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Harchouni S, England S, Vieu J, Romand S, Aouane A, Citerne S, Legeret B, Alric J, Li-Beisson Y, Menand B, Field B. Guanosine tetraphosphate (ppGpp) accumulation inhibits chloroplast gene expression and promotes super grana formation in the moss Physcomitrium (Physcomitrella) patens. New Phytol 2022; 236:86-98. [PMID: 35715975 DOI: 10.1111/nph.18320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
The nucleotides guanosine tetraphosphate and pentaphosphate (or (p)ppGpp) are implicated in the regulation of chloroplast function in plants. (p)ppGpp signalling is best understood in the model vascular plant Arabidopsis thaliana in which it acts to regulate plastid gene expression to influence photosynthesis, plant development and immunity. However, little information is known about the conservation or diversity of (p)ppGpp signalling in other land plants. We studied the function of ppGpp in the moss Physcomitrium (previously Physcomitrella) patens using an inducible system for triggering ppGpp accumulation. We used this approach to investigate the effects of ppGpp on chloroplast function, photosynthesis and growth. We demonstrate that ppGpp accumulation causes a dramatic drop in photosynthetic capacity by inhibiting chloroplast gene expression. This was accompanied by the unexpected reorganisation of the thylakoid system into super grana. Surprisingly, these changes did not affect gametophore growth, suggesting that bryophytes and vascular plants may have different tolerances to defects in photosynthesis. Our findings point to the existence of both highly conserved and more specific targets of (p)ppGpp signalling in the land plants that may reflect different growth strategies.
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Affiliation(s)
- Seddik Harchouni
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, 13009, Marseille, France
| | - Samantha England
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, 13009, Marseille, France
| | - Julien Vieu
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, 13009, Marseille, France
| | - Shanna Romand
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, 13009, Marseille, France
| | - Aicha Aouane
- Aix-Marseille Université, CNRS, Institut de Biologie du Developpement de Marseille (IBDM), 13009, Marseille, France
| | - Sylvie Citerne
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, 78000, Versailles, France
| | - Bertrand Legeret
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, CEA Cadarache, Saint-Paul-lez Durance, 13108, France
| | - Jean Alric
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, CEA Cadarache, Saint-Paul-lez Durance, 13108, France
| | - Yonghua Li-Beisson
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, CEA Cadarache, Saint-Paul-lez Durance, 13108, France
| | - Benoît Menand
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, 13009, Marseille, France
| | - Benjamin Field
- Aix-Marseille Université, CEA, CNRS, BIAM, UMR7265, 13009, Marseille, France
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Trunz V, Packer L, Vieu J, Arrigo N, Praz CJ. Comprehensive phylogeny, biogeography and new classification of the diverse bee tribe Megachilini: Can we use DNA barcodes in phylogenies of large genera? Mol Phylogenet Evol 2016; 103:245-259. [PMID: 27400629 DOI: 10.1016/j.ympev.2016.07.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 06/23/2016] [Accepted: 07/07/2016] [Indexed: 11/24/2022]
Abstract
Classification and evolutionary studies of particularly speciose clades pose important challenges, as phylogenetic analyses typically sample a small proportion of the existing diversity. We examine here one of the largest bee genera, the genus Megachile - the dauber and leafcutting bees. Besides presenting a phylogeny based on five nuclear genes (5480 aligned nucleotide positions), we attempt to use the phylogenetic signal of mitochondrial DNA barcodes, which are rapidly accumulating and already include a substantial proportion of the known species diversity in the genus. We used barcodes in two ways: first, to identify particularly divergent lineages and thus to guide taxon sampling in our nuclear phylogeny; second, to augment taxon sampling by combining nuclear markers (as backbone for ancient divergences) with DNA barcodes. Our results indicate that DNA barcodes bear phylogenetic signal limited to very recent divergences (3-4 my before present). Sampling within clades of very closely related species may be augmented using this technique, but our results also suggest statistically supported, but incongruent placements of some taxa. However, the addition of one single nuclear gene (LW-rhodopsin) to the DNA barcode data was enough to recover meaningful placement with high clade support values for nodes up to 15 million years old. We discuss different proposals for the generic classification of the tribe Megachilini. Finding a classification that is both in agreement with our phylogenetic hypotheses and practical in terms of diagnosability is particularly challenging as our analyses recover several well-supported clades that include morphologically heterogeneous lineages. We favour a classification that recognizes seven morphologically well-delimited genera in Megachilini: Coelioxys, Gronoceras, Heriadopsis, Matangapis, Megachile, Noteriades and Radoszkowskiana. Our results also lead to the following classification changes: the groups known as Dinavis, Neglectella, Eurymella and Phaenosarus are reestablished as valid subgenera of the genus Megachile, while the subgenus Alocanthedon is placed in synonymy with M. (Callomegachile), the subgenera Parachalicodoma and Largella with M. (Pseudomegachile), Anodonteutricharaea with M. (Paracella), Platysta with M. (Eurymella), and Grosapis and Eumegachile with M. (Megachile) (new synonymies). In addition, we use maximum likelihood reconstructions of ancestral geographic ranges to infer the origin of the tribe and reconstruct the main dispersal routes explaining the current, cosmopolitan distribution of this genus.
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Affiliation(s)
- V Trunz
- Institute of Biology, University of Neuchatel, Emile-Argand 11, 2000 Neuchatel, Switzerland
| | - L Packer
- Department of Biology, York University, 4700 Keele St., Toronto, ON M3J 1P3, Canada
| | - J Vieu
- Institute of Biology, University of Neuchatel, Emile-Argand 11, 2000 Neuchatel, Switzerland
| | - N Arrigo
- Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland
| | - C J Praz
- Institute of Biology, University of Neuchatel, Emile-Argand 11, 2000 Neuchatel, Switzerland.
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Dauphin B, Vieu J, Grant JR. Molecular phylogenetics supports widespread cryptic species in moonworts (Botrychium s.s., Ophioglossaceae). Am J Bot 2014; 101:128-140. [PMID: 24401328 DOI: 10.3732/ajb.1300154] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
PREMISE OF THE STUDY Previous phylogenetic studies of moonworts (Botrychium sensu stricto (s.s.)) included few taxa from outside of North America. This low geographical representation limited interpretations of relationships of this group rich in cryptic species. With 18 out of 30 species in the genus being polyploid, understanding their evolutionary history remains a major challenge. METHODS A new molecular phylogeny was reconstructed using Maximum Likelihood (ML) and Bayesian Inference (BI) analyses based on multiple accessions of the most wide-ranging Arctic taxa of Botrychium in North America and Europe using three noncoding plastid DNA regions (psbA-trnH(GUG), trnL(UAA)-trnF(GAA) intergenic spacer, and rpL16 intron). KEY RESULTS The new phylogeny confirms the identity of several recently described species and proposed new taxa. Nine subclades are newly identified within the two major clades in Botrychium s.s.: Lanceolatum and Lunaria. Chloroplast DNA was variable enough to separate morphologically cryptic species in the Lunaria clade. On the contrary, much less variation is seen within the morphologically variable Lanceolatum clade despite sampling over the same broad geographic range. The chloroplast region psbA-trnH(GUG) is identified as an efficient DNA barcode for the identification of cryptic taxa in Botrychium s.s. CONCLUSIONS The combined increase in species representation, samples from throughout the geographic range of each species, and sequencing of multiple plastid DNA regions supports morphologically cryptic species in Botrychium s.s.
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Affiliation(s)
- Benjamin Dauphin
- Laboratoire de botanique évolutive, Université de Neuchâtel, rue Emile-Argand 11, 2000 Neuchâtel, Switzerland
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