Claude Plassard

Claude Plassard
INRA Montpellier · Ecologie Fonctionnelle & Biogéochimie des sols & des Agroécosystèmes (Eco&Sols)

PhD in plant sciences

About

120
Publications
34,399
Reads
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5,214
Citations
Citations since 2016
38 Research Items
3035 Citations
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
20162017201820192020202120220100200300400500
Additional affiliations
January 1986 - present
INRA Montpellier
Position
  • Dr, Co-leader of a research group group studying the interactions between organisms in the root environment
Description
  • Ectomycorrhizal functioning, N and P uptake, bacterial grazing and mineral nutrition of trees.

Publications

Publications (120)
Article
Full-text available
Bacterial-feeding nematodes are abundant soil animals regulating microbial communities and enhancing plant nutrition and growth. However, the biological metrics driving the variable within-trophic group effects of these organisms on soil and plant functions are not yet identified. In this study, we determined the effects of eight bacterial-feeding...
Article
Full-text available
Eucalyptus is the tree most widely planted in tropical countries to satisfy growing demand for wood products, but high yields require high fertilizer inputs. Introducing N2-fixing trees (NFT), such as Acacia mangium, has been proposed to improve soil fertility and aboveground tree biomass in Eucalyptus plantations. In addition to N inputs, NFT spec...
Chapter
Mycorrhizal plants dominate in most ecosystems and they differ in belowground carbon allocation, capacity of organic nutrient acquisition, impact on soil carbon, and nutrient cycling. So far, to improve our understanding of mycorrhizal contributions to soil C and nutrient cycling, most research has been carried out in very different biomes (e.g., a...
Article
Full-text available
Agricultural practices significantly affect soil biodiversity and functions, altering biogeochemical cycles and potentially compromising food production. Increased employment of sustainable agricultural practices is of growing policy concern and requires a better understanding and quantification of how agriculture affects soil functioning. We condu...
Article
Plant diversification through crop rotation or agroforestry is a promising way to improve sustainability of agroecosystems. Nonetheless, criteria to select the most suitable plant communities for agroecosystems diversification facing contrasting environmental constraints need to be refined. Here, we compared the impacts of 24 different plant commun...
Article
Full-text available
Free-living nematodes have beneficial effects on plant growth and nutrition. Exploring how agricultural practices modulate these beneficial effects is still challenging. A study was conducted in Ferralsols from Madagascar from one unmanaged grassland and 16 upland rainfed rice fields, representative of different agricultural practices: rotation, ag...
Article
A new myo-inositol pentakisphosphate was synthesized, which featured a dansyl group at position C-5. The fluorescent tag was removed from the inositol by a 6-atom spacer to prevent detrimental steric interactions in the catalytic site of phytases. The PEG linker was used in order to enhance hydrophilicity and biocompatibility of the new artificial...
Article
Full-text available
The microbial loop has been suggested as an alternative route for better utilization of phytate, a poorly available P source to plants. We hypothesized that bacterial grazer activity might dramatically enhance bacterial migration and proliferation, increasing the probability of phytate hydrolysis by bacterial phytases and, thus, phytate mineralizat...
Article
Full-text available
Plants evolve complex interactions with diverse soil mutualist organisms to enhance P mobilization from the soil. These strategies are particularly important when P is poorly available. It is still unclear how the soil P source (e.g., mineral P versus recalcitrant organic P) and its mobility in the soil (high or low) affect soil mutualist biologica...
Article
Soil aggregates are critical to soil functionality, but there remain many uncertainties with respect to the role of biotic factors in forming aggregates. Understanding the interacting effects of soil, land use type, vegetation and microbial communities is a major challenge that needs assessment in both field and controlled laboratory conditions, as...
Article
Full-text available
Background & Aims Better understanding of belowground interactions in agroforestry systems is crucial for the success of plant co-existence. Beyond root competition, associated arbuscular mycorrhizal (AM) fungi can also be involved in plant to plant interactions. Thus far, the contribution of each agroforestry component (trees, herbaceous vegetatio...
Article
Many studies have shown that introducing N2-fixing trees (e.g. Acacia mangium) in eucalypt plantations can increase soil N availability as a result of biological N2 fixation and faster N cycling. Some studies have also shown improved eucalypt P nutrition. However, the effects of N2-fixing trees on P cycling in tropical soils remain poorly understoo...
Article
The concept of soil nutrient availability is still widely viewed within the framework of crop yield responses to fertilizer applications as the intermediary variable linking the rate of application of a single nutrient to the absorption of this nutrient by plants according to the pioneer work of Boussingault (1855), von Liebig (1855), and Mitscherl...
Article
Phytate is considered a poorly available plant P source but proved to be useful for particular soil bacteria strains. In soil-free conditions, it has been shown that bacteria locked up the mineralized phosphorus from phytate whereas bacterial grazers like nematodes were able to deliver P to plants. Here, we aimed to determine if the interactions be...
Article
Full-text available
Despite the strong ecological importance of ectomycorrhizal (ECM) fungi, their vertical distribution remains poorly understood. To our knowledge, ECM structures associated with trees have never been reported in depths below 2 meters. In this study, fine roots and ECM root tips were sampled down to 4-m depth during the digging of two independent pit...
Article
Mycorrhizal fungi considerably improve plant nutrition and help them to cope with changing environments. Particularly, these fungi express proteins to transfer actively inorganic phosphate (Pi) from the soil to colonized roots through symbiotic interfaces. The mechanisms involved in Pi transfer from fungal to plant cells are still largely unknown....
Article
Functional specialization of fine roots was found for Eucalyptus grandis trees at harvesting age (6 years) on tropical soils. Aiming to elucidate whether functional specialization is a ubiquitous feature of eucalypts, we focused on its changes with ontogeny, tree nutrient status and soil depth. We studied the potential uptake of N, K and Ca by 2-ye...
Article
Ectomycorrhizal fungi improve tree phosphorus nutrition through transporters specifically localized at soil-hyphae and symbiotic interfaces. In the model symbiosis between the fungus Hebeloma cylindrosporum and the maritime pine (Pinus pinaster), several transporters possibly involved in phosphate fluxes were identified, including three H⁺:Pi trans...
Article
We used in vivo and in vitro phosphorus-31 nuclear magnetic resonance (31P-NMR) spectroscopy to follow the change in transport, compartmentation and metabolism of phosphate in the ectomycorrhizal fungus Hebeloma cylindrosporum in response to root signals originating from host (Pinus pinaster) or non-host (Zea mays) plants. A device was developed fo...
Article
Soil bacterivorous nematodes are key plant mutualists that increase nutrient availability for plants either by enhancing the mineralization of organic compounds (the “mineralization pathway”) or by increasing plant lateral root branching following shifts in internal plant metabolism, and subsequently leading to a higher volume of soil prospected by...
Article
Full-text available
Through a mutualistic relationship with woody plant roots, ectomycorrhizal fungi provide growth-limiting nutrients, including inorganic phosphate (Pi), to their host. Reciprocal trades occur at the Hartig net, which is the symbiotic interface of ectomycorrhizas where the two partners are symplasmically isolated. Fungal Pi must be exported to the sy...
Article
Full-text available
I. II. III. IV. V. VI. VII. References Nutrient homeostasis is essential for fungal cells and thus tightly adapted to the local demand in a mycelium with hyphal specialization. Based on selected ectomycorrhizal (ECM) fungal models, we outlined current concepts of nitrogen and phosphate nutrition and their limitations, and included knowledge from Ba...
Article
Full-text available
Soil bacterivorous nematodes are key plant mutualists that increase nutrient availability for plants either by enhancing the mineralization of organic compounds (the "mineralization pathway") or by increasing plant lateral root branching following shifts in internal plant metabolism, and subsequently leading to a higher volume of soil prospected by...
Article
In ectomycorrhizal plants, the fungal cells colonize the roots of their host plant to create new organs called ectomycorrhizae. In these new organs, the fungal cells colonize the walls of the cortical cells, bathing in the same apoplasm as the plant cells in a space named the ‘Hartig net’, where exchanges between the two partners take place. Finall...
Article
] In order to quantify P accumulation and P efflux in the ectomycorrhizal basidiomycete fungus Hebeloma cylindrosporum, we supplied 32 P to mycelia previously grown in vitro in liquid medium. The culture had four main steps that are 1) growing the mycelium on complete medium with P, 2) transfer the mycelia into new culture solution with or without...
Article
We tested the ability of root-adhering soils (RAS) from eight rice cultivars to attract a bacterivorous nematode (Acrobeloides sp.) living in a poor-nutrient soil in Madagascar. We showed that the ability of rice to attract bacterivorous nematodes in its rhizosphere is variable among cultivars. FOFIFA 172 was the cultivar with the highest attractio...
Book
La production agricole dépend, entre autres, d’une bonne nutrition minérale en macro-éléments comme l’azote (N), le phosphore (P), le souffre (S) et le potassium (K) des cultures. Plus spécifiquement, l’alimentation en N et P des végétaux est majoritairement assurée par la fertilisation minérale qui apporte les ions minéraux qui pourront être absor...
Article
1. Characterizing the ecological processes driving the assembly and functional composition of ectomycorrhizal (ECM) fungal communities is an area of active research. 2. Here, we applied a trait-based framework to address whether and how environmental filtering and niche differentiation influence the diversity of ECM fungal enzymatic activities in...
Article
Full-text available
Ectomycorrhizal (ECM) association can improve plant phosphorus (P) nutrition. Polyphosphates (polyP), synthesized in distant fungal cells after P uptake may contribute to P supply from the fungus to the host plant if they are hydrolyzed to phosphate in ECM roots then transferred to the host plant when required. In this study, we addressed this hypo...
Article
Full-text available
Background Bacterivores, mostly represented by protists and nematodes, are a key component of soil biodiversity involved in soil fertility and plant productivity. In the current context of global change and soil biodiversity erosion, it becomes urgent to suitably recognize and quantify their ecological importance in ecosystem functioning.ScopeUsing...
Article
Full-text available
Dispersion of bacterivorous nematodes in soil is a crucial ecological process that permits settlement and exploitation of new bacterial-rich patches. Although plant roots, by modifying soil structure, are likely to influence this process, they have so far been neglected. In this study, using an original three-compartment microcosm experimental desi...
Chapter
Full-text available
Phosphorus (P) occurs at low concentrations in soils because of the numerous processes responsible for P sorption or immobilisation. Soil P is also characterised by its restricted mobility, and thus the most limiting step of P acquisition is not its absorption by plant roots, but rather the many processes that determine the fate of soil P in the rh...
Article
Full-text available
An optimized method, based on the coupling of two commercial kits, is described for the extraction of soil nucleic acids, with simultaneous extraction and purification of DNA and RNA following a cascade scheme and avoiding the use of harmful solvents. The protocol canmonitor the variations in the recovery yield of DNA and RNA from soils of various...
Article
Full-text available
Les ions orthophosphates (Pi) représentent les seules formes de phosphore (P) utilisable par les cultures. Dans les sols, ils sont généralement présents à de faibles concentrations dans la solution, en raison des nombreux processus géochimiques contraignant leur mobilité et disponibilité. Les plantes et les micro-organismes associés, au travers de...
Book
Phosphorus (P) occurs at low concentrations in soils because of the numerous processes responsible for P sorption or immobilisation. Soil P is also characterised by its restricted mobility, and thus the most limiting step of P acquisition is not its absorption by plant roots, but rather the many processes that determine the fate of soil P in the rh...
Conference Paper
Full-text available
Many field observations suggest that ECM contribute to a number of key ecosystem functions such as carbon cycling, nutrient mobilization from soil organic matter and soil minerals, providing a link between trees through common mycorrhizal networks. In Brazil, the ECM form symbiotic associations with species of great economic importance, belonging t...
Article
Full-text available
Phosphorus (P) is one of the main nutrients required for plant growth and is absorbed and metabolized in the form of orthophosphate ions (Pi). In agriculture, P is a major component of fertilizers. Forecast shortages in P mine stocks within the coming decades call for alternative sources of this element for agricultural use. In the present study, w...
Article
Full-text available
Phosphorus(P)isessentialforplantgrowthandproductivity.Itisoneofthemostlimitingmacronutrientsinsoilbecauseitismainlypresentasunavailable,boundPwhereasplantscanonlyuseunbound,inorganicphosphate(Pi),whichisfoundinverylowconcentrationsinsoilsolution.Someectomycorrhizalfungiareabletoreleaseorganiccompounds(organicanionsorphosphatases)tomobilizeunavailab...
Conference Paper
Phosphorus from inorganic sources such as tricalcium P (rock phosphate), though constitutes the major proportion in soils of lower Himalaya regions of Pakistan, is mainly unavailable to plants. The need of available P in this zone, is deteriorating the natural ecosystem of the area via environmental pollution through mining and artificial P fertili...
Conference Paper
Phosphorus (P) strongly limits plant productivity as plants can only absorb free inorganic orthophosphate (Pi) at very low concentrations in soil solution. However, soil contains high levels of poorly available P, especially phytate, considered as the most abundant plantunavailable organic P source. Here, we investigated a new strategy based on rhi...
Article
Full-text available
Background and aims Intercropping of legumes and cereals appears as an alternative agricultural practice to decrease the use of chemical fertilizers while maintaining high yields. A better understanding of the biotic and abiotic factors determining interactions between plants in such associations is required. Our study aimed to analyse the effect o...
Article
Nutrient availability, particularly phosphorus (P), and water are major factors limiting tree growth in plantations of maritime pine (Pinus pinaster) in southwestern France. Applied intensively, fertilization and irrigation could have differential effects on the actual nutrient availability to the trees, especially P. These practices could modify t...
Article
Full-text available
Soil organic phosphorus (Po) such as phytate, which comprises up to 80 % of total Po, must be hydrolyzed by specific enzymes called phytases to be used by plants. In contrast to plants, bacteria, such as Bacillus subtilis, have the ability to use phytate as the sole source of P due to the excretion of a beta-propeller phytase (BPP). In order to ass...
Article
Full-text available
Mycorrhizal associations are known to improve the hydro-mineral nutrition of their host plants. However, the importance of mycorrhizal symbiosis for plant potassium nutrition has so far been poorly studied. We therefore investigated the impact of the ectomycorrhizal fungus Hebeloma cylindrosporum on the potassium nutrition of Pinus pinaster and exa...
Article
Full-text available
Bacillus sp. strain CaSUT007, a plant growth promoting rhizobacterium isolated from cassava, was investigated for the secretion of compounds that might be involved in plant growth promotion. Extracts containing phytohormone and extracellular proteins were made from the cell-free fluid of CaSUT007 broth cultures. These extracts, along with a whole c...
Article
Full-text available
In the mediterranean region, the strong edaphic, climatic and economic constraints lead to the increase of the transplantation crisis of young trees. The use of controlled mycorrhizal infection is one of the means open to reduce the effects of this crisis by improving the quality of the forest trees grown in nursery, and the reforestation. To achie...
Article
Full-text available
The microbial loop based on the grazing of bacteria by bacterial-feeding nematodes is thought to play a major role in the mineralization of nutrients such as nitrogen (N) and phosphorus (P) in terrestrial ecosystems. This study was undertaken to quantify the effect of bacterial grazing nematodes on root architecture, growth and mineral nutrition (N...
Article
Full-text available
Background and aims Phosphorus from phytate, although constituting the main proportion of organic soil P, is unavailable to plants. Despite the well-known effects of rhizosphere trophic relationships on N mineralization, no work has been done yet on P mineralization. We hypothesized that the interactions between phytate-mineralizing bacteria, mycor...
Article
The improvement of common bean production requires the selection of effective rhizobia strains and Phaseolus vulgaris genotypes adapted to available soil phosphorus limitations. The interactions between bean genotypes and rhizobia were studied in hydroponic culture using six genotypes and four strains, CIAT899 as reference and three strains isolate...
Article
Full-text available
Background In the context of increasing global food demand, ecological intensification of agroecosystems is required to increase nutrient use efficiency in plants while decreasing fertilizer inputs. Better exploration and exploitation of soil resources is a major issue for phosphorus, given that rock phosphate ores are finite resources, which are...
Article
The microbial loop is thought to play a major role in the mineralization of nutrients such as nitrogen (N) and phosphorus (P) in terrestrial ecosystems. This microbial loop is based on the grazing of bacteria by predators such as bacterial-feeding nematodes. However, little is known about the impact of grazing by nematodes on the mineral nutrition...