References of "Du Jardin, Patrick"
     in
Bookmark and Share    
Peer Reviewed
See detailTowards new bioherbicides derived from barley root allelochemicals
Bouhaouel, Imen ULiege; Gfeller, Aurélie; Fauconnier, Marie-Laure ULiege et al

Conference (2015, October 09)

Detailed reference viewed: 58 (13 ULiège)
Full Text
Peer Reviewed
See detailInfluence of rhizobacterial volatiles on the root system architecture and the production and allocation of biomass in the model grass Brachypodium distachyon (L.) P. Beauv.
Delaplace, Pierre ULiege; Delory, Benjamin ULiege; Baudson, Caroline ULiege et al

in BMC Plant Biology (2015), 15(195),

Background Plant growth-promoting rhizobacteria are increasingly being seen as a way of complementing conventional inputs in agricultural systems. The effects on their host plants are diverse and include ... [more ▼]

Background Plant growth-promoting rhizobacteria are increasingly being seen as a way of complementing conventional inputs in agricultural systems. The effects on their host plants are diverse and include volatile-mediated growth enhancement. This study sought to assess the effects of bacterial volatiles on the biomass production and root system architecture of the model grass Brachypodium distachyon (L.) Beauv. Results An in vitro experiment allowing plant-bacteria interaction throughout the gaseous phase without any physical contact was used to screen 19 bacterial strains for their growth-promotion ability over a 10-day co-cultivation period. Five groups of bacteria were defined and characterised based on their combined influence on biomass production and root system architecture. The observed effects ranged from unchanged to greatly increased biomass production coupled with increased root length and branching. Primary root length was increased only by the volatile compounds emitted by Enterobacter cloacae JM22 and Bacillus pumilus T4. Overall, the most significant results were obtained with Bacillus subtilis GB03, which induced an 81% increase in total biomass, as well as enhancing total root length, total secondary root length and total adventitious root length by 88.5, 201.5 and 474.5%, respectively. Conclusions This study is the first report on bacterial volatile-mediated growth promotion of a grass plant. Contrasting modulations of biomass production coupled with changes in root system architecture were observed. Most of the strains that increased total plant biomass also modulated adventitious root growth. Under our screening conditions, total biomass production was strongly correlated with the length and branching of the root system components, except for primary root length. An analysis of the emission kinetics of the bacterial volatile compounds is being undertaken and should lead to the identification of the compounds responsible for the observed growth-promotion effects. Within the context of the inherent characteristics of our in vitro system, this paper identifies the next critical experimental steps and discusses them from both a fundamental and an applied perspective. [less ▲]

Detailed reference viewed: 173 (12 ULiège)
Full Text
Peer Reviewed
See detailRhizobacterial volatiles influence root system architecture, biomass production and allocation of the model grass Brachypodium distachyon (L.) P. Beauv.
Delaplace, Pierre ULiege; Ormeño-Lafuente, Elena; Delory, Benjamin ULiege et al

Conference (2015, June 18)

Plant growth-promoting rhizobacteria are increasingly considered as a complement of conventional inputs in agricultural systems. Their effects on their host plants are diverse and include volatile ... [more ▼]

Plant growth-promoting rhizobacteria are increasingly considered as a complement of conventional inputs in agricultural systems. Their effects on their host plants are diverse and include volatile-mediated growth enhancement. The present study aims at assessing the effects of bacterial volatile production on the biomass production and the root system architecture of Brachypodium distachyon (L.) Beauv. (line Bd-21). An in vitro experimental set-up allowing plant-bacteria interaction through the gaseous phase without any physical contact was used to screen 19 bacterial strains for their growth promotion ability over a 10-day cocultivation period. Using principal component analysis followed by hierarchical clustering and two-way analysis of variance, five groups of bacteria were defined and characterized based on their combined influence on biomass production and root system architecture. The observed effects range from unchanged to highly increased biomass production coupled with increased root length and branching. Primary root length was only increased by the volatile compounds emitted by Enterobacter cloacae JM22 and Bacillus pumilus T4. Overall, the most significant results were obtained with Bacillus subtilis GB03 which induced a 81% increase in total biomass and enhanced total root length, total secondary root length and total adventitious root length by 88, 196 and 473% respectively. The analysis of the emission kinetics of bacterial volatile organic compounds is underway and should lead to the identification of volatile compounds candidates responsible for the observed growth promotion effects. Taking into account the inherent characteristics of our in vitro system, the next experimental steps are identified and discussed from a fundamental and applied viewpoint. [less ▲]

Detailed reference viewed: 97 (11 ULiège)
Full Text
See detailImpacts of Plant Growth-Promoting Rhizobacteria on Wheat Growth under Greenhouse and Field Conditions
Nguyen, Minh ULiege; du Jardin, Patrick ULiege; Jijakli, Haissam ULiege et al

Poster (2015, June 16)

Plant Growth-Promoting Rhizobacteria (PGPR) are well-known on stimulating root growth, enhancing mineral availability, and nutrient use efficiency in crops, and therefore become promising tool for ... [more ▼]

Plant Growth-Promoting Rhizobacteria (PGPR) are well-known on stimulating root growth, enhancing mineral availability, and nutrient use efficiency in crops, and therefore become promising tool for sustainable agriculture. The aim of this project is to screen PGPR strains to enhance wheat growth and yield in combination with an optimised nitrogen (N) fertilizer dose, and thus finally reduce the use of N fertilizer with equivalent yield as the recommended N dose. A list of PGPR has been collected, including (1) Mix1 (a mix of Azospirillum sp., Azorhizobium sp., and Azoarcus sp.), (2) Mix2 (a mix of Mix1 plus with two strains phosphorus-solubilizing Bacillus sp.), (3) Bacillus amyloliquefaciens a, (4) Bacillus subtilis, and (5) Bacillus amyloliquefaciens b. The PGPR were screened in both greenhouse and field condition 2014. There was significant increase in root dry weight and in root per shoot ratio of plants inoculated with Mix1 in the greenhouse. Under field condition, besides the first factor PGPR, an additional factor, i.e. four N fertilizer doses, was applied in the combination with PGPR. Without or at low N fertilizer doses, the results showed that the grain yield declined significantly. The highest grain yield increase was fifteen per cent above the control and achieved by inoculating Bacillus subtilis without application of N fertilizer. However, there was statistically insignificant in all treatments due to variability between plot replicates. Based on these results, a modified protocol plus new strategies for PGPR selection has been built up for 2015 trial to reduce the influence of variability on field and possibly achieve the higher yield increase. [less ▲]

Detailed reference viewed: 140 (5 ULiège)
Full Text
Peer Reviewed
See detailA consensual Diving-PAM protocol to monitor Posidonia oceanica photosynthesis
Gobert, Sylvie ULiege; Lepoint, Gilles ULiege; Silva, João et al

Conference (2015, May)

The seagrass Posidonia oceanica is widely recognized as an effective bioindicator of the health status of Mediterranean coastal waters. Chlorophyll fluorescence measurements, in particular through the ... [more ▼]

The seagrass Posidonia oceanica is widely recognized as an effective bioindicator of the health status of Mediterranean coastal waters. Chlorophyll fluorescence measurements, in particular through the Pulse Amplitude Modulated (PAM) fluorometry method, are performed to study aquatic plant ecology and vitality and to assess their responses to diverse stressful factors. However, the current understanding of P. oceanica photosynthetic responses to environmental stresses does only allow scientists to use the PAM-method as a complementary tool to other more-robust monitoring techniques. Consequently, a more in-depth knowledge of the natural causes of variability of P. oceanica photosynthetic responses are a prerequisite to any surveys relying on that time and cost-effective method. In the framework of the STARECAPMED project, this work aimed to determine the influence of several environmental (depth, daytime, season) and plant-specific characteristics (leaf age, leaf part analyzed, epiphytic coverage) on the photosynthetic responses (Y, ETR, RLC) of P. oceanica. Water temperature, irradiance and several biochemical parameters of the seagrass (chl.a, chl.b, C, N, P, micronutrients such as Fe, Cu) were measured as well. The field survey was performed in a pristine meadow in the Calvi Bay, Corsica. Environmental and plant-physiological characteristics deeply influenced P. oceanica photosynthetic responses. As an example, ETR decreased with depth, contrary to Y that mostly increased. ETR was lower in the basal part of leaf blade, and the epiphytic coverage of leaf tips slightly increased their ETR compared to leaf tips cleaned of epiphytes. Depth and leaf part-related variations in RLC were also observed. Because of this natural variability, it appears essential to develop a consensual protocol of chlorophyll fluorescence measurements to publish reliable and comparable results between studies. We therefore notably suggest to perform measurements close to midday, when photosynthetic responses are the highest; at 10-15 m depth in order to avoid, among others, low depth light irradiance variability; on the middle part of the 3rd-4th external leaf, well developed, highly photosynthetic, and little epiphyted. Finally, because P. oceanica fluorescence was correlated with N, P and chl.b leaf contents, the PAM-method could afterwards be used as bioindicator technique, according to the protocol proposed. [less ▲]

Detailed reference viewed: 93 (22 ULiège)
Full Text
See detailThe CROSTVOC project – an integrated approach to study the effect of stress on BVOC exchange between agricultural crops and grassland ecosystems and the atmosphere
Amelynck, Crist; Heinesch, Bernard ULiege; Aubinet, Marc ULiege et al

in Geophysical Research Abstracts (2015, April), 17

Global changes in atmospheric composition and climate are expected to affect BVOC exchange between terrestrial vegetation and the atmosphere through changes in the drivers of constitutive BVOC emissions ... [more ▼]

Global changes in atmospheric composition and climate are expected to affect BVOC exchange between terrestrial vegetation and the atmosphere through changes in the drivers of constitutive BVOC emissions and by increases in frequency and intensity of biotic or abiotic stress episodes. Indeed, several studies indicate changes in the emission patterns of constitutive BVOCs and emission of stress-induced BVOCs following heat, drought and oxidative stress, amongst others. Relating changes in BVOC emissions to the occurrence of one or multiple stressors in natural environmental conditions is not straightforward and only few field studies have dealt with it, especially for agricultural crop and grassland ecosystems. The CROSTVOC project aims to contribute in filling this knowledge gap in three ways. Firstly, it aims at performing long-term BVOC emission field measurements from maize (Zea mays L.) and wheat (Triticum aestivum L.), two important crop species on the global scale, and from grassland. This should lead to a better characterization of (mainly oxygenated) BVOC emissions from these understudied ecosystems, allowing a better representation of those emissions in air quality and atmospheric chemistry and transport models. BVOC fluxes are obtained by the Disjunct Eddy Covariance by mass scanning (DEC-MS) technique, using a hs-PTR-MS instrument for BVOC analysis. Secondly, the eddy covariance BVOC flux measurements (especially at the grassland site) will be accompanied by ozone flux, chlorophyll fluorescence, photosynthesis and soil moisture measurements, amongst others, to allow linking alterations in BVOC emissions to stress episodes. Simultaneously, automated dynamic enclosures will be deployed in order to detect specific abiotic and biotic stress markers by PTR-MS and identify them unambiguously by GC-MS. Thirdly, the field measurements will be accompanied by laboratory BVOC flux measurements in an environmental chamber in order to better disentangle the responses of the BVOC emissions to driving factors that co-occur in field conditions and to determine the influence of single abiotic stressors on BVOC emissions. Next to a general presentation, some preliminary results of the project will be shown. [less ▲]

Detailed reference viewed: 200 (23 ULiège)
Full Text
See detailBiogenic Volatile Organic Compound (BVOC) emissions from agricultural crop species: is guttation a possible source for methanol emissions following light/dark transition?
Mozaffar, Ahsan ULiege; Amelynck, Crist; Bachy, Aurélie ULiege et al

in Geophysical Research Abstracts (2015, April), 17(EGU2015-2110-1),

In the framework of the CROSTVOC (CROp STress VOC) project, the exchange of biogenic volatile organic compounds (BVOCs) between two important agricultural crop species, maize and winter wheat, and the ... [more ▼]

In the framework of the CROSTVOC (CROp STress VOC) project, the exchange of biogenic volatile organic compounds (BVOCs) between two important agricultural crop species, maize and winter wheat, and the atmosphere has recently been measured during an entire growing season by using the eddy covariance technique. Because of the co-variation of BVOC emission drivers in field conditions, laboratory studies were initiated in an environmental chamber in order to disentangle the responses of the emissions to variations of the individual environmental parameters (such as PPFD and temperature) and to diverse abiotic stress factors. Young plants were enclosed in transparent all-Teflon dynamic enclosures (cuvettes) through which BVOC-free and RH-controlled air was sent. BVOC enriched air was subsequently sampled from the plant cuvettes and an empty cuvette (background) and analyzed for BVOCs in a high sensitivity Proton-Transfer Reaction Mass Spectrometer (hs-PTR-MS) and for CO2 in a LI-7000 non-dispersive IR gas analyzer. Emissions were monitored at constant temperature (25 °C) and at a stepwise varying PPFD pattern (0-650 µmol m-2 s-1). For maize plants, sudden light/dark transitions at the end of the photoperiod were accompanied by prompt and considerable increases in methanol (m/z 33) and water vapor (m/z 39) emissions. Moreover, guttation droplets appeared on the sides and the tips of the leaves within a few minutes after light/dark transition. Therefore the assumption has been raised that methanol is also coming out with guttation fluid from the leaves. Consequently, guttation fluid was collected from young maize and wheat plants, injected in an empty enclosure and sampled by PTR-MS. Methanol and a large number of other compounds were observed from guttation fluid. Recent studies have shown that guttation from agricultural crops frequently occurs in field conditions. Further research is required to find out the source strength of methanol emissions by this guttation phenomenon in real environmental conditions. [less ▲]

Detailed reference viewed: 173 (10 ULiège)
Full Text
See detailInterdire des OGM autorisés : on avance ou on recule ?
du Jardin, Patrick ULiege

Article for general public (2015)

Detailed reference viewed: 82 (12 ULiège)
Full Text
Peer Reviewed
See detailBiotechnological uses of RNAi in plants: Risk assessment considerations
Casacuberta, J. M.; Devos, Y.; du Jardin, Patrick ULiege et al

in Trends in Biotechnology (2015), 33(3), 145-147

RNAi offers opportunities to generate new traits in genetically modified (GM) plants. Instead of expressing novel proteins, RNAi-based GM plants reduce target gene expression. Silencing of off-target ... [more ▼]

RNAi offers opportunities to generate new traits in genetically modified (GM) plants. Instead of expressing novel proteins, RNAi-based GM plants reduce target gene expression. Silencing of off-target genes may trigger unintended effects, and identifying these genes would facilitate risk assessment. However, using bioinformatics alone is not reliable, due to the lack of genomic data and insufficient knowledge of mechanisms governing mRNA-small (s)RNA interactions. © 2014 Elsevier Ltd. [less ▲]

Detailed reference viewed: 100 (2 ULiège)
Full Text
Peer Reviewed
See detailPlant biostimulants: Definition, concept, main categories and regulation
du Jardin, Patrick ULiege

in Scientia Horticulturae (2015)

Detailed reference viewed: 139 (5 ULiège)
Full Text
Peer Reviewed
See detailNext-generation sequencing as a tool for the molecular characterisation and risk assessment of genetically modified plants: Added value or not ?
Pauwels, Katia; De Keersmaecker, Sigrid; De Schrijver, Adinda et al

in Trends in Food Science & Technology (2015), 45

Detailed reference viewed: 55 (0 ULiège)
Full Text
Peer Reviewed
See detailAllelopathic and autotoxicity effects of barley (Hordeum vulgare L. ssp. vulgare) root exudates
Bouhaouel, Imen; Gfeller, Aurélie; Fauconnier, Marie-Laure ULiege et al

in BioControl (2014), Online First

The allelopathic activity of barley (Hordeum vulgare L. ssp. vulgare) root exudates was studied by comparing their effects on seedling establishment in barley itself and in two weed species, Bromus ... [more ▼]

The allelopathic activity of barley (Hordeum vulgare L. ssp. vulgare) root exudates was studied by comparing their effects on seedling establishment in barley itself and in two weed species, Bromus diandrus Roth. and Lolium rigidum Gaudin, using an original laboratory protocol, named ‘seed-after-seed’. In this protocol, the donor and the receiver species of watersoluble allelochemicals are grown one after the other in the same dishes, in conditions reducing resource competition between both species. Growth of all receptive species (weeds and barley) was inhibited in a dose-dependent manner, when using increasing barley seed densities (0, 8, 19 and 25 seeds per Petri dish). In our conditions, the barley varieties and landraces exhibited different allelopathic activities against weeds or barley. The allelopathic potential of the barley root exudates was also dependent on the receiver species. Indeed, the released allelochemicals proved to be more toxic against the weed plants than on barley itself. Furthermore, the toxicity of the allelochemicals increased after their release by roots, between day 0 and day 6. These allelochemicals might contribute to the plant community dynamics and their usefulness as bio-herbicides deserves further consideration. [less ▲]

Detailed reference viewed: 68 (15 ULiège)
Full Text
See detailImpacts of biostimulant products on the growth of wheat and the microbial communities of its rhizosphere under contrasted production systems
Nguyen, Minh ULiege; Bodson, Bernard ULiege; Colinet, Gilles ULiege et al

Poster (2014, August 24)

Plant growth-promoting rhizobacteria (PGPR) are one of the major biostimulant classes due to their ability to stimulate root growth, enhance mineral availability, and nutrient use efficiency in crops ... [more ▼]

Plant growth-promoting rhizobacteria (PGPR) are one of the major biostimulant classes due to their ability to stimulate root growth, enhance mineral availability, and nutrient use efficiency in crops. PGPR-containing biostimulant products could therefore make agriculture more sustainable by reducing demand for chemical fertilizer and lessen their negative environmental impacts. The aim of this project is to screen PGPR strains to (1) enhance wheat fitness level (growth, photosynthesis efficiency, stress tolerance, and yield) in combination with an optimised fertilizer level, (2) stimulate the increase in beneficial microorganism communities and suppress pathogenic ones in the wheat rhizosphere, (3) link wheat productivity to the composition of the microbial communities found in its rhizosphere, and (4) measure the impacts of such changes on soil fertility. A list of PGPR-containing biostimulants have been collected from screening, including several commercially available products (e.g. TwinN and NitroGuard, Mabiotec; Rhizocell GC, Ithec; B. subtilis FZB24 fl and Rhizo Vital 42, Abitep) as well as newly discovered PGPR strains. The biostimulants from that list have been screened in greenhouse and we expect to obtain results within next month. In parallel, several levels of nitrogen supply have been tested in combination with biostimulants to optimize agricultural practices and achieve the highest yield on field condition. A soil analysis protocols will also be built up to measure the influence of those PGPR strains on soil fertility changes and root uptake efficiency. In order to assess changes in the rhizomicrobial communities including fungi and bacteria (either pathogenic, neutral, or beneficial) under controlled or field conditions, metagenomic approaches will be set up. Finally, a maximum of three promising PGPR strains will be selected for practical agronomical application in larger field trials. [less ▲]

Detailed reference viewed: 111 (8 ULiège)
Peer Reviewed
See detailBarley (Hordeum distichon L.) roots produce volatile aldehydes via the lipoxygenase/hydroperoxide lyase pathway with a strong age-dependent pattern
Delory, Benjamin ULiege; Delaplace, Pierre ULiege; du Jardin, Patrick ULiege et al

Conference (2014, August 13)

In chemical ecology, the roles played by root-emitted volatile organic compounds (VOCs) in biotic interactions and the quantitative analysis of such chemicals in root tissues remain poorly documented. In ... [more ▼]

In chemical ecology, the roles played by root-emitted volatile organic compounds (VOCs) in biotic interactions and the quantitative analysis of such chemicals in root tissues remain poorly documented. In this context, this study aims at using a fully automated gas chromatography – mass spectrometry methodology allowing both identification and accurate quantification of VOCs produced by roots of a monocotyledonous plant species at five selected developmental stages from germination to the end of tillering. Results show that barley roots mainly produce four volatile aldehydes, namely hexanal, (E)-hex-2-enal, (E)-non-2-enal and (E,Z)-nona-2,6-dienal. These molecules are well-known linoleic and linolenic acid derivatives produced via the lipoxygenase/hydroperoxide lyase pathway of higher plants. Our findings contrast with analyses documented on aboveground barley tissues that mainly emit C6 aldehydes, alcohols and their corresponding esters. Multivariate statistical analyses performed on individual VOC concentrations indicate quantitative changes in the volatile profile produced by barley roots according to plant age. Barley roots produced higher total and individual VOC concentrations when young seminal roots emerged from the coleorhizae compared to older phenological stages. Moreover, results also show that the C6/C9 volatile aldehyde ratio was the lowest at the end of tillering while the maximum mean value of this ratio was reached in seven day-old barley roots. [less ▲]

Detailed reference viewed: 195 (92 ULiège)
Peer Reviewed
See detailAllo- and autoinhibition in barley and great brome: a laboratory study
Bouhaouel, Imen ULiege; Gfeller, Aurélie; Fauconnier, Marie-Laure ULiege et al

Conference (2014, February 08)

Detailed reference viewed: 68 (25 ULiège)
Peer Reviewed
See detailDevelopment of an ex-vitro system allowing plant-bacteria interactions through VOCs in the context of water stress
Mendaluk, Magdalena ULiege; Baudson, Caroline ULiege; Delory, Benjamin ULiege et al

Poster (2014, February 07)

Water stress is one of the major environmental factors limiting the crop productivity . Plant stress responses are very complex and drought tolerance may be linked to the presence of specific ... [more ▼]

Water stress is one of the major environmental factors limiting the crop productivity . Plant stress responses are very complex and drought tolerance may be linked to the presence of specific microorganisms in the rhizosphere. Indeed, some plant growth promoting bacteria (PGPR) strains have been found to improve plant growth under abiotic stresses. Among the many mechanisms by which those PGPR can support plant growth, the emission of volatile organic compounds (VOCs) and their biological impact are still under study. The aim of this work is to evaluate the interaction between the model grass Brachypodium distachyon (Bd21) and two strains of PGPR. The impact of volatile emission on Bd21 growth was studied using an ex-vitro cocultivation system without physical contact between plant and bacteria during 10 days. This peculiar system was developed to assess bacterial VOCs impacts on plants under realistic growth and stress conditions. In parallel, the response of Bd21 seedlings to water deficit induced by polyethylene glycol 6000 (PEG 6000) was studied to establish contrasted growth conditions regarding water availability [less ▲]

Detailed reference viewed: 70 (3 ULiège)