Expérimentation de systèmes viticoles à faible usage d’intrants phytosanitaires en Val de Loire.

Ce numéro est constitué d’articles de synthèse des projets DEPHY EXPE publiés à l’occasion du colloque national DEPHY, qui s’est déroulé les 13 et 14 novembre 2018 à la Cité des Sciences et de l'Industrie (Paris). Nous vous invitons à découvrir le bilan et les enseignements des 21 projets conduits sur la période 2012-2017.The EcoViti Val de Loire project evaluated various viticulture systems during 6 years. One system wasbased on a combination of already assessed practices (at the time of design), a second one on theimpact of the pruning system on diseases susceptibility, and the last on the association of grapevineand roses. These systems led to significant TFI reductions, with sometimes some drawbacks in terms ofyield. They also allowed to show the importance of the transition period in system experimentations, andthe interest to lead these experimentations from the plantation for perennial crops. The time for thesystem to get back in balance is not to be underestimated, even a plant as plastic as grapevine takesseveral years ti adapt to a change in pruning or soil management.Le projet EcoViti Val de Loire a évalué trois systèmes de culture viticoles pendant 6 ans. Le premiersystème était basé sur la combinaison de pratiques déjà éprouvées au moment du lancement du projet,un second sur l’impact du mode de taille de la vigne sur la sensibilité aux maladies, et le dernier surl’association de vigne et rosiers. Ces divers systèmes ont permis des réductions significatives d’IFT,avec parfois des revers, en termes de rendement notamment. Ils ont également mis en évidence lanécessité de prendre en compte la phase de transition dans les essais systèmes, et l’intérêt de menerles essais systèmes en culture pérenne dès la plantation. En effet, le temps de rééquilibrage d’uneplante pérenne n’est pas à sous-estimer, et même une plante aussi plastique que la vigne met plusieursannées pour s’adapter à une modification de taille ou de mode d’entretien du sol

The influence of climatic factors on downy mildew in two vineyards from France and Romania

The objective of this study was to evaluate the influence of climate variability from the last two years, namely 2021-2022, on the development of the pathogen Plasmopara viticola in two vineyards renowned for the quality of their wines, Murfatlar (Romania) and Val de Loire (France). The study was carried out on four grapevine cultivars: 'Sauvignon blanc' and 'Cabernet sauvignon', authorized for the production of CDO Murfatlar wines; and Cot and Chenin, authorized for the production of CDO Touraine wines. The results regarding the appearance and development of the disease on leaves and bunches in different grapevine development stages, on the two variants of the experiments (treated and untreated) highlighted different levels of attack depending on the distribution of precipitation and the evolution of average air temperatures during the vegetation period. The excess rainfall regime in 2021 of 339.3 mm in Murfatlar and 351.8 mm in Val de Loire, and the air temperatures of 20-25°C generated optimal conditions for the spread of disease on the leaves in the untreated variant, reaching a maximum of 48.3% in Murfatlar and 9.5% in Val de Loire during veraison. The disease also spread to the bunches, reaching a maximum of 86.2% in Murfatlar, endangering almost completely the production of grapes. In the case of the variant where phytosanitary treatments were applied, the degree of attack was a maximum of 4%. In 2022, against the background of quantitatively reduced precipitation compared to 2021, with 64.15% in Murfatlar and 45.01% in Val de Loire, the first oil spots were identified in the untreated variant during BBCH 55 (the emergence of inflorescences), having an insignificant spread, reaching a maximum of 8.9% in the cluster compaction phenophase (BBCH 77)

Antifungal Activity of Resveratrol Derivatives against Candida Species

trans-Resveratrol (1a) is a phytoalexin produced by plants in response to infections by pathogens. Its potential activity against clinically relevant opportunistic fungal pathogens has previously been poorly investigated. Evaluated herein are the candidacidal activities of oligomers (2a, 3–5) of 1a purified from Vitis vinifera grape canes and several analogues (1b–1j) of 1a obtained through semisynthesis using methylation and acetylation. Moreover, trans-ε-viniferin (2a), a dimer of 1a, was also subjected to methylation (2b) and acetylation (2c) under nonselective conditions. Neither the natural oligomers of 1a (2a, 3–5) nor the derivatives of 2a were active against Candida albicans SC5314. However, the dimethoxy resveratrol derivatives 1d and 1e exhibited antifungal activity against C. albicans with minimum inhibitory concentration (MIC) values of 29–37 μg/mL and against 11 other Candida species. Compound 1e inhibited the yeast-to-hyphae morphogenetic transition of C. albicans at 14 μg/mL

Identification of a Classical Bipartite Nuclear Localization Signal in the Drosophila TEA/ATTS Protein Scalloped

Drosophila melanogaster wing development has been shown to rely on the activity of a complex of two proteins, Scalloped (Sd) and Vestigial (Vg). Within this complex, Sd is known to provide DNA binding though its TEA/ATTS domain, while Vg modulates this binding and provides transcriptional activation through N- and C-terminal activation domains. There is also evidence that Sd is required for the nuclear translocation of Vg. Indeed, a candidate sequence which shows consensus to the bipartite family of nuclear localization signals (NLSs) has been identified within Sd previously, though it is not known if it is functional, or if additional unpredicted signals that mediate nuclear transport exist within the protein. By expressing various enhanced green fluorescent protein (eGFP) tagged constructs within Drosophila S2 cells, we demonstrate that this NLS is indeed functional and necessary for the proper nuclear localization of Sd. Additionally, the region containing the NLS is critical for the wildtype function of ectopically expressed Sd, in the context of wing development. Using site-directed mutagenesis, we have identified a group of five amino acids within this NLS which is critical for its function, as well as another group of two which is of lesser importance. Together with data that suggests that this sequence mediates interactions with Importin-α3, we conclude that the identified NLS is likely a classical bipartite signal. Further dissection of Sd has also revealed that a large portion of the C-terminal domain of the protein is required its proper nuclear localization. Finally, a Leptomycin B (LB) sensitive signal which appears to facilitate nuclear export is identified, raising the possibility that Sd also contains a nuclear export signal (NES)

Evidence for a Transport-Trap Mode of Drosophila melanogaster gurken mRNA Localization

The Drosophila melanogaster gurken gene encodes a TGF alpha-like signaling molecule that is secreted from the oocyte during two distinct stages of oogenesis to define the coordinate axes of the follicle cell epithelium that surrounds the oocyte and its 15 anterior nurse cells. Because the gurken receptor is expressed throughout the epithelium, axial patterning requires region-specific secretion of Gurken protein, which in turn requires subcellular localization of gurken transcripts. The first stage of Gurken signaling induces anteroposterior pattern in the epithelium and requires the transport of gurken transcripts from nurse cells into the oocyte. The second stage of Gurken signaling induces dorsovental polarity in the epithelium and requires localization of gurken transcripts to the oocyte's anterodorsal corner. Previous studies, relying predominantly on real-time imaging of injected transcripts, indicated that anterodorsal localization involves transport of gurken transcripts to the oocyte's anterior cortex followed by transport to the anterodorsal corner, and anchoring. Such studies further indicated that a single RNA sequence element, the GLS, mediates both transport steps by facilitating association of gurken transcripts with a cytoplasmic dynein motor complex. Finally, it was proposed that the GLS somehow steers the motor complex toward that subset of microtubules that are nucleated around the oocyte nucleus, permitting directed transport to the anterodorsal corner. Here, we re-investigate the role of the GLS using a transgenic fly assay system that includes use of the endogenous gurken promoter and biological rescue as well as RNA localization assays. In contrast to previous reports, our studies indicate that the GLS is sufficient for anterior localization only. Our data support a model in which anterodorsal localization is brought about by repeated rounds of anterior transport, accompanied by specific trapping at the anterodorsal cortex. Our data further indicate that trapping at the anterodorsal corner requires at least one as-yet-unidentified gurken RLE

Transient exposure to low levels of insecticide affects metabolic networks of honeybee larvae

The survival of a species depends on its capacity to adjust to changing environmental conditions, and new stressors. Such new, anthropogenic stressors include the neonicotinoid class of crop-protecting agents, which have been implicated in the population declines of pollinating insects, including honeybees (Apis mellifera). The low-dose effects of these compounds on larval development and physiological responses have remained largely unknown. Over a period of 15 days, we provided syrup tainted with low levels (2 µg/L−1) of the neonicotinoid insecticide imidacloprid to beehives located in the field. We measured transcript levels by RNA sequencing and established lipid profiles using liquid chromatography coupled with mass spectrometry from worker-bee larvae of imidacloprid-exposed (IE) and unexposed, control (C) hives. Within a catalogue of 300 differentially expressed transcripts in larvae from IE hives, we detect significant enrichment of genes functioning in lipid-carbohydrate-mitochondrial metabolic networks. Myc-involved transcriptional response to exposure of this neonicotinoid is indicated by overrepresentation of E-box elements in the promoter regions of genes with altered expression. RNA levels for a cluster of genes encoding detoxifying P450 enzymes are elevated, with coordinated downregulation of genes in glycolytic and sugar-metabolising pathways. Expression of the environmentally responsive Hsp90 gene is also reduced, suggesting diminished buffering and stability of the developmental program. The multifaceted, physiological response described here may be of importance to our general understanding of pollinator health. Muscles, for instance, work at high glycolytic rates and flight performance could be impacted should low levels of this evolutionarily novel stressor likewise induce downregulation of energy metabolising genes in adult pollinators

Projet EcoViti Val de Loire-Centre : expérimentation de systèmes viticoles à faible usage d’intrants phytosanitaires en Val de Loire.

Le projet EcoViti Val de Loire a évalué trois systèmes de culture viticoles pendant 6 ans. Le premier système était basé sur la combinaison de pratiques déjà éprouvées au moment du lancement du projet, un second sur l’impact du mode de taille de la vigne sur la sensibilité aux maladies, et le dernier sur l’association de vigne et rosiers. Ces divers systèmes ont permis des réductions significatives d’IFT, avec parfois des revers, en termes de rendement notamment. Ils ont également mis en évidence la nécessité de prendre en compte la phase de transition dans les essais systèmes, et l’intérêt de mener les essais systèmes en culture pérenne dès la plantation. En effet, le temps de rééquilibrage d’une plante pérenne n’est pas à sous-estimer, et même une plante aussi plastique que la vigne met plusieurs années pour s’adapter à une modification de taille ou de mode d’entretien du sol.The EcoViti Val de Loire project evaluated various viticulture systems during 6 years. One system was based on a combination of already assessed practices (at the time of design), a second one on the impact of the pruning system on diseases susceptibility, and the last on the association of grapevine and roses. These systems led to significant TFI reductions, with sometimes some drawbacks in terms of yield. They also allowed to show the importance of the transition period in system experimentations, and the interest to lead these experimentations from the plantation for perennial crops. The time for the system to get back in balance is not to be underestimated, even a plant as plastic as grapevine takes several years ti adapt to a change in pruning or soil management