Publications by authors named "Benoit Lacombe"

Photosynthesis determines plant growth, influencing plant nitrogen demand, hence it is also crucial to the regulation of nitrate uptake. It remains unclear how fast plants adjust root nitrate uptake in response to change in photosynthesis. This research aimed to investigate the instantaneous response of root nitrate uptake to shoot photosynthesis.

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Plant nitrogen nutrition is an essential and energy-costly component of terrestrial food chains. Understanding nitrate sensing in plants can lead to improved crop yields and nutrient use efficiency, directly impacting food security and agricultural sustainability. Herein, we review and present a comprehensive framework for understanding nitrate sensing in plants, integrating molecular, genetic, and physiological aspects.

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Plant root development depends on signaling pathways responding to external and internal signals. In this study we demonstrate the involvement of the Lotus japonicus LjNPF4.6 gene in the ABA and nitrate root responding pathways.

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Soil calcium carbonate (CaCO) impacts plant mineral nutrition far beyond Fe metabolism, imposing constraints for crop growth and quality in calcareous agrosystems. Our knowledge on plant strategies to tolerate CaCO effects mainly refers to Fe acquisition. This review provides an update on plant cellular and molecular mechanisms recently described to counteract the negative effects of CaCO in soils, as well as recent efforts to identify genetic bases involved in CaCO tolerance from natural populations, that could be exploited to breed CaCO-tolerant crops.

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Diatoms are a highly successful group of phytoplankton, well adapted also to oligotrophic environments and capable of handling nutrient fluctuations in the ocean, particularly nitrate. The presence of a large vacuole is an important trait contributing to their adaptive features. It confers diatoms the ability to accumulate and store nutrients, such as nitrate, when they are abundant outside and then to reallocate them into the cytosol to meet deficiencies, in a process called luxury uptake.

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Data from functional trait databases have been increasingly used to address questions related to plant diversity and trait-environment relationships. However, such databases provide intraspecific data that combine individual records obtained from distinct populations at different sites and, hence, environmental conditions. This prevents distinguishing sources of variation (e.

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Background And Aims: HDV, a satellite of HBV, is responsible for the most severe form of human viral hepatitis, for which curative therapy is still awaited. Both HBV and HDV use the hepatic transporter of bile acids (ie, Na+-taurocholate cotransporting polypeptide) to enter hepatocytes. We have previously shown that ligands of the farnesoid-X-receptor alpha (FXR), a master regulator of bile acids metabolism, inhibit HBV replication.

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Nutrient sensing and signaling are essential for adjusting growth and development to available resources. Deprivation of the essential mineral phosphorus (P) inhibits root growth. The molecular processes that sense P limitation to trigger early root growth inhibition are not known yet.

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Mineral nutrition is one of the key environmental factors determining plant development and growth. Nitrate is the major form of macronutrient nitrogen that plants take up from the soil. Fluctuating availability or deficiency of this element severely limits plant growth and negatively affects crop production in the agricultural system.

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The trait-based approach in plant ecology aims at understanding and classifying the diversity of ecological strategies by comparing plant morphology and physiology across organisms. The major drawback of the approach is that the time and financial cost of measuring the traits on many individuals and environments can be prohibitive. We show that combining near-infrared spectroscopy (NIRS) with deep learning resolves this limitation by quickly, non-destructively, and accurately measuring a suite of traits, including plant morphology, chemistry, and metabolism.

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Photosynthetic organisms convert light energy into chemical energy stored in carbohydrates. To perform this process, an adequate supply of essential mineral elements, such as iron, is required in the chloroplast. Because iron plays a crucial role during electron transport and chlorophyll formation, iron deficiency alters photosynthesis and promotes chlorosis, or the yellowing of leaves.

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Nitrate and potassium nutrition is tightly coordinated in vascular plants. Physiological and molecular genetics studies have demonstrated that several NPF/NRT1 nitrate transporters have a significant impact on both uptake and the root-shoot partition of these nutrients. However, how these traits are biochemically connected remain controversial since some NPF proteins, e.

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Plants need to cope with strong variations of nitrogen availability in the soil. Although many molecular players are being discovered concerning how plants perceive NO3- provision, it is less clear how plants recognize a lack of nitrogen. Following nitrogen removal, plants activate their nitrogen starvation response (NSR), which is characterized by the activation of very high-affinity nitrate transport systems (NRT2.

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Sugars and nitrate play a major role in providing carbon and nitrogen in plants. Understanding how plants sense these nutrients is crucial, most notably for crop improvement. The mechanisms underlying sugar and nitrate sensing are complex and involve moonlighting proteins such as the nitrate transporter NRT1.

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HIV transcription requires assembly of cellular transcription factors at the HIV-1promoter. The TFIIH general transcription factor facilitates transcription initiation by opening the DNA strands around the transcription start site and phosphorylating the C-terminal domain for RNA polymerase II (RNAPII) for activation. Spironolactone (SP), an FDA approved aldosterone antagonist, triggers the proteasomal degradation of the XPB subunit of TFIIH, and concurrently suppresses acute HIV infection Here we investigated SP as a possible block-and-lock agent for a functional cure aimed at the transcriptional silencing of the viral reservoir.

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Few proteins have been characterized as abscisic acid transporters. Several of them are NRT1/PRT Family (NPF) transporters which have been characterized in yeast using reporter systems. Because several members of the NPF4 subfamily members were identified in yeast as ABA transporters, here, we screened for ABA transport activity the seven members of the NPF4 subfamily in Xenopus oocytes using cRNA injection and H-ABA accumulation.

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Human T-cell lymphotropic virus type 1 (HTLV-1) Tax oncoprotein is required for viral gene expression. Tax transactivates the viral promoter by recruiting specific transcription factors but also by interfering with general transcription factors involved in the preinitiation step, such as TFIIA and TFIID. However, data are lacking regarding Tax interplay with TFIIH, which intervenes during the last step of preinitiation.

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Background: After uptake from soil into the root tissue, distribution and allocation of nitrate throughout the whole plant body, is a critical step of nitrogen use efficiency (NUE) and for modulation of plant growth in response to various environmental conditions. In legume plants nitrate distribution is also important for the regulation of the nodulation process that allows to fix atmospheric N (N) through the symbiotic interaction with rhizobia (symbiotic nitrogen fixation, SNF).

Results: Here we report the functional characterization of the Lotus japonicus gene LjNPF2.

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In nature, plants have to handle daily fluctuations in light and temperature. In addition, plants face biotic and abiotic stresses that often come in various combinations. For instance, the availability of various nutrients in soil is heterogeneous, resulting in combined nutrient stress.

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Nitrogen (N) and phosphorus (P) are key macronutrients sustaining plant growth and crop yield and ensuring food security worldwide. Understanding how plants perceive and interpret the combinatorial nature of these signals thus has important agricultural implications within the context of (1) increased food demand, (2) limited P supply, and (3) environmental pollution due to N fertilizer usage. Here, we report the discovery of an active control of P starvation response (PSR) by a combination of local and long-distance N signaling pathways in plants.

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Hepatitis B virus (HBV) infection and bile acid (BA) metabolism are interdependent: infection modifies the expression of the BA nuclear receptor farnesoid X receptor (FXR)-α, and modulation of FXRα activity by ligands alters HBV replication. Mechanisms of HBV control by FXRα remain to be unveiled. FXRα silencing in HBV-infected HepaRG cells decreased the viral covalently closed circular (ccc)DNA pool size and transcriptional activity.

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Plants face temporal and spatial variation in nitrogen (N) availability. This includes heterogeneity in soil nitrate (NO) content. To overcome these constraints, plants modify their gene expression and physiological processes to optimize N acquisition.

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Mineral nutrient homeostasis is essential for plant growth and development. Recent research has demonstrated that the occurrence of interactions among the mechanisms regulating the homeostasis of different nutrients in plants is a general rule rather than an exception. Therefore, it is important to understand how plants regulate the homeostasis of these elements and how multiple mineral nutrient signals are wired to influence plant growth.

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Engineering osmotolerant plants is a challenge for modern agriculture. An interaction between osmotic stress response and phosphate homeostasis has been reported in plants, but the identity of molecules involved in this interaction remains unknown. In this study we assessed the role of phytic acid (PA) in response to osmotic stress and/or phosphate deficiency in Arabidopsis thaliana.

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