DNA Repair and the Stability of the Plant Mitochondrial Genome

International audienc

Soil organic carbon stocks in native forest of Argentina: a useful surrogate for mitigation and conservation planning under climate variability

Background The nationally determined contribution (NDC) presented by Argentina within the framework of the Paris Agreement is aligned with the decisions made in the context of the United Nations Framework Convention on Climate Change (UNFCCC) on the reduction of emissions derived from deforestation and forest degradation, as well as forest carbon conservation (REDD+). In addition, climate change constitutes one of the greatest threats to forest biodiversity and ecosystem services. However, the soil organic carbon (SOC) stocks of native forests have not been incorporated into the Forest Reference Emission Levels calculations and for conservation planning under climate variability due to a lack of information. The objectives of this study were: (i) to model SOC stocks to 30 cm of native forests at a national scale using climatic, topographic and vegetation as predictor variables, and (ii) to relate SOC stocks with spatial–temporal remotely sensed indices to determine biodiversity conservation concerns due to threats from high inter‑annual climate variability. Methods We used 1040 forest soil samples (0–30 cm) to generate spatially explicit estimates of SOC native forests in Argentina at a spatial resolution of approximately 200 m. We selected 52 potential predictive environmental covariates, which represent key factors for the spatial distribution of SOC. All covariate maps were uploaded to the Google Earth Engine cloud‑based computing platform for subsequent modelling. To determine the biodiversity threats from high inter‑annual climate variability, we employed the spatial–temporal satellite‑derived indices based on Enhanced Vegetation Index (EVI) and land surface temperature (LST) images from Landsat imagery. Results SOC model (0–30 cm depth) prediction accounted for 69% of the variation of this soil property across the whole native forest coverage in Argentina. Total mean SOC stock reached 2.81 Pg C (2.71–2.84 Pg C with a probability of 90%) for a total area of 460,790 km2, where Chaco forests represented 58.4% of total SOC stored, followed by Andean Patagonian forests (16.7%) and Espinal forests (10.0%). SOC stock model was fitted as a function of regional climate, which greatly influenced forest ecosystems, including precipitation (annual mean precipitation and precipitation of warmest quarter) and temperature (day land surface temperature, seasonality, maximum temperature of warmest month, month of maximum temperature, night land surface temperature, and monthly minimum temperature). Biodiversity was influenced by the SOC levels and the forest regions. Conclusions In the framework of the Kyoto Protocol and REDD+, information derived in the present work from the estimate of SOC in native forests can be incorporated into the annual National Inventory Report of Argentina to assist forest management proposals. It also gives insight into how native forests can be more resilient to reduce the impact of biodiversity loss.EEA Santa CruzFil: Peri, Pablo Luis. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Santa Cruz; Argentina.Fil: Peri, Pablo Luis. Universidad Nacional de la Patagonia Austral; Argentina.Fil: Peri, Pablo Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Gaitan, Juan José. Universidad Nacional de Luján. Buenos Aires; Argentina.Fil: Gaitan, Juan José. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Mastrangelo, Matias Enrique. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Grupo de Estudio de Agroecosistemas y Paisajes Rurales; Argentina.Fil: Mastrangelo, Matias Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Nosetto, Marcelo Daniel. Universidad Nacional de San Luis. Instituto de Matemática Aplicada San Luis. Grupo de Estudios Ambientales; Argentina.Fil: Nosetto, Marcelo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Villagra, Pablo Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA); Argentina.Fil: Villagra, Pablo Eugenio. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina.Fil: Balducci, Ezequiel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Yuto; Argentina.Fil: Pinazo, Martín Alcides. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Montecarlo; Argentina.Fil: Eclesia, Roxana Paola. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Paraná; Argentina.Fil: Von Wallis, Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Montecarlo; Argentina.Fil: Villarino, Sebastián. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Grupo de Estudio de Agroecosistemas y Paisajes Rurales; Argentina.Fil: Villarino, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Alaggia, Francisco Guillermo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Manfredi. Campo Anexo Villa Dolores; Argentina.Fil: Alaggia, Francisco Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Gonzalez-Polo, Marina. Universidad Nacional del Comahue; Argentina.Fil: Gonzalez-Polo, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. INIBIOMA; Argentina.Fil: Manrique, Silvana M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Energía No Convencional. CCT Salta‑Jujuy; Argentina.Fil: Meglioli, Pablo A. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA); Argentina.Fil: Meglioli, Pablo A. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina.Fil: Rodríguez‑Souilla, Julián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Mónaco, Martín H. Ministerio de Ambiente y Desarrollo Sostenible. Dirección Nacional de Bosques; Argentina.Fil: Chaves, Jimena Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina.Fil: Medina, Ariel. Ministerio de Ambiente y Desarrollo Sostenible. Dirección Nacional de Bosques; Argentina.Fil: Gasparri, Ignacio. Universidad Nacional de Tucumán. Instituto de Ecología Regional; Argentina.Fil: Gasparri, Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Alvarez Arnesi, Eugenio. Universidad Nacional de Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina.Fil: Alvarez Arnesi, Eugenio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentina.Fil: Barral, María Paula. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias. Grupo de Estudio de Agroecosistemas y Paisajes Rurales; Argentina.Fil: Barral, María Paula. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Von Müller, Axel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Esquel Argentina.Fil: Pahr, Norberto Manuel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Montecarlo; Argentina.Fil: Uribe Echevarría, Josefina. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Quimilí; Argentina.Fil: Fernandez, Pedro Sebastian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Famaillá; Argentina.Fil: Fernandez, Pedro Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecología Regional; Argentina.Fil: Morsucci, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA); Argentina.Fil: Morsucci, Marina. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina.Fil: Lopez, Dardo Ruben. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Manfredi. Campo Anexo Villa Dolores; Argentina.Fil: Lopez, Dardo Ruben. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Cellini, Juan Manuel. Universidad Nacional de la Plata (UNLP). Facultad de Ciencias Naturales y Museo. Laboratorio de Investigaciones en Maderas; Argentina.Fil: Alvarez, Leandro M. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA); Argentina.Fil: Alvarez, Leandro M. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina.Fil: Barberis, Ignacio Martín. Universidad Nacional de Rosario. Instituto de Investigaciones en Ciencias Agrarias de Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentina.Fil: Barberis, Ignacio Martín. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentina.Fil: Colomb, Hernán Pablo. Ministerio de Ambiente y Desarrollo Sostenible. Dirección Nacional de Bosques; Argentina.Fil: Colomb, Hernán. Administración de Parques Nacionales (APN). Parque Nacional Los Alerces; Argentina.Fil: La Manna, Ludmila. Universidad Nacional de la Patagonia San Juan Bosco. Centro de Estudios Ambientales Integrados (CEAI); Argentina.Fil: La Manna, Ludmila. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Barbaro, Sebastian Ernesto. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cerro Azul; Argentina.Fil: Blundo, Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ecología Regional; Argentina.Fil: Blundo, Cecilia. Universidad Nacional de Tucumán. Tucumán; Argentina.Fil: Sirimarco, Marina Ximena. Universidad Nacional de Mar del Plata. Grupo de Estudio de Agroecosistemas y Paisajes Rurales (GEAP); Argentina.Fil: Sirimarco, Marina Ximena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.Fil: Cavallero, Laura. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Manfredi. Campo Anexo Villa Dolores; Argentina.Fil: Zalazar, Gualberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA); Argentina.Fil: Zalazar, Gualberto. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina.Fil: Martínez Pastur, Guillermo José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas (CADIC); Argentina

Atypical thioredoxins in poplar: the glutathione-dependent thioredoxin-like 2.1 supports the activity of target enzymes possessing a single redox active cysteine

Plant thioredoxins (Trxs) constitute a complex family of thiol oxidoreductases generally sharing a WCGPC active site sequence. Some recently identified plant Trxs (Clot, Trx-like1 and -2, Trx-lilium1, -2, and -3) display atypical active site sequences with altered residues between the two conserved cysteines. The transcript expression patterns, subcellular localizations, and biochemical properties of some representative poplar (Populus spp.) isoforms were investigated. Measurements of transcript levels for the 10 members in poplar organs indicate that most genes are constitutively expressed. Using transient expression of green fluorescent protein fusions, Clot and Trx-like1 were found to be mainly cytosolic, whereas Trx-like2.1 was located in plastids. All soluble recombinant proteins, except Clot, exhibited insulin reductase activity, although with variable efficiencies. Whereas Trx-like2.1 and Trx-lilium2.2 were efficiently regenerated both by NADPH-Trx reductase and glutathione, none of the proteins were reduced by the ferredoxin-Trx reductase. Only Trx-like2.1 supports the activity of plastidial thiol peroxidases and methionine sulfoxide reductases employing a single cysteine residue for catalysis and using a glutathione recycling system. The second active site cysteine of Trx-like2.1 is dispensable for this reaction, indicating that the protein possesses a glutaredoxin-like activity. Interestingly, the Trx-like2.1 active site replacement, from WCRKC to WCGPC, suppresses its capacity to use glutathione as a reductant but is sufficient to allow the regeneration of target proteins employing two cysteines for catalysis, indicating that the nature of the residues composing the active site sequence is crucial for substrate selectivity/recognition. This study provides another example of the cross talk existing between the glutathione/glutaredoxin and Trx-dependent pathways

Structural and enzymatic insights into Lambda glutathione transferases from Populus trichocarpa, monomeric enzymes constituting an early divergent class specific to terrestrial plants

International audienceGSTs represent a superfamily of multifunctional proteins which play crucial roles in detoxification processes and secondary metabolism. Instead of promoting the conjugation of glutathione to acceptor molecules as do most GSTs, members of the Lambda class (GSTLs) catalyse deglutathionylation reactions via a catalytic cysteine residue. Three GSTL genes (Pt-GSTL1, Pt-GSTL2 and Pt-GSTL3) are present in Populus trichocarpa, but two transcripts, differing in their 5' extremities, were identified for Pt-GSTL3. Transcripts for these genes were primarily found in flowers, fruits, petioles and buds, but not in leaves and roots, suggesting roles associated with secondary metabolism in these organs. The expression of GFP-fusion proteins in tobacco showed that Pt-GSTL1 is localized in plastids, whereas Pt-GSTL2 and Pt-GSTL3A and Pt-GSTL3B are found in both the cytoplasm and the nucleus. The resolution of Pt-GSTL1 and Pt-GSTL3 structures by X-ray crystallography indicated that, although these proteins adopt a canonical GST fold quite similar to that found in dimeric Omega GSTs, their non-plant counterparts, they are strictly monomeric. This might explain some differences in the enzymatic properties of both enzyme types. Finally, from competition experiments between aromatic substrates and a fluorescent probe, we determined that the recognition of glutathionylated substrates is favoured over non-glutathionylated forms

Plastidic P2 glucose-6P dehydrogenase from poplar is modulated by thioredoxin m-type: Distinct roles of cysteine residues in redox regulation and NADPH inhibition

A cDNA coding for a plastidic P2-type G6PDH isoform from poplar (Populus tremula x tremuloides) has been used to express and purify to homogeneity the mature recombinant protein with a N-terminus His-tag. The study of the kinetic properties of the recombinant enzyme showed an in vitro redox sensing modulation exerted by reduced DTT. The interaction with thioredoxins (TRX5) was then investigated.Five cysteine to serine variants (C145S - C175S - C183S - C195S - C242S) and a variant with a double substitution for Cys(175) and Cys(183) (C175S/C183S) have been generated, purified and biochemically characterized in order to investigate the specific role(s) of cysteines in terms of redox regulation and NADPH - dependent inhibition.Three cysteine residues (C-145, C-194, C-242) are suggested to have a role in controlling the NADI)* access to the active site, and in stabilizing the NADPH regulatory binding site.Our results also indicate that the regulatory disulfide involves residues Cys(175) and Cys(183) in a position similar to those of chloroplastic P1-G6PDHs, but the modulation is exerted primarily by TRX m-type, in contrast to P1-G6PDH, which is regulated by TRX f.This unexpected specificity indicates differences in the mechanism of regulation, and redox sensing of plastidic P2-G6PDH compared to chloroplastic Pl - G6PDH in higher plants. (C) 2016 Elsevier Ireland Ltd. All rights reserved

Chloroplast monothiol glutaredoxins as scaffold proteins for the assembly and delivery of [2Fe–2S] clusters

Glutaredoxins (Grxs) are small oxidoreductases that reduce disulphide bonds or protein-glutathione mixed disulphides. More than 30 distinct grx genes are expressed in higher plants, but little is currently known concerning their functional diversity. This study presents biochemical and spectroscopic evidence for incorporation of a [2Fe–2S] cluster in two heterologously expressed chloroplastic Grxs, GrxS14 and GrxS16, and in vitro cysteine desulphurase-mediated assembly of an identical [2Fe–2S] cluster in apo-GrxS14. These Grxs possess the same monothiol CGFS active site as yeast Grx5 and both were able to complement a yeast grx5 mutant defective in Fe–S cluster assembly. In vitro kinetic studies monitored by CD spectroscopy indicate that [2Fe–2S] clusters on GrxS14 are rapidly and quantitatively transferred to apo chloroplast ferredoxin. These data demonstrate that chloroplast CGFS Grxs have the potential to function as scaffold proteins for the assembly of [2Fe–2S] clusters that can be transferred intact to physiologically relevant acceptor proteins. Alternatively, they may function in the storage and/or delivery of preformed Fe–S clusters or in the regulation of the chloroplastic Fe–S cluster assembly machinery

Functional, structural, and spectroscopic characterization of a glutathione-ligated [2Fe–2S] cluster in poplar glutaredoxin C1

When expressed in Escherichia coli, cytosolic poplar glutaredoxin C1 (CGYC active site) exists as a dimeric iron–sulfur-containing holoprotein or as a monomeric apoprotein in solution. Analytical and spectroscopic studies of wild-type protein and site-directed variants and structural characterization of the holoprotein by using x-ray crystallography indicate that the holoprotein contains a subunit-bridging [2Fe–2S] cluster that is ligated by the catalytic cysteines of two glutaredoxins and the cysteines of two glutathiones. Mutagenesis data on a variety of poplar glutaredoxins suggest that the incorporation of an iron–sulfur cluster could be a general feature of plant glutaredoxins possessing a glycine adjacent to the catalytic cysteine. In light of these results, the possible involvement of plant glutaredoxins in oxidative stress sensing or iron–sulfur biosynthesis is discussed with respect to their intracellular localization