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Leung A, Patel R, Chirachon V, Stata M, Macfarlane TD, Ludwig M, Busch FA, Sage TL, Sage RF. Tribulus (Zygophyllaceae) as a case study for the evolution of C 2 and C 4 photosynthesis. PLANT, CELL & ENVIRONMENT 2024; 47:3541-3560. [PMID: 39132738 DOI: 10.1111/pce.15069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 07/19/2024] [Accepted: 07/23/2024] [Indexed: 08/13/2024]
Abstract
C2 photosynthesis is a photosynthetic pathway in which photorespiratory CO2 release and refixation are enhanced in leaf bundle sheath (BS) tissues. The evolution of C2 photosynthesis has been hypothesized to be a major step in the origin of C4 photosynthesis, highlighting the importance of studying C2 evolution. In this study, physiological, anatomical, ultrastructural, and immunohistochemical properties of leaf photosynthetic tissues were investigated in six non-C4 Tribulus species and four C4 Tribulus species. At 42°C, T. cristatus exhibited a photosynthetic CO2 compensation point in the absence of respiration (C*) of 21 µmol mol-1, below the C3 mean C* of 73 µmol mol-1. Tribulus astrocarpus had a C* value at 42°C of 55 µmol mol-1, intermediate between the C3 species and the C2 T. cristatus. Glycine decarboxylase (GDC) allocation to BS tissues was associated with lower C*. Tribulus cristatus and T. astrocarpus allocated 86% and 30% of their GDC to the BS tissues, respectively, well above the C3 mean of 11%. Tribulus astrocarpus thus exhibits a weaker C2 (termed sub-C2) phenotype. Increased allocation of mitochondria to the BS and decreased length-to-width ratios of BS cells, were present in non-C4 species, indicating a potential role in C2 and C4 evolution.
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Affiliation(s)
- Arthur Leung
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Ria Patel
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Varosak Chirachon
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Matt Stata
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- Departments of Biochemistry and Molecular Biology, Plant Biology, and Plant, Soil, and Microbial Sciences, Plant Resilience Institute, Michigan State University, East Lansing, Michigan, USA
| | - Terry D Macfarlane
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia, Australia
- Department of Biodiversity, Conservation and Attractions, Western Australian Herbarium, Perth, Western Australia, Australia
| | - Martha Ludwig
- School of Molecular Sciences, University of Western Australia, Crawley, Western Australia, Australia
| | - Florian A Busch
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
- School of Biosciences and Birmingham Institute of Forest Research, University of Birmingham, Edgbaston, Birmingham, UK
| | - Tammy L Sage
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
| | - Rowan F Sage
- Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada
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2
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Berasategui JA, Žerdoner Čalasan A, Zizka A, Kadereit G. Global distribution, climatic preferences and photosynthesis-related traits of C 4 eudicots and how they differ from those of C 4 grasses. Ecol Evol 2023; 13:e10720. [PMID: 37964791 PMCID: PMC10641307 DOI: 10.1002/ece3.10720] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 10/25/2023] [Accepted: 10/30/2023] [Indexed: 11/16/2023] Open
Abstract
C₄ is one of three known photosynthetic processes of carbon fixation in flowering plants. It evolved independently more than 61 times in multiple angiosperm lineages and consists of a series of anatomical and biochemical modifications to the ancestral C3 pathway increasing plant productivity under warm and light-rich conditions. The C4 lineages of eudicots belong to seven orders and 15 families, are phylogenetically less constrained than those of monocots and entail an enormous structural and ecological diversity. Eudicot C4 lineages likely evolved the C4 syndrome along different evolutionary paths. Therefore, a better understanding of this diversity is key to understanding the evolution of this complex trait as a whole. By compiling 1207 recognised C4 eudicots species described in the literature and presenting trait data among these species, we identify global centres of species richness and of high phylogenetic diversity. Furthermore, we discuss climatic preferences in the context of plant functional traits. We identify two hotspots of C4 eudicot diversity: arid regions of Mexico/Southern United States and Australia, which show a similarly high number of different C4 eudicot genera but differ in the number of C4 lineages that evolved in situ. Further eudicot C4 hotspots with many different families and genera are in South Africa, West Africa, Patagonia, Central Asia and the Mediterranean. In general, C4 eudicots are diverse in deserts and xeric shrublands, tropical and subtropical grasslands, savannas and shrublands. We found C4 eudicots to occur in areas with less annual precipitation than C4 grasses which can be explained by frequently associated adaptations to drought stress such as among others succulence and salt tolerance. The data indicate that C4 eudicot lineages utilising the NAD-ME decarboxylating enzyme grow in drier areas than those using the NADP-ME decarboxylating enzyme indicating biochemical restrictions of the later system in higher temperatures. We conclude that in most eudicot lineages, C4 evolved in ancestrally already drought-adapted clades and enabled these to further spread in these habitats and colonise even drier areas.
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Affiliation(s)
- Jessica A. Berasategui
- Prinzessin Therese von Bayern Lehrstuhl für Systematik, Biodiversität & Evolution der PflanzenLudwig‐Maximilians Universität MünchenMünchenGermany
- Institute for Molecular PhysiologyJohannes Gutenberg‐University MainzMainzGermany
| | - Anže Žerdoner Čalasan
- Prinzessin Therese von Bayern Lehrstuhl für Systematik, Biodiversität & Evolution der PflanzenLudwig‐Maximilians Universität MünchenMünchenGermany
| | - Alexander Zizka
- Department of BiologyPhilipps‐University MarburgMarburgGermany
| | - Gudrun Kadereit
- Prinzessin Therese von Bayern Lehrstuhl für Systematik, Biodiversität & Evolution der PflanzenLudwig‐Maximilians Universität MünchenMünchenGermany
- Botanischer Garten München‐Nymphenburg und Botanische Staatssammlung MünchenStaatliche Naturwissenschaftliche Sammlungen BayernsMünchenGermany
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Young SNR, Dunning LT, Liu H, Stevens CJ, Lundgren MR. C4 trees have a broader niche than their close C3 relatives. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3189-3204. [PMID: 35293994 PMCID: PMC9126736 DOI: 10.1093/jxb/erac113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 03/12/2022] [Indexed: 06/14/2023]
Abstract
Previous studies have demonstrated the ecological sorting of herbaceous C3 and C4 species along gradients of precipitation and temperature: C4 herbaceous species typically occupy drier and warmer environments than their C3 relatives. However, it is unclear if this pattern holds true for C4 tree species, which are unique to Euphorbiaceae and found only on the Hawaiian Islands. Here, we combine occurrence data with local environmental and soil datasets to, for the first time, distinguish the ecological factors associated with photosynthetic diversification in the tree life form. These data are presented within a phylogenetic framework. We show that C3 and C4 trees inhabit similar environments, but that C4 photosynthesis expands the ecological niche in trees relative to that of C3 tree species. In particular, when compared with C3 trees, C4 trees moved into higher elevation habitats with characteristically sparse vegetation (and thus greater sunlight) and cooler temperatures, a pattern which contrasts with that of herbaceous species. Understanding the relationship between C4 photosynthesis and ecological niche in tree species has implications for establishing how C4 photosynthesis has, in this rare instance, evolved in trees, and whether this unique combination of traits could be exploited from an engineering perspective.
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Affiliation(s)
- Sophie N R Young
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Luke T Dunning
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Hui Liu
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Guangzhou 510650, China
| | - Carly J Stevens
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
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Anest A, Charles-Dominique T, Maurin O, Millan M, Edelin C, Tomlinson KW. Evolving the structure: climatic and developmental constraints on the evolution of plant architecture. A case study in Euphorbia. THE NEW PHYTOLOGIST 2021; 231:1278-1295. [PMID: 33629359 DOI: 10.1111/nph.17296] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
Plant architecture strongly influences ecological performance, yet its role in plant evolution has not been explored in depth. By testing both phylogenetic and environmental signals, it is possible to separate architectural traits into four categories: development constraints (phylogenetic signal only); convergences (environmental dependency only); key confluences to the environmental driver (both); unknown (neither). We analysed the evolutionary history of the genus Euphorbia, a model clade with both high architectural diversity and a wide environmental range. We conducted comparative analyses of 193 Euphorbia species world-wide using 73 architectural traits, a dated phylogeny, and climate data. We identified 14 architectural types in Euphorbia based on trait combinations. We found 22 traits and three types representing convergences under climate groups, 21 traits and four types showing phylogenetic signal but no relation to climate, and 16 traits and five types with both climate and phylogenetic signals. Major drivers of architectural trait evolution likely include water stress in deserts (selected for succulence, continuous branching), frost disturbance in temperate systems (selected for simple, prostrate, short-lived shoots) and light competition (selected for arborescence). Simple architectures allowed resilience to disturbance, and frequent transitions into new forms. Complex architectures with functional specialisation developed under stable climates but have low evolvability.
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Affiliation(s)
- Artémis Anest
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | | | - Olivier Maurin
- Comparative Plant and Fungal Biology, Plant and Fungal Trees of Life, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, UK
| | - Mathieu Millan
- Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of the Witwatersrand, Johannesburg, Private Bag X3, WITS, 2050, South Africa
- Global Change Biology Group, Department of Botany and Zoology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - Claude Edelin
- French Institute of Pondicherry, No. 11, Post Box No. 33, Saint Louis Street, Pondicherry, 605 001, India
- UMR AMAP, CIRAD - TA A51/PS2, Montpellier Cedex 5, 34398, France
| | - Kyle W Tomlinson
- Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Menglun, Mengla, Yunnan, 666303, China
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5
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Wei N, Pérez-Escobar OA, Musili PM, Huang WC, Yang JB, Hu AQ, Hu GW, Grace OM, Wang QF. Plastome Evolution in the Hyperdiverse Genus Euphorbia (Euphorbiaceae) Using Phylogenomic and Comparative Analyses: Large-Scale Expansion and Contraction of the Inverted Repeat Region. FRONTIERS IN PLANT SCIENCE 2021; 12:712064. [PMID: 34421963 PMCID: PMC8372406 DOI: 10.3389/fpls.2021.712064] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/05/2021] [Indexed: 05/09/2023]
Abstract
With c. 2,000 species, Euphorbia is one of the largest angiosperm genera, yet a lack of chloroplast genome (plastome) resources impedes a better understanding of its evolution. In this study, we assembled and annotated 28 plastomes from Euphorbiaceae, of which 15 were newly sequenced. Phylogenomic and comparative analyses of 22 plastome sequences from all four recognized subgenera within Euphorbia revealed that plastome length in Euphorbia is labile, presenting a range of variation c. 42 kb. Large-scale expansions of the inverted repeat (IR) region were identified, and at the extreme opposite, the near-complete loss of the IR region (with only 355 bp left) was detected for the first time in Euphorbiaceae. Other structural variations, including gene inversion and duplication, and gene loss/pseudogenization, were also observed. We screened the most promising molecular markers from both intergenic and coding regions for phylogeny-based utilities, and estimated maximum likelihood and Bayesian phylogenies from four datasets including whole plastome sequences. The monophyly of Euphorbia is supported, and its four subgenera are recovered in a successive sister relationship. Our study constitutes the first comprehensive investigation on the plastome structural variation in Euphorbia and it provides resources for phylogenetic research in the genus, facilitating further studies on its taxonomy, evolution, and conservation.
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Affiliation(s)
- Neng Wei
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Royal Botanic Gardens, Kew, Richmond, United Kingdom
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | | | - Paul M. Musili
- East African Herbarium, National Museums of Kenya, Nairobi, Kenya
| | - Wei-Chang Huang
- Shanghai Chenshan Plant Science Research Center, Chinese Academy of Sciences, Chenshan Botanical Garden, Shanghai, China
| | - Jun-Bo Yang
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China
| | - Ai-Qun Hu
- Royal Botanic Gardens, Kew, Richmond, United Kingdom
| | - Guang-Wan Hu
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, China
- Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan, China
| | - Olwen M. Grace
- Royal Botanic Gardens, Kew, Richmond, United Kingdom
- *Correspondence: Olwen M. Grace,
| | - Qing-Feng Wang
- Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China
- Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan, China
- Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan, China
- Qing-Feng Wang,
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6
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Young SNR, Sack L, Sporck-Koehler MJ, Lundgren MR. Why is C4 photosynthesis so rare in trees? JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:4629-4638. [PMID: 32409834 PMCID: PMC7410182 DOI: 10.1093/jxb/eraa234] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 05/12/2020] [Indexed: 05/08/2023]
Abstract
Since C4 photosynthesis was first discovered >50 years ago, researchers have sought to understand how this complex trait evolved from the ancestral C3 photosynthetic machinery on >60 occasions. Despite its repeated emergence across the plant kingdom, C4 photosynthesis is notably rare in trees, with true C4 trees only existing in Euphorbia. Here we consider aspects of the C4 trait that could limit but not preclude the evolution of a C4 tree, including reduced quantum yield, increased energetic demand, reduced adaptive plasticity, evolutionary constraints, and a new theory that the passive symplastic phloem loading mechanism observed in trees, combined with difficulties in maintaining sugar and water transport over a long pathlength, could make C4 photosynthesis largely incompatible with the tree lifeform. We conclude that the transition to a tree habit within C4 lineages as well as the emergence of C4 photosynthesis within pre-existing trees would both face a series of challenges that together explain the global rarity of C4 photosynthesis in trees. The C4 trees in Euphorbia are therefore exceptional in how they have circumvented every potential barrier to the rare C4 tree lifeform.
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Affiliation(s)
- Sophie N R Young
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
| | - Lawren Sack
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, CA, USA
| | | | - Marjorie R Lundgren
- Lancaster Environment Centre, Lancaster University, Lancaster, UK
- Correspondence:
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7
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Khan A, Asaf S, Khan AL, Shehzad T, Al-Rawahi A, Al-Harrasi A. Comparative Chloroplast Genomics of Endangered Euphorbia Species: Insights into Hotspot Divergence, Repetitive Sequence Variation, and Phylogeny. PLANTS 2020; 9:plants9020199. [PMID: 32033491 PMCID: PMC7076480 DOI: 10.3390/plants9020199] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 01/16/2020] [Accepted: 01/17/2020] [Indexed: 11/30/2022]
Abstract
Euphorbia is one of the largest genera in the Euphorbiaceae family, comprising 2000 species possessing commercial, medicinal, and ornamental importance. However, there are very little data available on their molecular phylogeny and genomics, and uncertainties still exist at a taxonomic level. Herein, we sequence the complete chloroplast (cp) genomes of two species, E. larica and E. smithii, of the genus Euphorbia through next-generation sequencing and perform a comparative analysis with nine related genomes in the family. The results revealed that the cp genomes had similar quadripartite structure, gene content, and genome organization with previously reported genomes from the same family. The size of cp genomes ranged from 162,172 to 162,358 bp with 132 and 133 genes, 8 rRNAs, 39 tRNA in E. smithii and E. larica, respectively. The numbers of protein-coding genes were 85 and 86, with each containing 19 introns. The four-junction regions were studied and results reveal that rps19 was present at JLB (large single copy region and inverted repeat b junction) in E. larica where its complete presence was located in the IRb (inverted repeat b) region in E. smithii. The sequence comparison revealed that highly divergent regions in rpoC1, rpocB, ycf3, clpP, petD, ycf1, and ndhF of the cp genomes might provide better understanding of phylogenetic inferences in the Euphorbiaceae and order Malpighiales. Phylogenetic analyses of this study illustrate sister clades of E. smithii with E. tricullii and these species form a monophyletic clade with E. larica. The current study might help us to understand the genome architecture, genetic diversity among populations, and evolutionary depiction in the genera.
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Affiliation(s)
- Arif Khan
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman; (A.K.); (S.A.); (A.A.-R.)
- Genomics Group, Faculty of Biosciences and Aquaculture, Nord University, 8049 Bodø, Norway
| | - Sajjad Asaf
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman; (A.K.); (S.A.); (A.A.-R.)
| | - Abdul Latif Khan
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman; (A.K.); (S.A.); (A.A.-R.)
- Correspondence: (A.L.K.); (A.A.-H.)
| | - Tariq Shehzad
- Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, 2713 Doha, Qatar;
| | - Ahmed Al-Rawahi
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman; (A.K.); (S.A.); (A.A.-R.)
| | - Ahmed Al-Harrasi
- Natural and Medical Sciences Research Center, University of Nizwa, Nizwa 616, Oman; (A.K.); (S.A.); (A.A.-R.)
- Correspondence: (A.L.K.); (A.A.-H.)
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8
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Winter K, Garcia M, Virgo A, Holtum JAM. Operating at the very low end of the crassulacean acid metabolism spectrum: Sesuvium portulacastrum (Aizoaceae). JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:6561-6570. [PMID: 30535159 PMCID: PMC6883264 DOI: 10.1093/jxb/ery431] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 11/30/2018] [Indexed: 05/31/2023]
Abstract
Demonstration of crassulacean acid metabolism (CAM) in species with low usage of this system relative to C3-photosynthetic CO2 assimilation can be challenging experimentally but provides crucial information on the early steps of CAM evolution. Here, weakly expressed CAM was detected in the well-known pantropical coastal, leaf-succulent herb Sesuvium portulacastrum, demonstrating that CAM is present in the Sesuvioideae, the only sub-family of the Aizoaceae in which it had not yet been shown conclusively. In outdoor plots in Panama, leaves and stems of S. portulacastrum consistently exhibited a small degree of nocturnal acidification which, in leaves, increased during the dry season. In potted plants, nocturnal acidification was mainly facultative, as levels of acidification increased in a reversible manner following the imposition of short-term water-stress. In drought-stressed plants, nocturnal net CO2 exchange approached the CO2-compensation point, consistent with low rates of CO2 dark fixation sufficient to eliminate respiratory carbon loss. Detection of low-level CAM in S. portulacastrum adds to the growing number of species that cannot be considered C3 plants sensu stricto, although they obtain CO2 principally via the C3 pathway. Knowledge about the presence/absence of low-level CAM is critical when assessing trajectories of CAM evolution in lineages. The genus Sesuvium is of particular interest because it also contains C4 species.
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Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Milton Garcia
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Aurelio Virgo
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
| | - Joseph A M Holtum
- Smithsonian Tropical Research Institute, Balboa, Ancón, Republic of Panama
- Centre for Tropical Biodiversity and Climate Change, College of Science and Engineering, James Cook University, Townsville, Queensland, Australia
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9
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Ernst M, Nothias LF, van der Hooft JJJ, Silva RR, Saslis-Lagoudakis CH, Grace OM, Martinez-Swatson K, Hassemer G, Funez LA, Simonsen HT, Medema MH, Staerk D, Nilsson N, Lovato P, Dorrestein PC, Rønsted N. Assessing Specialized Metabolite Diversity in the Cosmopolitan Plant Genus Euphorbia L. FRONTIERS IN PLANT SCIENCE 2019; 10:846. [PMID: 31333695 PMCID: PMC6615404 DOI: 10.3389/fpls.2019.00846] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 06/13/2019] [Indexed: 05/02/2023]
Abstract
Coevolutionary theory suggests that an arms race between plants and herbivores yields increased plant specialized metabolite diversity and the geographic mosaic theory of coevolution predicts that coevolutionary interactions vary across geographic scales. Consequently, plant specialized metabolite diversity is expected to be highest in coevolutionary hotspots, geographic regions, which exhibit strong reciprocal selection on the interacting species. Despite being well-established theoretical frameworks, technical limitations have precluded rigorous hypothesis testing. Here we aim at understanding how geographic separation over evolutionary time may have impacted chemical differentiation in the cosmopolitan plant genus Euphorbia. We use a combination of state-of-the-art computational mass spectral metabolomics tools together with cell-based high-throughput immunomodulatory testing. Our results show significant differences in specialized metabolite diversity across geographically separated phylogenetic clades. Chemical structural diversity of the highly toxic Euphorbia diterpenoids is significantly reduced in species native to the Americas, compared to Afro-Eurasia. The localization of these compounds to young stems and roots suggest a possible ecological relevance in herbivory defense. This is further supported by reduced immunomodulatory activity in the American subclade as well as herbivore distribution patterns. We conclude that computational mass spectrometric metabolomics coupled with relevant ecological data provide a strong tool for exploring plant specialized metabolite diversity in a chemo-evolutionary framework.
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Affiliation(s)
- Madeleine Ernst
- Natural History Museum of Denmark, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Louis-Félix Nothias
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
| | - Justin J. J. van der Hooft
- Bioinformatics Group, Department of Plant Sciences, Wageningen University & Research, Wageningen, Netherlands
| | - Ricardo R. Silva
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
| | | | - Olwen M. Grace
- Comparative Plant and Fungal Biology, Royal Botanic Gardens, Richmond, United Kingdom
| | - Karen Martinez-Swatson
- Natural History Museum of Denmark, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Gustavo Hassemer
- Natural History Museum of Denmark, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Department of Botany, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Luís A. Funez
- Department of Botany, Federal University of Santa Catarina, Florianópolis, Brazil
| | - Henrik T. Simonsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Marnix H. Medema
- Bioinformatics Group, Department of Plant Sciences, Wageningen University & Research, Wageningen, Netherlands
| | - Dan Staerk
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Paola Lovato
- Front End Innovation, LEO Pharma A/S, Ballerup, Denmark
| | - Pieter C. Dorrestein
- Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, United States
- Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA, United States
| | - Nina Rønsted
- Natural History Museum of Denmark, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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10
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Yang Y, Morden CW, Sporck‐Koehler MJ, Sack L, Wagner WL, Berry PE. Repeated range expansion and niche shift in a volcanic hotspot archipelago: Radiation of C 4 Hawaiian Euphorbia subgenus Chamaesyce (Euphorbiaceae). Ecol Evol 2018; 8:8523-8536. [PMID: 30250720 PMCID: PMC6145001 DOI: 10.1002/ece3.4354] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/09/2017] [Accepted: 10/15/2017] [Indexed: 12/03/2022] Open
Abstract
Woody perennial plants on islands have repeatedly evolved from herbaceous mainland ancestors. Although the majority of species in Euphorbia subgenus Chamaesyce section Anisophyllum (Euphorbiaceae) are small and herbaceous, a clade of 16 woody species diversified on the Hawaiian Islands. They are found in a broad range of habitats, including the only known C4 plants adapted to wet forest understories. We investigate the history of island colonization and habitat shift in this group. We sampled 153 individuals in 15 of the 16 native species of Hawaiian Euphorbia on six major Hawaiian Islands, plus 11 New World close relatives, to elucidate the biogeographic movement of this lineage within the Hawaiian island chain. We used a concatenated chloroplast DNA data set of more than eight kilobases in aligned length and applied maximum likelihood and Bayesian inference for phylogenetic reconstruction. Age and phylogeographic patterns were co-estimated using BEAST. In addition, we used nuclear ribosomal ITS and the low-copy genes LEAFY and G3pdhC to investigate the reticulate relationships within this radiation. Hawaiian Euphorbia first arrived on Kaua`i or Ni`ihau ca. 5 million years ago and subsequently diverged into 16 named species with extensive reticulation. During this process Hawaiian Euphorbia dispersed from older to younger islands through open vegetation that is disturbance-prone. Species that occur under closed vegetation evolved in situ from open vegetation of the same island and are only found on the two oldest islands of Kaua`i and O`ahu. The biogeographic history of Hawaiian Euphorbia supports a progression rule with within-island shifts from open to closed vegetation.
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Affiliation(s)
- Ya Yang
- Department of Ecology and Evolutionary BiologyUniversity of Michigan, Ann ArborAnn ArborMichigan
- Present address:
Department of Plant and Microbial BiologyUniversity of Minnesota–Twin CitiesFalcon HeightsMinnesotaUSA
| | | | - Margaret J. Sporck‐Koehler
- Department of BotanyUniversity of Hawai`i at MānoaHonoluluHawai`i
- Division of Forestry & WildlifeDepartment of Land and Natural ResourcesHonoluluState of Hawai`i
| | - Lawren Sack
- Department of Ecology and Evolutionary BiologyUniversity of California, Los AngelesLos AngelesCalifornia
| | | | - Paul E. Berry
- Department of Ecology and Evolutionary BiologyUniversity of Michigan, Ann ArborAnn ArborMichigan
- Department of Ecology and Evolutionary BiologyUniversity of Michigan HerbariumAnn ArborMichigan
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11
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Some like it hot: the physiological ecology of C 4 plant evolution. Oecologia 2018; 187:941-966. [PMID: 29955992 DOI: 10.1007/s00442-018-4191-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 06/05/2018] [Indexed: 10/28/2022]
Abstract
The evolution of C4 photosynthesis requires an intermediate phase where photorespiratory glycine produced in the mesophyll cells must flow to the vascular sheath cells for metabolism by glycine decarboxylase. This glycine flux concentrates photorespired CO2 within the sheath cells, allowing it to be efficiently refixed by sheath Rubisco. A modest C4 biochemical cycle is then upregulated, possibly to support the refixation of photorespired ammonia in sheath cells, with subsequent increases in C4 metabolism providing incremental benefits until an optimized C4 pathway is established. 'Why' C4 photosynthesis evolved is largely explained by ancestral C3 species exploiting photorespiratory CO2 to improve carbon gain and thus enhance fitness. While photorespiration depresses C3 performance, it produces a resource (photorespired CO2) that can be exploited to build an evolutionary bridge to C4 photosynthesis. 'Where' C4 evolved is indicated by the habitat of species branching near C3-to-C4 transitions on phylogenetic trees. Consistent with the photorespiratory bridge hypothesis, transitional species show that the large majority of > 60 C4 lineages arose in hot, dry, and/or saline regions where photorespiratory potential is high. 'When' C4 evolved has been clarified by molecular clock analyses using phylogenetic data, coupled with isotopic signatures from fossils. Nearly all C4 lineages arose after 25 Ma when atmospheric CO2 levels had fallen to near current values. This reduction in CO2, coupled with persistent high temperature at low-to-mid-latitudes, met a precondition where photorespiration was elevated, thus facilitating the evolutionary selection pressure that led to C4 photosynthesis.
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12
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Yang Y, Moore MJ, Brockington SF, Mikenas J, Olivieri J, Walker JF, Smith SA. Improved transcriptome sampling pinpoints 26 ancient and more recent polyploidy events in Caryophyllales, including two allopolyploidy events. THE NEW PHYTOLOGIST 2018; 217:855-870. [PMID: 28944472 DOI: 10.1111/nph.14812] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/09/2017] [Indexed: 05/14/2023]
Abstract
Studies of the macroevolutionary legacy of polyploidy are limited by an incomplete sampling of these events across the tree of life. To better locate and understand these events, we need comprehensive taxonomic sampling as well as homology inference methods that accurately reconstruct the frequency and location of gene duplications. We assembled a data set of transcriptomes and genomes from 168 species in Caryophyllales, of which 43 transcriptomes were newly generated for this study, representing one of the most densely sampled genomic-scale data sets available. We carried out phylogenomic analyses using a modified phylome strategy to reconstruct the species tree. We mapped the phylogenetic distribution of polyploidy events by both tree-based and distance-based methods, and explicitly tested scenarios for allopolyploidy. We identified 26 ancient and more recent polyploidy events distributed throughout Caryophyllales. Two of these events were inferred to be allopolyploidy. Through dense phylogenomic sampling, we show the propensity of polyploidy throughout the evolutionary history of Caryophyllales. We also provide a framework for utilizing transcriptome data to detect allopolyploidy, which is important as it may have different macroevolutionary implications compared with autopolyploidy.
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Affiliation(s)
- Ya Yang
- Department of Ecology & Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA
| | - Michael J Moore
- Department of Biology, Oberlin College, 119 Woodland St, Oberlin, OH, 44074-1097, USA
| | | | - Jessica Mikenas
- Department of Biology, Oberlin College, 119 Woodland St, Oberlin, OH, 44074-1097, USA
| | - Julia Olivieri
- Department of Biology, Oberlin College, 119 Woodland St, Oberlin, OH, 44074-1097, USA
| | - Joseph F Walker
- Department of Ecology & Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA
| | - Stephen A Smith
- Department of Ecology & Evolutionary Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI, 48109-1048, USA
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13
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Tian X, Wang Q, Zhou Y. Euphorbia Section Hainanensis (Euphorbiaceae), a New Section Endemic to the Hainan Island of China From Biogeographical, Karyological, and Phenotypical Evidence. FRONTIERS IN PLANT SCIENCE 2018; 9:660. [PMID: 29868103 PMCID: PMC5968112 DOI: 10.3389/fpls.2018.00660] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 04/30/2018] [Indexed: 05/18/2023]
Abstract
Euphorbia hainanensis is an endangered species endemic to the tropical Hainan Island in southern China and of historical importance for Chinese medicine. It is currently the only unplaced species of the genus Euphorbia (Euphorbiaceae) due to its isolated island distribution and debated placement by a previous molecular phylogenetic study. We sequenced nuclear ITS and chloroplast rbcL and ndhF for newly collected accessions of E. hainanensis and additional Euphorbia species found in Hainan, and analyzed the sequences in the context of the entire genus together with published data. All gene regions highly supported that E. hainanensis occupied an isolated phylogenetic position, showing no close affinity with any known Euphorbia sections suggesting it was a new section. ITS placed E. hainanensis sister to sect. Crossadenia (subgenus Chamaesyce) from Brazil with an estimated divergence time of 9.3-30.6 Mya while the chloroplast markers placed E. hainanensis at a position sister to the entire New World clade of Euphorbia subgenus Chamaesyce. In addition, our karyological results suggested a close affinity between E. hainanensis and the New World species of Euphorbia subg. Chamaesyce, with which shared the same chromosome number 2n = 28 and basic chromosome number x = 7. Phenotypically, E. hainanensis is unique with no close resemblance to other species in Euphorbia subg. Chamaesyce. Based on its isolated biogeographical, karyological, and phenotypical position, we propose a new section E. subgenus Chamaesyce section Hainanensis that might origin from long distance dispersal events because collective evidences showed a close affinity between the species from the Old World with those from the New World.
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Affiliation(s)
- Xinmin Tian
- Department of Biological Sciences, College of Life Science and Technology, Xinjiang University, Urumqi, China
- *Correspondence: Xinmin Tian
| | - Qiuyan Wang
- Key Laboratory of Oasis Ecology, Ministry of Education, Institute of Arid Ecology and Environment, Xinjiang University, Urumqi, China
| | - Yongfeng Zhou
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, CA, United States
- School of Life Science, Lanzhou University, Lanzhou, China
- Yongfeng Zhou
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14
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Kadereit G, Bohley K, Lauterbach M, Tefarikis DT, Kadereit JW. C 3 -C 4 intermediates may be of hybrid origin - a reminder. THE NEW PHYTOLOGIST 2017; 215:70-76. [PMID: 28397963 DOI: 10.1111/nph.14567] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 03/02/2017] [Indexed: 05/09/2023]
Abstract
The currently favoured model of the evolution of C4 photosynthesis relies heavily on the interpretation of the broad phenotypic range of naturally growing C3 -C4 intermediates as proxies for evolutionary intermediate steps. On the other hand, C3 -C4 intermediates had earlier been interpreted as hybrids or hybrid derivates. By first comparing experimentally generated with naturally growing C3 -C4 intermediates, and second summarising either direct or circumstantial evidence for hybridisation in lineages comprising C3 , C4 and C3 -C4 intermediates, we conclude that a possible hybrid origin of C3 -C4 intermediates deserves careful examination. While we acknowledge that the current model of C4 photosynthesis evolution is clearly the best available, C3 -C4 intermediates of hybrid origin, if existing, should not be used for further analysis of this model. However, experimental C3 × C4 hybrids potentially are excellent systems to analyse the genetic differences between C3 and C4 species and, also using segregating progeny, to study the relationship between individual photosynthetic traits and environmental factors.
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Affiliation(s)
- Gudrun Kadereit
- Institut für Molekulare Physiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Katharina Bohley
- Institut für Molekulare Physiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Maximilian Lauterbach
- Institut für Molekulare Physiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Delphine T Tefarikis
- Institut für Molekulare Physiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Joachim W Kadereit
- Institut für Organismische und Molekulare Evolutionsbiologie, Johannes Gutenberg-Universität Mainz, Mainz, Germany
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15
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Sage RF. A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame. JOURNAL OF EXPERIMENTAL BOTANY 2017; 68:4039-4056. [PMID: 28110278 DOI: 10.1093/jxb/erx005] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Fifty years ago, the C4 photosynthetic pathway was first characterized. In the subsequent five decades, much has been learned about C4 plants, such that it is now possible to place nearly all C4 species into their respective evolutionary lineages. Sixty-one independent lineages of C4 photosynthesis are identified, with additional, ancillary C4 origins possible in 12 of these principal lineages. The lineages produced ~8100 C4 species (5044 grasses, 1322 sedges, and 1777 eudicots). Using midpoints of stem and crown node dates in their respective phylogenies, the oldest and most speciose C4 lineage is the grass lineage Chloridoideae, estimated to be near 30 million years old. Most C4 lineages are estimated to be younger than 15 million years. Older C4 lineages tend to be more speciose, while those younger than 7 million years have <43 species each. To further highlight C4 photosynthesis for a 50th anniversary snapshot, a Hall of Fame comprised of the 40 most significant C4 species is presented. Over the next 50 years, preservation of the Earth's C4 diversity is a concern, largely because of habitat loss due to elevated CO2 effects, invasive species, and expanded agricultural activities. Ironically, some members of the C4 Hall of Fame are leading threats to the natural C4 flora due to their association with human activities on landscapes where most C4 plants occur.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5R3C6
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16
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Sage RF, Sultmanis S. Why are there no C 4 forests? JOURNAL OF PLANT PHYSIOLOGY 2016; 203:55-68. [PMID: 27481816 DOI: 10.1016/j.jplph.2016.06.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 06/13/2016] [Accepted: 06/15/2016] [Indexed: 05/22/2023]
Abstract
C4 photosynthesis is absent from the arborescent life form, with the exception of seven Hawaiian Euphorbia species and a few desert shrubs that become arborescent with age. As a consequence, wherever C3 trees can establish, their height advantage enables them to outcompete low stature C4 vegetation. Had C4 photosynthesis been able to evolve in an arborescent life form, forest cover (by C4 trees) could have been much more extensive than today, with significant consequences for the biosphere. Here, we address why there are so few C4 trees. Physiological explanations associated with low light performance of C4 photosynthesis are not supported, because C4 shade-tolerant species exhibit similar performance as shade-tolerant C3 species in terms of quantum yield, steady-state photosynthetic and use of sunflecks. Hence, hypothetical C4 trees could occur in the regeneration niche of forests. Constraints associated with the evolutionary history of the C4 lineages are more plausible. Most C4 species are grasses and sedges, which lack meristems needed for arborescence, while most C4 eudicots are highly specialized for harsh (arid, saline, hot) or disturbed habitats where arborescence may be maladapted. Most C4 eudicot clades are also young, and have not had sufficient time to radiate beyond the extreme environments where C4 evolution is favored. In the case of the Hawaiian Euphorbia species, they belong to one of the oldest and most diverse C4 lineages, which primed this group to evolve arborescence in a low-competition environment that appeared on the remote Hawaiian Islands.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S3B2, Canada.
| | - Stefanie Sultmanis
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S3B2, Canada
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17
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Sage RF. A portrait of the C4 photosynthetic family on the 50th anniversary of its discovery: species number, evolutionary lineages, and Hall of Fame. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:4039-56. [PMID: 27053721 DOI: 10.1093/jxb/erw156] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Fifty years ago, the C4 photosynthetic pathway was first characterized. In the subsequent five decades, much has been learned about C4 plants, such that it is now possible to place nearly all C4 species into their respective evolutionary lineages. Sixty-one independent lineages of C4 photosynthesis are identified, with additional, ancillary C4 origins possible in 12 of these principal lineages. The lineages produced ~8100 C4 species (5044 grasses, 1322 sedges, and 1777 eudicots). Using midpoints of stem and crown node dates in their respective phylogenies, the oldest and most speciose C4 lineage is the grass lineage Chloridoideae, estimated to be near 30 million years old. Most C4 lineages are estimated to be younger than 15 million years. Older C4 lineages tend to be more speciose, while those younger than 7 million years have <43 species each. To further highlight C4 photosynthesis for a 50th anniversary snapshot, a Hall of Fame comprised of the 40 most significant C4 species is presented. Over the next 50 years, preservation of the Earth's C4 diversity is a concern, largely because of habitat loss due to elevated CO2 effects, invasive species, and expanded agricultural activities. Ironically, some members of the C4 Hall of Fame are leading threats to the natural C4 flora due to their association with human activities on landscapes where most C4 plants occur.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5R3C6
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18
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Sokoloff PC, Freebury CE, Hamilton PB, Saarela JM. The "Martian" flora: new collections of vascular plants, lichens, fungi, algae, and cyanobacteria from the Mars Desert Research Station, Utah. Biodivers Data J 2016:e8176. [PMID: 27350765 PMCID: PMC4911540 DOI: 10.3897/bdj.4.e8176] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 06/03/2016] [Indexed: 11/12/2022] Open
Abstract
The Mars Desert Research Station is a Mars analog research site located in the desert outside of Hanksville, Utah, U.S.A. Here we present a preliminary checklist of the vascular plant and lichen flora for the station, based on collections made primarily during a two-week simulated Mars mission in November, 2014. Additionally, we present notes on the endolithic chlorophytes and cyanobacteria, and the identification of a fungal genus also based on these collections. Altogether, we recorded 38 vascular plant species from 14 families, 13 lichen species from seven families, six algae taxa including both chlorophytes and cyanobacteria, and one fungal genus from the station and surrounding area. We discuss this floristic diversity in the context of the ecology of the nearby San Rafael Swell and the desert areas of Wayne and Emery counties in southeastern Utah.
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19
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Santana KCB, Pinangé DSB, Vasconcelos S, Oliveira AR, Brasileiro-Vidal AC, Alves MV, Benko-Iseppon AM. Unraveling the karyotype structure of the spurges Euphorbia hirta Linnaeus, 1753 and E. hyssopifolia Linnaeus, 1753 (Euphorbiaceae) using genome size estimation and heterochromatin differentiation. COMPARATIVE CYTOGENETICS 2016; 10:657-669. [PMID: 28123686 PMCID: PMC5240516 DOI: 10.3897/compcytogen.v10i4.8193] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 04/23/2016] [Indexed: 05/09/2023]
Abstract
Euphorbia Linnaeus, 1753 (Euphorbiaceae) is one of the most diverse and complex genera among the angiosperms, showing a huge diversity in morphologic traits and ecologic patterns. In order to improve the knowledge of the karyotype organization of Euphorbia hirta (2n = 18) and Euphorbia hyssopifolia (2n = 12), cytogenetic studies were performed by means of conventional staining with Giemsa, genome size estimations with flow cytometry, heterochromatin differentiation with chromomycin A3 (CMA) and 4',6-diamidino-2-phenylindole (DAPI) and Giemsa C-banding, fluorescent in situ hybridization (FISH) with 45S and 5S rDNA probes, and impregnation with silver nitrate (AgNO3). Our results revealed small metacentric chromosomes, CMA+/DAPI0 heterochromatin in the pericentromeric regions of all chromosomes and CMA+/DAPI- in the distal part of chromosome arms carriers of nucleolar organizing regions (NORs). The DNA content measurements revealed small genomes for both species: Euphorbia hirta with 2C = 0.77 pg and Euphorbia hyssopifolia with 2C = 1.41 pg. After FISH procedures, Euphorbia hirta, and Euphorbia hyssopifolia presented three and four pairs of terminal 45S rDNA sites, respectively, colocalizing with CMA+ heterochromatic blocks, besides only one interstitial pair of 5S rDNA signals. Additionally, the maximum number of active NORs agreed with the total number of observed 45S rDNA sites. This work represents the first analysis using FISH in the subfamily Euphorbioideae, revealing a significant number of chromosomal markers, which may be very helpful to understand evolutionary patterns among Euphorbia species.
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Affiliation(s)
- Karla C. B. Santana
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil
| | - Diego S. B. Pinangé
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil
- Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Rua Prof. Nelson Chaves s/n, CEP 50670-901 Recife, PE, Brazil
| | - Santelmo Vasconcelos
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil
- Department of Sustainable Development, Vale Institute of Technology, Rua Boaventura da Silva, 955, Umarizal, CEP 66055-090, Belém, PA, Brazil
| | - Ana R. Oliveira
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil
| | - Ana C. Brasileiro-Vidal
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil
| | - Marccus V. Alves
- Departamento de Botânica, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Rua Prof. Nelson Chaves s/n, CEP 50670-901 Recife, PE, Brazil
| | - Ana M. Benko-Iseppon
- Departamento de Genética, Centro de Ciências Biológicas, Universidade Federal de Pernambuco, Av. da Engenharia s/n, CEP 50740-600 Recife, PE, Brazil
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20
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Giner JL, Schroeder TN. Polygonifoliol, a New Tirucallane Triterpene from the Latex of the Seaside SandmatEuphorbia polygonifolia. Chem Biodivers 2015; 12:1126-9. [DOI: 10.1002/cbdv.201400426] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Indexed: 11/08/2022]
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21
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Winter K, Holtum JAM. Cryptic crassulacean acid metabolism (CAM) in Jatropha curcas. FUNCTIONAL PLANT BIOLOGY : FPB 2015; 42:711-717. [PMID: 32480714 DOI: 10.1071/fp15021] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/13/2015] [Indexed: 06/11/2023]
Abstract
Jatropha curcas L. is a drought-tolerant shrub or small tree that is a candidate bioenergy feedstock. It is a member of the family Euphorbiaceae in which both CAM and C4 photosynthesis have evolved. Here, we report that J. curcas exhibits features diagnostic of low-level CAM. Small increases in nocturnal acid content were consistently observed in photosynthetic stems and occasionally in leaves. Acidification was associated with transient contractions in CO2 loss at night rather than with net CO2 dark fixation. Although the CAM-type nocturnal CO2 uptake signal was masked by background respiration, estimates of dark CO2 fixation based upon the 2:1 stoichiometric relationship between H+ accumulated and CO2 fixed indicated substantial carbon retention in the stems via the CAM cycle. It is proposed that under conditions of drought, low-level CAM in J. curcas stems serves primarily to conserve carbon rather than water.
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Affiliation(s)
- Klaus Winter
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panama
| | - Joseph A M Holtum
- Smithsonian Tropical Research Institute, PO Box 0843-03092, Balboa, Ancón, Republic of Panama
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22
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Sage RF, Stata M. Photosynthetic diversity meets biodiversity: the C4 plant example. JOURNAL OF PLANT PHYSIOLOGY 2015; 172:104-19. [PMID: 25264020 DOI: 10.1016/j.jplph.2014.07.024] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Revised: 07/02/2014] [Accepted: 07/02/2014] [Indexed: 05/16/2023]
Abstract
Physiological diversification reflects adaptation for specific environmental challenges. As the major physiological process that provides plants with carbon and energy, photosynthesis is under strong evolutionary selection that gives rise to variability in nearly all parts of the photosynthetic apparatus. Here, we discuss how plants, notably those using C4 photosynthesis, diversified in response to environmental challenges imposed by declining atmospheric CO2 content in recent geological time. This reduction in atmospheric CO2 increases the rate of photorespiration and reduces photosynthetic efficiency. While plants have evolved numerous mechanisms to compensate for low CO2, the most effective are the carbon concentration mechanisms of C4, C2, and CAM photosynthesis; and the pumping of dissolved inorganic carbon, mainly by algae. C4 photosynthesis enables plants to dominate warm, dry and often salinized habitats, and to colonize areas that are too stressful for most plant groups. Because C4 lineages generally lack arborescence, they cannot form forests. Hence, where they predominate, C4 plants create a different landscape than would occur if C3 plants were to predominate. These landscapes (mostly grasslands and savannahs) present unique selection environments that promoted the diversification of animal guilds able to graze upon the C4 vegetation. Thus, the rise of C4 photosynthesis has made a significant contribution to the origin of numerous biomes in the modern biosphere.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, Canada M5S3B2.
| | - Matt Stata
- Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, Canada M5S3B2
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23
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Baldwin BG. Origins of Plant Diversity in the California Floristic Province. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2014. [DOI: 10.1146/annurev-ecolsys-110512-135847] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent biogeographic and evolutionary studies have led to improved understanding of the origins of exceptionally high plant diversity in the California Floristic Province (CA-FP). Spatial analyses of Californian plant diversity and endemism reinforce the importance of geographically isolated areas of high topographic and edaphic complexity as floristic hot spots, in which the relative influence of factors promoting evolutionary divergence and buffering of lineages against extinction has gained increased attention. Molecular phylogenetic studies spanning the flora indicate that immediate sources of CA-FP lineages bearing endemic species diversity have been mostly within North America—especially within the west and southwest—even for groups of north temperate affinity, and that most diversification of extant lineages in the CA-FP has occurred since the mid-Miocene, with the transition toward summer-drying. Process-focused studies continue to implicate environmental heterogeneity at local or broad geographic scales in evolutionary divergence within the CA-FP, often associated with reproductive or life-history shifts or sometimes hybridization.
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Affiliation(s)
- Bruce G. Baldwin
- Jepson Herbarium and Department of Integrative Biology, University of California, Berkeley, California 94720-2465
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Horn JW, Xi Z, Riina R, Peirson JA, Yang Y, Dorsey BL, Berry PE, Davis CC, Wurdack KJ. Evolutionary bursts inEuphorbia(Euphorbiaceae) are linked with photosynthetic pathway. Evolution 2014; 68:3485-504. [DOI: 10.1111/evo.12534] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 09/17/2014] [Indexed: 12/29/2022]
Affiliation(s)
- James W. Horn
- Department of Botany; Smithsonian Institution; NMNH MRC-166, P.O. Box 37012 Washington DC 20013
| | - Zhenxiang Xi
- Department of Organismic and Evolutionary Biology; Harvard University Herbaria; 22 Divinity Avenue Cambridge Massachusetts 02138
| | - Ricarda Riina
- Department of Ecology and Evolutionary Biology and University of Michigan Herbarium; 3600 Varsity Drive Ann Arbor Michigan 48108
- Real Jardín Botánico; RJB-CSIC; Plaza de Murillo 2 28014 Madrid Spain
| | - Jess A. Peirson
- Department of Ecology and Evolutionary Biology and University of Michigan Herbarium; 3600 Varsity Drive Ann Arbor Michigan 48108
| | - Ya Yang
- Department of Ecology and Evolutionary Biology and University of Michigan Herbarium; 3600 Varsity Drive Ann Arbor Michigan 48108
| | - Brian L. Dorsey
- Department of Ecology and Evolutionary Biology and University of Michigan Herbarium; 3600 Varsity Drive Ann Arbor Michigan 48108
- The Huntington Botanical Gardens; 1151 Oxford Road San Marino California 91108
| | - Paul E. Berry
- Department of Ecology and Evolutionary Biology and University of Michigan Herbarium; 3600 Varsity Drive Ann Arbor Michigan 48108
| | - Charles C. Davis
- Department of Organismic and Evolutionary Biology; Harvard University Herbaria; 22 Divinity Avenue Cambridge Massachusetts 02138
| | - Kenneth J. Wurdack
- Department of Botany; Smithsonian Institution; NMNH MRC-166, P.O. Box 37012 Washington DC 20013
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25
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Stata M, Sage TL, Rennie TD, Khoshravesh R, Sultmanis S, Khaikin Y, Ludwig M, Sage RF. Mesophyll cells of C4 plants have fewer chloroplasts than those of closely related C3 plants. PLANT, CELL & ENVIRONMENT 2014; 37:2587-2600. [PMID: 24689501 DOI: 10.1111/pce.12331] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 03/03/2014] [Accepted: 03/17/2014] [Indexed: 06/03/2023]
Abstract
The evolution of C(4) photosynthesis from C(3) ancestors eliminates ribulose bisphosphate carboxylation in the mesophyll (M) cell chloroplast while activating phosphoenolpyruvate (PEP) carboxylation in the cytosol. These changes may lead to fewer chloroplasts and different chloroplast positioning within M cells. To evaluate these possibilities, we compared chloroplast number, size and position in M cells of closely related C(3), C(3) -C(4) intermediate and C(4) species from 12 lineages of C(4) evolution. All C(3) species had more chloroplasts per M cell area than their C(4) relatives in high-light growth conditions. C(3) species also had higher chloroplast coverage of the M cell periphery than C(4) species, particularly opposite intercellular air spaces. In M cells from 10 of the 12 C(4) lineages, a greater fraction of the chloroplast envelope was pulled away from the plasmalemma in the C(4) species than their C(3) relatives. C(3) -C(4) intermediate species generally exhibited similar patterns as their C(3) relatives. We interpret these results to reflect adaptive shifts that facilitate efficient C(4) function by enhancing diffusive access to the site of primary carbon fixation in the cytosol. Fewer chloroplasts in C(4) M cells would also reduce shading of the bundle sheath chloroplasts, which also generate energy required by C(4) photosynthesis.
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Affiliation(s)
- Matt Stata
- Department of Ecology and Evolutionary Biology, The University of Toronto, Toronto, ON, Canada, M5S 3B2
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26
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Sage RF, Khoshravesh R, Sage TL. From proto-Kranz to C4 Kranz: building the bridge to C4 photosynthesis. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:3341-56. [PMID: 24803502 DOI: 10.1093/jxb/eru180] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In this review, we examine how the specialized "Kranz" anatomy of C4 photosynthesis evolved from C3 ancestors. Kranz anatomy refers to the wreath-like structural traits that compartmentalize the biochemistry of C4 photosynthesis and enables the concentration of CO2 around Rubisco. A simplified version of Kranz anatomy is also present in the species that utilize C2 photosynthesis, where a photorespiratory glycine shuttle concentrates CO2 into an inner bundle-sheath-like compartment surrounding the vascular tissue. C2 Kranz is considered to be an intermediate stage in the evolutionary development of C4 Kranz, based on the intermediate branching position of C2 species in 14 evolutionary lineages of C4 photosynthesis. In the best-supported model of C4 evolution, Kranz anatomy in C2 species evolved from C3 ancestors with enlarged bundle sheath cells and high vein density. Four independent lineages have been identified where C3 sister species of C2 plants exhibit an increase in organelle numbers in the bundle sheath and enlarged bundle sheath cells. Notably, in all of these species, there is a pronounced shift of mitochondria to the inner bundle sheath wall, forming an incipient version of the C2 type of Kranz anatomy. This incipient version of C2 Kranz anatomy is termed proto-Kranz, and is proposed to scavenge photorespiratory CO2. By doing so, it may provide fitness benefits in hot environments, and thus represent a critical first stage of the evolution of both the C2 and C4 forms of Kranz anatomy.
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Affiliation(s)
- Rowan F Sage
- Department of Ecology and Evolutionary Biology, The University of Toronto, 25 Willcocks Street, Toronto, On M5S3B2 Canada
| | - Roxana Khoshravesh
- Department of Ecology and Evolutionary Biology, The University of Toronto, 25 Willcocks Street, Toronto, On M5S3B2 Canada
| | - Tammy L Sage
- Department of Ecology and Evolutionary Biology, The University of Toronto, 25 Willcocks Street, Toronto, On M5S3B2 Canada
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27
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Gere J, Yessoufou K, Daru BH, Mankga LT, Maurin O, van der Bank M. Incorporating trnH-psbA to the core DNA barcodes improves significantly species discrimination within southern African Combretaceae. Zookeys 2013; 365:129-47. [PMID: 24453555 PMCID: PMC3890675 DOI: 10.3897/zookeys.365.5728] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Accepted: 09/13/2013] [Indexed: 11/19/2022] Open
Abstract
Recent studies indicate that the discriminatory power of the core DNA barcodes (rbcLa + matK) for land plants may have been overestimated since their performance have been tested only on few closely related species. In this study we focused mainly on how the addition of complementary barcodes (nrITS and trnH-psbA) to the core barcodes will affect the performance of the core barcodes in discriminating closely related species from family to section levels. In general, we found that the core barcodes performed poorly compared to the various combinations tested. Using multiple criteria, we finally advocated for the use of the core + trnH-psbA as potential DNA barcode for the family Combretaceae at least in southern Africa. Our results also indicate that the success of DNA barcoding in discriminating closely related species may be related to evolutionary and possibly the biogeographic histories of the taxonomic group tested.
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Affiliation(s)
- Jephris Gere
- African Centre for DNA Barcoding, Department of Botany & Plant Biotechnology, University of Johannesburg, PO Box 524, South Africa
| | - Kowiyou Yessoufou
- African Centre for DNA Barcoding, Department of Botany & Plant Biotechnology, University of Johannesburg, PO Box 524, South Africa
- C4 EcoSolutions, 9 Mohr Road Tokai, Cape Town, South Africa 7945
| | - Barnabas H. Daru
- African Centre for DNA Barcoding, Department of Botany & Plant Biotechnology, University of Johannesburg, PO Box 524, South Africa
| | - Ledile T. Mankga
- African Centre for DNA Barcoding, Department of Botany & Plant Biotechnology, University of Johannesburg, PO Box 524, South Africa
| | - Olivier Maurin
- African Centre for DNA Barcoding, Department of Botany & Plant Biotechnology, University of Johannesburg, PO Box 524, South Africa
| | - Michelle van der Bank
- African Centre for DNA Barcoding, Department of Botany & Plant Biotechnology, University of Johannesburg, PO Box 524, South Africa
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28
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Roy T, Chang TH, Lan T, Lindqvist C. Phylogeny and biogeography of New World Stachydeae (Lamiaceae) with emphasis on the origin and diversification of Hawaiian and South American taxa. Mol Phylogenet Evol 2013; 69:218-38. [DOI: 10.1016/j.ympev.2013.05.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 05/25/2013] [Accepted: 05/30/2013] [Indexed: 12/15/2022]
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29
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Aubriot X, Lowry PP, Cruaud C, Couloux A, Haevermans T. DNA
barcoding in a biodiversity hot spot: potential value for the identification of
M
alagasy
E
uphorbia
L. listed in
CITES A
ppendices I and
II. Mol Ecol Resour 2012; 13:57-65. [DOI: 10.1111/1755-0998.12028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 07/06/2012] [Accepted: 07/17/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Xavier Aubriot
- Muséum national d'histoire naturelle Département Systématique et Evolution UMR 7205 MNHN/CNRS Origine Structure et Evolution de la Biodiversité (OSEB) Herbier Plantes Vasculaires CP 39, 57 rue Cuvier 75231 Paris CEDEX 05 France
| | - Porter P. Lowry
- Muséum national d'histoire naturelle Département Systématique et Evolution UMR 7205 MNHN/CNRS Origine Structure et Evolution de la Biodiversité (OSEB) Herbier Plantes Vasculaires CP 39, 57 rue Cuvier 75231 Paris CEDEX 05 France
- Missouri Botanical Garden PO Box 299 St. Louis MO 63166–0299 USA
| | - Corinne Cruaud
- Genoscope Centre National de Séquençage CP 5706, 2 rue Gaston Crémieux 91057 Evry CEDEX France
| | - Arnaud Couloux
- Genoscope Centre National de Séquençage CP 5706, 2 rue Gaston Crémieux 91057 Evry CEDEX France
| | - Thomas Haevermans
- Muséum national d'histoire naturelle Département Systématique et Evolution UMR 7205 MNHN/CNRS Origine Structure et Evolution de la Biodiversité (OSEB) Herbier Plantes Vasculaires CP 39, 57 rue Cuvier 75231 Paris CEDEX 05 France
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30
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Kadereit G, Ackerly D, Pirie MD. A broader model for C₄ photosynthesis evolution in plants inferred from the goosefoot family (Chenopodiaceae s.s.). Proc Biol Sci 2012; 279:3304-11. [PMID: 22628474 PMCID: PMC3385724 DOI: 10.1098/rspb.2012.0440] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Accepted: 05/01/2012] [Indexed: 11/12/2022] Open
Abstract
C(4) photosynthesis is a fascinating example of parallel evolution of a complex trait involving multiple genetic, biochemical and anatomical changes. It is seen as an adaptation to deleteriously high levels of photorespiration. The current scenario for C(4) evolution inferred from grasses is that it originated subsequent to the Oligocene decline in CO(2) levels, is promoted in open habitats, acts as a pre-adaptation to drought resistance, and, once gained, is not subsequently lost. We test the generality of these hypotheses using a dated phylogeny of Amaranthaceae s.l. (including Chenopodiaceae), which includes the largest number of C(4) lineages in eudicots. The oldest chenopod C(4) lineage dates back to the Eocene/Oligocene boundary, representing one of the first origins of C(4) in plants, but still corresponding with the Oligocene decline of atmospheric CO(2). In contrast to grasses, the rate of transitions from C(3) to C(4) is highest in ancestrally drought resistant (salt-tolerant and succulent) lineages, implying that adaptation to dry or saline habitats promoted the evolution of C(4); and possible reversions from C(4) to C(3) are apparent. We conclude that the paradigm established in grasses must be regarded as just one aspect of a more complex system of C(4) evolution in plants in general.
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Affiliation(s)
- Gudrun Kadereit
- Institut für Allgemeine Botanik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany.
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31
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Horn JW, van Ee BW, Morawetz JJ, Riina R, Steinmann VW, Berry PE, Wurdack KJ. Phylogenetics and the evolution of major structural characters in the giant genus Euphorbia L. (Euphorbiaceae). Mol Phylogenet Evol 2012; 63:305-26. [PMID: 22273597 DOI: 10.1016/j.ympev.2011.12.022] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 11/17/2011] [Accepted: 12/28/2011] [Indexed: 11/27/2022]
Abstract
Euphorbia is among the largest genera of angiosperms, with about 2000 species that are renowned for their remarkably diverse growth forms. To clarify phylogenetic relationships in the genus, we used maximum likelihood, bayesian, and parsimony analyses of DNA sequence data from 10 markers representing all three plant genomes, averaging more than 16kbp for each accession. Taxon sampling included 176 representatives from Euphorbioideae (including 161 of Euphorbia). Analyses of these data robustly resolve a backbone topology of four major, subgeneric clades--Esula, Rhizanthium, Euphorbia, and Chamaesyce--that are successively sister lineages. Ancestral state reconstructions of six reproductive and growth form characters indicate that the earliest Euphorbia species were likely woody, non-succulent plants with helically arranged leaves and 5-glanded cyathia in terminal inflorescences. The highly modified growth forms and reproductive features in Euphorbia have independent origins within the subgeneric clades. Examples of extreme parallelism in trait evolution include at least 14 origins of xeromorphic growth forms and at least 13 origins of seed caruncles. The evolution of growth form and inflorescence position are significantly correlated, and a pathway of evolutionary transitions is supported that has implications for the evolution of Euphorbia xerophytes of large stature. Such xerophytes total more than 400 species and are dominants of vegetation types throughout much of arid Africa and Madagascar.
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Affiliation(s)
- James W Horn
- Department of Botany, Smithsonian Institution, NMNH MRC-166, P.O. Box 37012, Washington, DC 20013-7012, USA
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