Coriander (Coriandrum sativum L.) in Combination with Organic Amendments and Arbuscular Mycorrhizal Inoculation: An Efficient Option for the Phytomanagement of Trace Elements-Polluted Soils

The cultivation of coriander (Coriandrum sativum L.) destined for essential oils production was recently presented as an innovative and economically viable alternative for the phytomanagement of trace elements (TE)-polluted soils. However, Cd accumulation in shoots has proven to be an obstacle in the valorization of the distillation residues and the development of these phytotechnologies. The present study aimed to evaluate the effect of arbuscular mycorrhizal fungus (Funneliformis mosseae) inoculation and organic amendment application on the soil TE bioavailability and plant uptake, as well as on the soil quality and health improvement. The application of compost and sewage sludge improved the growth of coriander and Cd and Zn immobilization in soil, resulting in reduced Cd plant uptake. A synergistic effect of arbuscular mycorrhizal fungi (AMF) inoculation and organic amendments was observed in the decrease in the extractable soil Cd and Zn concentrations, but not in the Cd plant uptake. Despite a significant decrease in Cd accumulation in shoots, coriander retained its accumulative phenotype, with a metal bioconcentration factor close to 1. Furthermore, both the vegetation and the organic amendments improved the soil quality and health by increasing its microbial biomass, as estimated by phospholipid fatty acids, soil enzyme activities (dehydrogenase, phosphatase, β-glucosidase, and cellubiosidase), and the bacterial metabolic function and diversity. The findings demonstrate the potential of C. sativum, particularly in combination with organic amendments and AMF inoculation, for the phytomanagement of TE-polluted soils and soil quality and health improvement

Arabidopsis BNT1, an atypical TIR–NBS–LRR gene, acting as a regulator of the hormonal response to stress

International audienceDuring their life cycle, plants have to cope with fluctuating environmental conditions. The perception of the stressful environmental conditions induces a specific stress hormone signature specifying a proper response with an efficient fitness. By reverse genetics, we isolated and characterized a novel mutation in Arabidopsis, associated with environmental stress responses, that affects the At5g11250/BURNOUT1 (BNT1) gene which encode a Toll/Interleukin1 receptor-nucleotide binding site leucine-rich repeat (TIR-NBS-LRR) protein. The knock-out bnt1 mutants displayed, in the absence of stress conditions, a multitude of growth and development defects, suchas severe dwarfism, early senescence and flower sterility, similar to those observed in vitro in wild type plants upon different biotic and/or abiotic stresses. The disruption of BNT1 causes also a drastic increase of the jasmonic, salicylic and abscisic acids as well as ethylene levels. Which was consistent with the expression pattern observed in bnt1 showing an over representation of genes involved in the hormonal response to stress? Therefore, a defect in BNT1 forced the plant to engage in an exhausting general stress response, which produced frail, weakened and poorly adapted plants expressing "burnout" syndromes. Furthermore, by in vitro phenocopying experiments, physiological, chemical and molecular analyses, we propose that BNT1 could represent a molecular link between stress perception and specific hormonal signature

Relations entre diversité microbienne et contamination métallique dans des sols industriels

National audienceCette étude porte sur des sols forestiers entourant un site ayant une longue histoire industrielle métallurgique, effectuant actuellement le recyclage de batteries au plomb (Pb) et ayant eu par le passé une activité de seconde fusion du fer. L’objectif est de connaître les relations entre la contamination des sols en Pb et autres éléments-traces métalliques et les communautés microbiennes des sols. Des échantillons ont été prélevés dans trois types de sol et de couvert végétal (conifères et feuillus) et dans des zones de contamination métallique variable déterminées par mesures de fluorescence X in-situ (0-5 cm et 5-10 cm de profondeur). Des analyses pédologiques et géochimiques complémentaires ont été réalisées en laboratoire. La biomasse microbienne a été déterminée par extraction et quantification sur gel d’ADN total du sol. La diversité microbienne a été déterminée par extraction, amplification et séquençage de différentes régions codantes et non-codantes des gènes ribosomiques : une région de l’ADNr-16S (région V3-V4) pour la diversité des bactéries et une région inter-transcrits (ITS1) pour la diversité des champignons. Les résultats montrent une diversité microbienne importante, y compris dans les échantillons très contaminés, ainsi qu’une dépendance forte de certains groupes microbiens à la teneur en métaux, mais aussi au type de sol