of a crude extract. Acylated flavonoids were absent from the flowers of C. kentukea, which contained an array of non-acylated kaempferol and quercetin glycosides. Immature fruits contained kaempferol 3-O-α-rhamnopyranosyl(1→2)[α-rhamnopyranosyl(1→6)]-β-galactopyranoside and its 7-O-α-rhamnopyranoside as the major flavonoids with acylated flavonoids, different from those in the leaves, only present as minor constituents. The presence of acylated flavonoids distinguishes the foliar flavonoid metabolome of C. kentukea from that of a closely related legume, Styphnolobium japonicum, which contains a similar range of non-acylated flavonoids.
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http://dx.doi.org/10.1016/j.phytochem.2010.12.017DOI Listing
April 2011

Contrasting plant diversification histories within the Andean biodiversity hotspot.

Proc Natl Acad Sci U S A 2010 Aug 19;107(31):13783-7. Epub 2010 Jul 19.

Royal Botanic Garden Edinburgh, Edinburgh EH6 4NY, United Kingom.

The Andes are the most species-rich global biodiversity hotspot. Most research and conservation attention in the Andes has focused on biomes such as rain forest, cloud forest, and páramo, where much plant species diversity is the hypothesized result of rapid speciation associated with the recent Andean orogeny. In contrast to these mesic biomes, we present evidence for a different, older diversification history in seasonally dry tropical forests (SDTF) occupying rain-shadowed inter-Andean valleys. High DNA sequence divergence in Cyathostegia mathewsii, a shrub endemic to inter-Andean SDTF, indicates isolation for at least 5 million years of populations separated by only ca. 600 km of high cordillera in Peru. In conjunction with fossil evidence indicating the presence of SDTF in the Andes in the late Miocene, our data suggest that the disjunct small valley pockets of inter-Andean SDTF have persisted over millions of years. These forests are rich in endemic species but massively impacted, and merit better representation in future plans for science and conservation in Andean countries.
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http://dx.doi.org/10.1073/pnas.1001317107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2922214PMC
August 2010

Flavonoid glycosides of the black locust tree, Robinia pseudoacacia (Leguminosae).

Phytochemistry 2010 Mar 28;71(4):479-86. Epub 2009 Nov 28.

Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.

Four flavone glycosides isolated from extracts of the leaves of Robinia pseudoacacia (Leguminosae) were characterised by spectroscopic and chemical methods as the 7-O-beta-d-glucuronopyranosyl-(1-->2)[alpha-l-rhamnopyranosyl-(1-->6)]-beta-d-glucopyranosides of acacetin (5,7-dihydroxy-4'-methoxyflavone), apigenin (5,7,4'-trihydroxyflavone), diosmetin (5,7,3'-trihydroxy-4'-methoxyflavone) and luteolin (5,7,3',4'-tetrahydroxyflavone). Assignment of glycosidic (1)H and (13)C resonances in their NMR spectra was facilitated by (2)J(HC) correlations detected using the H2BC (heteronuclear two-bond correlation) pulse sequence. Spectroscopic analysis of two known triglycosides, acacetin 7-O-beta-d-glucopyranosyl-(1-->2)[alpha-l-rhamnopyranosyl-(1-->6)]-beta-d-glucopyranoside (previously unrecorded from this species) and acacetin 7-O-beta-d-xylopyranosyl-(1-->2)[alpha-l-rhamnopyranosyl-(1-->6)]-beta-d-glucopyranoside ('acacetin trioside'), enabled inconsistencies in the literature relating to these structures to be resolved. Comparison of the flavonoid chemistry of leaves and flowers of R. pseudoacacia using LC-UV and LC-MS showed that flavone 7-O-glycosides, particularly of acacetin, predominated in the former, whereas the latter comprised mainly flavonol 3,7-di-O-glycosides, including several examples new to this species. Tissue dependent differences in flavonoid chemistry were also evident from the glycosylation patterns of the compounds.
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http://dx.doi.org/10.1016/j.phytochem.2009.10.024DOI Listing
March 2010

Flavonol tetraglycosides from fruits of Styphnolobium japonicum (Leguminosae) and the authentication of Fructus Sophorae and Flos Sophorae.

Phytochemistry 2009 Apr 15;70(6):785-94. Epub 2009 May 15.

Royal Botanic Gardens, Kew, Richmond, Surrey, UK.

The dried fruits and seeds of Styphnolobium japonicum (L.) Schott (syn. Sophora japonica L.) are used in traditional Chinese medicine and known as Fructus Sophorae or Huai Jiao. The major flavonoids in these fruits and seeds were studied by LC-MS and other spectroscopic techniques to aid the chemical authentication of Fructus Sophorae. Among the flavonoids were two previously unreported kaempferol glycosides: kaempferol 3-O-beta-glucopyranosyl(1-->2)-beta-galactopyranoside-7-O-alpha-rhamnopyranoside and kaempferol 3-O-beta-xylopyranosyl(1-->3)-alpha-rhamnopyranosyl(1-->6)[beta-glucopyranosyl(1-->2)]-beta-glucopyranoside, the structures of which were determined by NMR. Two further tetraglycosides were identified for the first time in S. japonicum as kaempferol 3-O-beta-glucopyranosyl(1-->2)[alpha-rhamnopyranosyl(1-->6)]-beta-glucopyranoside-7-O-alpha-rhamnopyranoside and kaempferol 3-O-beta-glucopyranosyl(1-->2)[alpha-rhamnopyranosyl(1-->6)]-beta-galactopyranoside-7-O-alpha-rhamnopyranoside; the latter was the main flavonoid in mature seeds. The chromatographic profiles of 27 recorded flavonoids were relatively consistent among fruits of similar ages collected from five trees of S. japonicum, and those of maturing unripe and ripe fruits were similar to a market sample of Fructus Sophorae, and thus provide useful markers for authentication of this herbal ingredient. The flower buds (Huai Mi) and flowers (Huai Hua) of S. japonicum (collectively Flos Sophorae) contained rutin as the main flavonoid and lacked the flavone glycosides that were present in flower buds and flowers of Sophora flavescens Ait., reported to be occasional substitutes for Flos Sophorae. The single major flavonoid in fruits of S. flavescens was determined as 3'-hydroxydaidzein.
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http://dx.doi.org/10.1016/j.phytochem.2009.04.003DOI Listing
April 2009

Flavonol pentaglycosides of Cordyla (Leguminosae: Papilionoideae: Swartzieae): distribution and taxonomic implications.

Phytochemistry 2008 Sep 14;69(12):2329-35. Epub 2008 Jul 14.

Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK.

A survey of foliar flavonoids in the swartzioid legume genus Cordyla s.l. revealed that three species, C. haraka, C. pinnata and C. richardii, were rich in flavonol pentaglycosides. Their structures were elucidated by spectroscopic and chemical methods as the 3-O-alpha-L-rhamnopyranosyl(1-->3)-alpha-L-rhamnopyranosyl(1-->2)[alpha-L-rhamnopyranosyl(1-->6)]-beta-D-galactopyranoside-7-O-alpha-L-rhamnopyranosides of quercetin and kaempferol (cordylasins A and B, respectively). These compounds were not found in the remaining species, C. africana, C. densiflora, C. madagascariensis (two subspecies) and C. somalensis, which exhibited different profiles of flavonoid glycosides. The distribution of flavonol pentaglycosides in Cordyla s.l. does not support a recent proposal to place both C. haraka and C. madagascariensis in the genus Dupuya [Kirkbride, J.H., 2005. Dupuya, a new genus of Malagasy legumes (Fabaceae). Novon 15, 305-314]. The generic relationship between Cordyla s.l. and Mildbraediodendron is also reassessed on the basis of chemical characters, as the O-linked tetrasaccharide that characterises cordylasins A and B is the same as that found in mildbraedin (kaempferol 3-O-alpha-l-rhamnopyranosyl(1-->3)-alpha-l-rhamnopyranosyl(1-->2)[alpha-l-rhamnopyranosyl(1-->6)]-beta-D-galactopyranoside), the main foliar flavonoid of Mildbraediodendron excelsum. Mildbraedin itself was found to be a minor constituent of leaflet extracts of C. haraka, C. pinnata and C. richardii, and a major constituent of C. somalensis.
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http://dx.doi.org/10.1016/j.phytochem.2008.05.026DOI Listing
September 2008

Cryptic speciation in the Caesalpinia hintonii complex (Leguminosae: Caesalpinioideae) in a seasonally dry Mexican forest.

Ann Bot 2007 Dec 2;100(6):1307-14. Epub 2007 Oct 2.

Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México, México.

Background And Aims: [corrected] The Caesalpinia hintonii group comprises six species of endemic shrubs or trees, C. epifanioi, C. hintonii, C. laxa, C. macvaughii, C. melanadenia and C. oyamae, found in scattered patches of seasonally dry forest in the Río Balsas depression and the neighbouring Tehuacán-Cuicatlán valley, which are part of the Mexican morphotectonic province of Sierra Madre del Sur. An evaluation is made of phylogeographic patterns and genetic diversity with a phylogenetic analysis of the C. hintonii complex in order to study the dynamics of speciation in this endemic group of legumes.

Methods: A phylogeographic study based on four highly variable non-coding plastid regions (trnL intron, trnL-F intergenic spacer, trnH-psbA intergenic spacer, and accD-psaI intergenic spacer) was carried out for the Caesalpinia hintonii complex. Five of the six taxa of the C. hintonii complex were included.

Key Results And Conclusions: The plastid analyses involving multiple accessions of each taxon from throughout their ranges resolved C. epifanioi and C. hintonii as well-supported clusters, but C. oyamae has two unexpectedly divergent lineages. Two well-supported geographic clades: eastern (C. epifanioi, C. melanadenia and C. oyamae) and western (C. hintonii and C. macvaughii) were established. The analyses performed provide evidence of recent morphostatic radiation in C. oyamae resulting from isolation and local adaptation. This pattern of genetic differentiation without morphological divergence may be a model that fits many groups of tropical woody taxa inhabiting similarly dry forests subjected to shifting selection.
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http://dx.doi.org/10.1093/aob/mcm213DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2759254PMC
December 2007

A phylogenetic reappraisal of the Peltophorum group (Caesalpinieae: Leguminosae) based on the chloroplast trnL-F, rbcL and rps16 sequence data.

Am J Bot 2005 Aug;92(8):1359-71

The School of Plant Sciences, The University of Reading, Whiteknights, Reading, RG6 6AS, UK;

The monophyly of the Peltophorum group, one of nine informal groups recognized by Polhill in the Caesalpinieae, was tested using sequence data from the trnL-F, rbcL, and rps16 regions of the chloroplast genome. Exemplars were included from all 16 genera of the Peltophorum group, and from 15 genera representing seven of the other eight informal groups in the tribe. The data were analyzed separately and in combined analyses using parsimony and Bayesian methods. The analysis method had little effect on the topology of well-supported relationships. The molecular data recovered a generally well-supported phylogeny with many intergeneric relationships resolved. Results show that the Peltophorum group as currently delimited is polyphyletic, but that eight genera plus one undescribed genus form a core Peltophorum group, which is referred to here as the Peltophorum group sensu stricto. These genera are Bussea, Conzattia, Colvillea, Delonix, Heteroflorum (inedit.), Lemuropisum, Parkinsonia, Peltophorum, and Schizolobium. The remaining eight genera of the Peltophorum group s.l. are distributed across the Caesalpinieae. Morphological support for the redelimited Peltophorum group and the other recovered clades was assessed, and no unique synapomorphy was found for the Peltophorum group s.s. A proposal for the reclassification of the Peltophorum group s.l. is presented.
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http://dx.doi.org/10.3732/ajb.92.8.1359DOI Listing
August 2005
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