Publications by authors named "Pierre Czernic"

Introduction: Arbuscular mycorrhizal fungi (AMF) belong to the Glomeromycota clade and can form root symbioses with 80% of Angiosperms, including crops species such as wheat, maize and rice. By increasing nutrient availability, uptake and soil anchoring of plants, AMF can improve plant's growth and tolerance to abiotic stresses. AMF can also reduce symptoms and pathogen load on infected plants, both locally and systemically, through a phenomenon called mycorrhiza induced resistance (MIR).

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The plant microbiome has recently emerged as a reservoir for the development of sustainable alternatives to chemical fertilizers and pesticides. However, the response of plants to beneficial microbes emerges as a critical issue to understand the molecular basis of plant-microbiota interactions. In this study, we combined root colonization, phenotypic and transcriptomic analyses to unravel the commonalities and specificities of the response of rice to closely related Burkholderia s.

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Meloidogyne graminicola, also known as the rice root-knot nematode, is one of the most damaging plant-parasitic nematode, especially on rice. This obligate soilborne parasite induces the formation of galls that disturb the root morphology and physiology. Its impact on the root microbiome is still not well described.

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In the context of plant-pathogen and plant-mutualist interactions, the underlying molecular bases associated with host colonization have been extensively studied. However, it is not the case for non-mutualistic beneficial interactions or associative symbiosis with plants. Particularly, little is known about the transcriptional regulations associated with the immune tolerance of plants towards beneficial microbes.

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In root-nodule symbiosis, rhizobial invasion and nodule organogenesis is host controlled. In most legumes, rhizobia enter through infection threads and nodule primordium in the cortex is induced from a distance. But in dalbergoid legumes like Arachis hypogaea, rhizobia directly invade cortical cells through epidermal cracks to generate the primordia.

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Nod factors (NF) were assumed to be indispensable for the establishment of a rhizobium-legume symbiosis until the discovery that certain Bradyrhizobium strains interacting with certain Aeschynomene species lack the canonical nodABC genes required for their synthesis. So far, the molecular dialogue between Aeschynomene and its symbionts remains an open question. Here we report a time course transcriptional analysis of Aeschynomene evenia in response to inoculation with Bradyrhizobium ORS278.

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Aeschynomene evenia has emerged as a new model legume for the deciphering of the molecular mechanisms of an alternative symbiotic process that is independent of the Nod factors. Whereas most of the research on nitrogen-fixing symbiosis, legume genetics and genomics has so far focused on Galegoid and Phaseolid legumes, A. evenia falls in the more basal and understudied Dalbergioid clade along with peanut (Arachis hypogaea).

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Nitrogen fixation in the legume-rhizobium symbiosis is a crucial area of research for more sustainable agriculture. Our knowledge of the plant cascade in response to the perception of bacterial Nod factors has increased in recent years. However, the discovery that Nod factors are not involved in the Aeschynomene-Bradyrhizobium spp.

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Nutritional symbiotic interactions require the housing of large numbers of microbial symbionts, which produce essential compounds for the growth of the host. In the legume-rhizobium nitrogen-fixing symbiosis, thousands of rhizobium microsymbionts, called bacteroids, are confined intracellularly within highly specialized symbiotic host cells. In Inverted Repeat-Lacking Clade (IRLC) legumes such as Medicago spp.

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Nodules of legume plants are highly integrated symbiotic systems shaped by millions of years of evolution. They harbor nitrogen-fixing rhizobium bacteria called bacteroids. Several legume species produce peptides called nodule-specific cysteine-rich (NCR) peptides in the symbiotic nodule cells which house the bacteroids.

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Nicotianamine (NA) is a non-protein amino acid derivative synthesized from S-adenosyl L-methionine able to bind several metal ions such as iron, copper, manganese, zinc, or nickel. In plants, NA appears to be involved in iron availability and is essential for the plant to complete its biological cycle. In graminaceous plants, NA is also the precursor in the biosynthesis of phytosiderophores.

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Background Since the identification of the genes controlling the root acquisition of iron (Fe), the control of inter- and intracellular distribution has become an important challenge in understanding metal homeostasis. The identification of the yellow stripe-like (YSL) transporter family has paved the way to decipher the mechanisms of long-distance transport of Fe. Scope Once in the plant, Fe will systematically react with organic ligands whose identity is poorly known so far.

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The two main features of plant hyper-accumulator species are the massive translocation of heavy metal ions to the aerial parts and their tolerance to such high metal concentrations. Recently, several lines of evidence have indicated a role for nicotianamine (NA) in metal homeostasis, through the chelation and transport of NA-metal complexes. The function of transport of NA-metal chelates, required for the loading and unloading of vessels, has been assigned to the Yellow Stripe 1 (YSL)-Like family of proteins.

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Plant metal hyperaccumulator species are widely used as models to unravel the heavy metal tolerance and hyperaccumulation mechanisms. Thlaspi caerulescens is capable of tolerating and hyperaccumulating Zn, Cd, and Ni. A search for factors involved in the cellular tolerance to Ni, based on yeast screens, led to isolation of a cDNA encoding a functional nicotianamine (NA) synthase (NAS).

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The metal tolerance of metal hyper-accumulating plants is a poorly understood mechanism. In order to unravel the molecular basis of zinc (Zn) tolerance in the Zn hyper-accumulating plant Arabidopsis halleri ssp. halleri, we carried out a functional screening of an A.

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Nicotianamine is a methionine derivative involved in iron homeostasis, able to bind various other metals in vitro. To investigate its role in vivo, we expressed a nicotianamine synthase cDNA (TcNAS1) isolated from the polymetallic hyperaccumulator Thlaspi caerulescens in Arabidopsis thaliana. Transgenic plants expressing TcNAS1 over-accumulated NA, up to 100-fold more than wild type plants.

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•  The cellular tolerance to nickel (Ni), zinc (Zn) and cadmium (Cd) of two poly-hyperaccumulators, Arabidopsis halleri and Thlaspi caerulescens, was investigated in order to compare their cellular phenotypes toward various metal ion exposures. •  Protoplasts were kept for 24 h on solutions containing increasing concentrations of the metal ions, and a viability test was performed. Zinc loading of the protoplasts was investigated with Arabidopsis lyrata and A.

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Thlaspi caerulescens exhibits a unique capacity for cadmium tolerance and accumulation. We investigated the molecular basis of this exceptional Cd(2+) tolerance by screening for T. caerulescens genes, which alleviate Cd(2+) toxicity upon expression in Saccharomyces cerevisiae.

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A novel analytical approach based on a combination of multidimensional hyphenated techniques and cloning of the Ni-resistance gene using yeast complementation screens was developed for the identification of nickel species in a Thlaspi caerulescens hyperaccumulating plant. The presence of an unknown strong Ni complex was demonstrated by size exclusion HPLC-capillary electrophoresis with ICPMS detection. The Ni-containing peak was characterized by electrospray MS (m/z 360) and shown by collision-induced dissociation MS to be a chelate with a tricarboxylic amino acid ligand.

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