Putative roles of glutaredoxin-BolA holo-heterodimers in plants
T Dhalleine, N Rouhier, J Couturier. Plant Signaling & Behavior 9 (3), e28564
Category Archives: Academic productions
Article: Physiologia plantarum
Adventitious root formation in tree species: involvement of transcription factors
V Legué, A Rigal, RP Bhalerao. Physiologia Plantarum
Abstract:
Adventitious rooting is an essential step in the vegetative propagation of economically important horticultural and woody species. Populus has emerged as an experimental model for studying processes that are important in tree growth and development. It is highly useful for molecular genetic analysis of adventitious roots in trees. In this short review, we will highlight the recent progress made in the identification of transcription factors involved in the control of adventitious rooting in woody species. Their regulation will be discussed.
Article: Protein & Cell
Characterization of poplar GrxS14 in different structural forms
Published online: 18 March 2014
Without Abstract
The online version of this article (doi:10.1007/s13238-014-0042-3) contains supplementary material, which is available to authorized users.
Article: PLOS Biology
How Do Filamentous Pathogens Deliver Effector Proteins into Plant Cells?
B. Petre and S. Kamoun
Plos Biology, DOI: 10.1371/journal.pbio.1001801
Abstract
Fungal and oomycete plant parasites are among the most devastating pathogens of food crops. These microbes secrete effector proteins inside plant cells to manipulate host processes and facilitate colonization. How these effectors reach the host cytoplasm remains an unclear and debated area of plant research. In this article, we examine recent conflicting findings that have generated discussion in the field. We also highlight promising approaches based on studies of both parasite and host during infection. Ultimately, this knowledge may inform future broad spectrum strategies for protecting crops from such pathogens.
Article: Mycorrhiza
Climatic variations explain annual fluctuations in French Périgord black truffle wholesale markets but do not explain the decrease in black truffle production over the last 48 years. F Le Tacon, B Marçais, M Courvoisier, C Murat, P Montpied, M Becker. Mycorrhiza.
Abstract
Production of the black truffle (Tuber melanosporum Vittad.) has experienced a decline in France
over the last century. Different sociological factors as well as climate change have been suggested as possible explanations for this decline. The aims of this study were to assess the effects of annual climatic variations on black truffle sales by analysing reliable data. Over the past 25 years, almost 90%of French truffle sales occurred in the southeastern region of France and, despite a decrease in southwestern France, for the last 25 years, sales were stable for France as a whole. An analysis of the two main southeastern wholesale markets (Richerenches and Carpentras) revealed that the main factor explaining the huge annual variations was the cumulative hydric balance from May to August of the year n. For the first time, frost days were also identified as an important factor in Richerenches. Using the model established for the past 25 years and the climatic data for the Richerenches and Carpentras basins, the truffle sales would have been stable from 1965 to nowadays. This simulation suggested that the production decline observed since 48 years could be attributed more to the change of rural world than to the climatic changes. The stability of production or the slight increase observed during the last 25 years could reflect the input of truffle orchards recently planted.
Article:Molecular Plant-Microbe Interactions
Populus trichocarpa and Populus deltoides Exhibit Different Metabolomic Responses to Colonization by the Symbiotic fungus Laccaria bicolor
TJ Tschaplinski, JM Plett, N Engle, A Deveau, K Cushman, MZ Martin, …
Molecular Plant-Microbe Interactions
Abstract
Within boreal and temperate forest ecosystems the majority of trees and shrubs form beneficial relationships with mutualistic ectomycorrhizal fungi (ECM) that support plant health through increased access to nutrients as well as aiding in stress and pest tolerance. The intimate interaction between fungal hyphae and plant roots result in a new symbiotic ‘organ’ called the ECM root tip. Little is understood concerning the metabolic re-programming that favors the formation of this hybrid tissue in compatible interactions and what prevents the formation of ECM root tips in incompatible interactions. We show here that the metabolic changes during favorable colonization between the ECM fungus Laccaria bicolor and its compatible host, Populus trichocarpa, are characterized by shifts in aromatic acid, organic acid, and fatty acid metabolism. We demonstrate that this extensive metabolic re-programming is repressed in incompatible interactions and that more defensive compounds are produced or retained. We also demonstrate that L. bicolor can metabolize a number of secreted defensive compounds and that the degradation of some of these compounds produce immune response metabolites (e.g., salicylic acid from salicin). Therefore, our results suggest that the metabolic responsiveness of plant roots to L. bicolor is a determinant factor in fungal:host interactions.
Article: Genome Announcements
Genome Sequence of the Mycorrhizal Helper Bacterium Pseudomonas fluorescens BBc6R8
A Deveau, H Gross, E Morin, T Karpinets, S Utturkar, S Mehnaz, F Martin, P …
Genome Announcements 2 (1), e01152-13
ABSTRACT
We report the draft genome sequence of the mycorrhizal helper bacteriumPseudomonas fluorescens strain BBc6R8. This is the first genome of a mycorrhizal helper bacterium. The draft genome contains 6,952,353 bp and is predicted to encode 6,317 open reading frames. Comparative genomic analyses will help to identify helper traits.
Article: New Phytologist
Ethylene and jasmonic acid act as negative modulators during mutualistic symbiosis between Laccaria bicolor and Populus roots. J. Plett, A. Khatchane, M. Ouassou, B. Sundberg, A. Kohler, F. Martin. New Phytologist
Summary
- The plant hormones ethylene, jasmonic acid and salicylic acid have interconnecting roles during the response of plant tissues to mutualistic and pathogenic symbionts.
- We used morphological studies of transgenic- or hormone-treated Populus roots as well as whole-genome oligoarrays to examine how these hormones affect root colonization by the mutualistic ectomycorrhizal fungus Laccaria bicolor S238N.
- We found that genes regulated by ethylene, jasmonic acid and salicylic acid were regulated in the late stages of the interaction between L. bicolor and poplar. Both ethylene and jasmonic acid treatments were found to impede fungal colonization of roots, and this effect was correlated to an increase in the expression of certain transcription factors (e.g. ETHYLENE RESPONSE FACTOR1) and a decrease in the expression of genes associated with microbial perception and cell wall modification. Further, we found that ethylene and jasmonic acid showed extensive transcriptional cross-talk, cross-talk that was opposed by salicylic acid signaling.
- We conclude that ethylene and jasmonic acid pathways are induced late in the colonization of root tissues in order to limit fungal growth within roots. This induction is probably an adaptive response by the plant such that its growth and vigor are not compromised by the fungus.
Article: Frontiers in Plant Science
Towards a refined classification of class I dithiol glutaredoxins from poplar: biochemical basis for the definition of two subclasses
J Couturier, JP Jacquot, N Rouhier
Frontiers in Plant Science 4, 518
Glutaredoxins (Grxs) are small oxidoreductases particularly specialized in the reduction of protein-glutathione adducts. Compared to other eukaryotic organisms, higher plants present an increased diversity of Grxs which are organized into four classes. This work presents a thorough comparative analysis of the biochemical and catalytic properties of dithiol class I Grxs from poplar, namely GrxC1, GrxC2, GrxC3 and GrxC4. By evaluating the in vitro oxidoreductase activity of wild type and cysteine mutated variants and by determining their dithiol-disulfide redox potentials, pKa values of the catalytic cysteine, redox state changes in response to oxidative treatments, two subgroups can be distinguished. In accordance with their probable quite recent duplication, GrxC1 and GrxC2 are less efficient catalysts for the reduction of dehydroascorbate and hydroxyethyldisulfide compared to GrxC3 and GrxC4, and they can form covalent dimers owing to the presence of an additional C-terminal cysteine (CysC). Interestingly, the second active site cysteine (CysB) influences the reactivity of the catalytic cysteine (CysA) in GrxC1 and GrxC2 as already observed with GrxC5 (restricted to A. thaliana), but not in GrxC3 and C4. However, all proteins can form an intramolecular disulfide between the two active site cysteines (CysA-CysB) which could represent either a protective mechanism considering that this second cysteine is dispensable for deglutathionylation reaction or a true catalytic intermediate occurring during the reduction of particular disulfide substrates or in specific conditions or compartments where glutathione levels are insufficient to support Grx regeneration. Overall, in addition to their different sub-cellular localization and expression pattern, the duplication and maintenance along evolution of several class I Grxs in higher plants can be explained by the existence of differential biochemical and catalytic properties.
Article: Environmental Microbiology
Diversity and structure of bacterial communities associated with Phanerochaete chrysosporium during wood decay. V Hervé, X Le Roux, S Uroz, E Gelhaye, P Frey‐Klett
Environmental Microbiology
Abstract
Wood recycling is key to forest biogeochemical cycles, largely driven by microorganisms such as white-rot fungi which naturally coexist with bacteria in the environment. We have tested whether and to what extent the diversity of the bacterial community associated with wood decay is determined by wood and/or by white-rot fungus Phanerochaete chrysosporium. We combined a microcosm approach with an enrichment procedure, using beech sawdust inoculated with or without P. chrysosporium. During eighteen weeks, we used 16S rRNA gene-based pyrosequencing to monitor the forest bacterial community inoculated into these microcosms. We found bacterial communities associated with wood to be substantially less diverse than the initial forest soil inoculum. The presence of most bacterial OTUs varied over time and between replicates, regardless of their treatment, suggestive of the stochastic processes. However, we observed two OTUs belonging to Xanthomonadaceae and Rhizobium, together representing 50% of the relative bacterial abundance, as consistently associated with the wood substrate, regardless of fungal presence. Moreover, after twelve weeks, the bacterial community composition based on relative abundance was significantly modified by the presence of the white-rot fungus. Effectively, members of the Burkholderiagenus were always associated with P. chrysoporium, representing potential taxonomic bioindicators of the white-rot mycosphere.
