The SCOOP 12 peptide regulates defense response and root development in Arabidopsis thaliana

Small secreted peptides are important players in plant development and stress response. Using a targeted in silico approach, we identified a family of 14 Arabidopsis genes encoding precursors of serine-rich endogenous peptides (PROSCOOP). Transcriptomic analyses revealed that one member of this family, PROSCOOP12, is involved in processes linked to biotic and oxidative stress as well as root growth. Plants defective in this gene were less susceptible to Erwinia amylovora infection and showed an enhanced root growth phenotype. In PROSCOOP12 we identified a conserved motif potentially coding for a small secreted peptide. Exogenous application of synthetic SCOOP12 peptide induces various defense responses in Arabidopsis. Our findings show that SCOOP12 has numerous properties of phytocytokines, activates the phospholipid signaling pathway, regulates reactive oxygen species response, and is perceived in a BAK1 co-receptor-dependent manner

Modeling denitrification in aquatic sediments

Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Biogeochemistry 93 (2009): 159-178, doi:10.1007/s10533-008-9270-z.Sediment denitrification is a major pathway of fixed nitrogen loss from aquatic systems. Due to technical difficulties in measuring this process and its spatial and temporal variability, estimates of local, regional and global denitrification have to rely on a combination of measurements and models. Here we review approaches to describing denitrification in aquatic sediments, ranging from mechanistic diagenetic models to empirical parameterizations of nitrogen fluxes across the sediment-water interface. We also present a compilation of denitrification measurements and ancillary data for different aquatic systems, ranging from freshwater to marine. Based on this data compilation we reevaluate published parameterizations of denitrification. We recommend that future models of denitrification use (1) a combination of mechanistic diagenetic models and measurements where bottom waters are temporally hypoxic or anoxic, and (2) the much simpler correlations between denitrification and sediment oxygen consumption for oxic bottom waters. For our data set, inclusion of bottom water oxygen and nitrate concentrations in a multivariate regression did not improve the statistical fit.Financial support for AEG to work on the manuscript came from NSF NSF-DEB-0423565. KF, DB and DDT acknowledge support from NOAA CHRP grant NA07NOS4780191

Sensitivity analysis of hydrological modelling to climate forcing in a semi-arid mountainous catchment.

International audienceThis study analyses the sensitivity of a hydrological model to different ways of interpolatingclimate forcing on the Elqui basin (5660 km2) in the Chilean Andes. A 36-year period (1976–2011) waschosen in order to account for the hydro-climatic variability. Precipitation and using the inverse distanceweighted methods were interpolated on a 5 × 5 km grid based on 12 and eight stations, respectively. Elevation effects on precipitation and temperature distribution were considered using a digital elevationmodel. Two precipitation datasets (with and without a mean altitudinal gradient) and three temperaturedatasets (using constant or monthly lapse rates based on altitudinal bands) were computed. All datasetcombinations were assessed through the calibration of the GR4j model including a snow reservoir.Calibration was performed by the succession of Rosenbrock and simplex algorithms using a multi-objectivefunction. Results show that the dataset based on a constant lapse rate of 6.5°C/km for temperature and noelevation effects for precipitation is sufficient to accurately simulate discharge and the snowmelt regime ofthe catchment over the last 30 years

Accounting for hydro-climatic and water use variability in the assessment of past and future water balance at the basin scale

International audienceThis study assesses water stress by 2050 in river basins facing increasing human and climatic pressures, by comparing the impacts of various combinations of possible future socio-economic and climate trends. A modelling framework integrating human and hydro-climatic dynamics and accounting for interactions between resource and demand at a 10-day time step was developed and applied in two basins of different sizes and with contrasted water uses: the Herault (2500 km2, France) and the Ebro (85 000 km2, Spain) basins. Natural streamflow was evaluated using a conceptual hydrological model (GR4j). A demand-driven reservoir management model was designed to account for streamflow regulations from the main dams. Urban water demand was estimated from time series of population and monthly unit water consumption data. Agricultural water demand was computed from time series of irrigated area, crop and soil data, and climate forcing. Indicators comparing water supply to demand at strategic resource and demand nodes were computed. This framework was successfully calibrated and validated under non-stationary human and hydro-climatic conditions over the last 40 years before being applied under four combinations of climatic and water use scenarios to differentiate the impacts of climate- and human-induced changes on streamflow and water balance. Climate simulations from the CMIP5 exercise were used to generate 18 climate scenarios at the 2050 horizon. A baseline water use scenario for 2050 was designed based on demographic and local socio-economic trends. Results showed that projected water uses are not sustainable under climate change scenarios

Evolution des déséquilibres quantitatifs, adaptation aux changements climatiques et anthropiques au sein de deux hydrosystèmes méditerranéens : l'Hérault et l'Ebre

International audienceLes évolutions climatiques et anthropiques récentes et à venir dans la région méditerranéenne posent la question de l’équilibre entre usages et ressources en eau dans les bassins versants. Cet équilibre dépend de l’évolution conjuguée de l’état quantitatif des ressources en eau et des usages anthropiques. Le travail présenté vise à comprendre les interactions entre usages et ressources en eau au sein d’hydrosystèmes anthropisés, en tenant compte des dynamiques spatio-temporelles de variables physiques et socio-économiques, et à analyser l’influence d’un large spectre de futurs possibles sur les déséquilibres quantitatifs et les stratégies d’adaptation envisagées

Assessing the capacity to meet irrigation water needs for viticulture under climate variability in the Chilean Andes

International audienc

Diagnostic du risque de pollution nitrique : du modèle à l'indicateur

Diffusion du document : INRA Unité Mixte de Recherche GAEL Laboratoire d'Economie appliquée de Grenoble Université Pierre Mendès France BP 47 38040 Grenoble Cedex 9 (FRA) (GRE2005) 2005-10La pollution nitrique menace de nombreuses ressources en eau en Europe. Elle est particulièrement inquiétante dans le Nord-Ouest de la France où de nombreux captages ont été abandonnés pour cause de dépassement des normes de potabilité. L'agriculture est une cause majeure de pollution nitrique. La lutte contre cette pollution diffuse nécessite de représenter les processus d'émission et de transfert pour accroître l'efficacité des actions de protection. De nombreux outils ont été développés pour évaluer cette pollution en allant d'indicateurs relativement simples à des modèles complexes. Les règles de choix entre les multiples outils sont rarement explicitées. Les auteurs utilisent deux types d'outils sur un même bassin versant afin de comparer leurs conditions de mise en oeuvre (données mobilisées et méthodes de traitement) et leurs résultats. Les deux outils sont : un indicateur d'émissions polluantes et le modèle agro-hydrologique Swat. La comparaison permet d'éclairer les choix par certaines règles liées aux besoins et aux contextes d'application. (A paraître dans : International Journal of Agricultural Resources Governance and Ecology)

Comparaison de méthodes de suivi de l'occupation du sol pendant 50 ans à partir de photos aériennes et satellites dans un bassin sahélien

International audienceLand use/cover change (LUCC) is a major indicator of the impacts of climate change and human activity, particularly in the Sahel, where the land cover has changed greatly over the last 50 years. Aerial and satellite sensors have been taking images of the earth's surface for several decades, providing repeated, systematic coverage of large areas that offers a unique documentary source for characterizing change in environmental resources. These data have been widely used to monitor LUCC, but many questions remain concerning what type of pre-processing should be carried out on image resolutions and which methods are most appropriate for successfully mapping patterns and dynamics in both croplands and natural vegetation. This paper aims at considering those methodological questions. It uses multi-source imagery from 1952 to 2003 (aerial photographs, Corona, Landsat MSS, Landsat TM and SPOT 5) and pursues two objectives: i) to implement and compare a number of processing chains on the basis of multi-sensor data, in order ii) to accurately track and quantify LUCC in a 100 km² Sahelian area over 50 years. The heterogeneity of the images' spatial and spectral resolutions led us to compare post-classification comparison methods aimed at producing coherent diachronic maps based on a common land-cover nomenclature. Three main approaches were tested: pixel-based classification, vector-grid-based on-screen interpretation and object-oriented classification. Within the automated approaches, we also examined the influence of spectral synthesis and spatial homogenization of the data through the use of composite bands (principal components analysis, indices) and by resampling images at a common resolution. Classification accuracy was estimated by computing confusion matrices, by analyzing overall change in the relative areas of land use/cover types and by studying the geographical coherence of the changes. These analyses indicated that on-screen interpretation was the most suitable approach for providing coherent, valid results from the multi-source images available over the study period. However, satisfactory classifications were obtained with the pixel-based and object-oriented approaches. The results also showed significant sensitivity, depending on the method considered, to the combinations of bands used and to resampling. Lastly, the 50-year trends in LUCC indicated a large increase in croplands and erosional surfaces with sparse vegetation and a drastic reduction in woody covers