Papers by Emmanuelle Personeni
Physiologia Plantarum
Root exudation is involved in the recruitment of beneficial microorganisms by trophic relationshi... more Root exudation is involved in the recruitment of beneficial microorganisms by trophic relationships and/or signalling pathways. Among beneficial microorganisms, Plant Growth‐Promoting Rhizobacteria (PGPR) are known to improve plant growth and stress resistance. These interactions are of particular importance for species that do not interact with mycorrhizal fungi, such as rapeseed (Brassica napus L.) and camelina (Camelina sativa (L.) Crantz). However, heat stress is known to have a quantitative and qualitative impact on root exudation and could affect the interactions between plants and PGPR. We aimed to analyse the effects of PGPR inoculation on root morphology and exudation in rapeseed and camelina at the reproductive stage. The modulation of the effects of these interactions under heat stress was also investigated. The plants were inoculated twice at the reproductive stage with two different Pseudomonas species and were exposed to heat stress after the second inoculation. In non...
Applied Soil Ecology, Feb 1, 2016
Plant species influence soil microbial communities, mainly through their functional traits. Howev... more Plant species influence soil microbial communities, mainly through their functional traits. However, mechanisms underlying these effects are not well understood, and in particular how plant/ microorganism interactions are affected by plant identities and/or environmental conditions. Here, we performed a greenhouse experiment to assess the effects of three plant species on arbuscular mycorrhizal fungal (AMF) colonization, bacterial potential nitrification (PNA) and denitrification activities (PDA) through their functional traits related to nitrogen acquisition and turnover. Three species with contrasting functional traits and strategies (from exploitative to conservative), Dactylis glomerata (L.), Bromus erectus (Hudson) and Festuca paniculata (Schinz and Tellung), were cultivated in monocultures on soil grassland with or without N fertilization. Fertilization impacted some plant traits related to nutrient cycling (leaf and root N concentration, root C:N) but did not affect directly microbial parameters. The highest PDA and PNA were observed in D. glomerata and F. paniculata monocultures, respectively. The highest AMF colonization was obtained for F. paniculata, while B. erectus exhibited both the lowest AMF colonization and bacterial activities. Bacterial activities were influenced by specific above-ground plant traits across fertilization treatments: above-ground biomass for PDA, shoot:root ratio and leaf C:N ratio for PNA. Mycorrhizal colonization was influenced by below-ground traits either root dry matter content or root C:N. Hence, AMF colonization and bacterial activities were impacted differently by species-specific plant biomass allocation, root traits and nutrient requirement. We suggest that such effects may be linked to distinct root exudation patterns and plant abilities for nutrient acquisition and/or nutrient competition.
Environmental and Experimental Botany
HAL (Le Centre pour la Communication Scientifique Directe), 2003
Residual maximum likelihood (REML) results of the influence of plant traits (physiological and be... more Residual maximum likelihood (REML) results of the influence of plant traits (physiological and belowground and whole plant traits), as explanatory factors on key microbial parameters (DEA and NEA) in adherent soil.
Plant position on the conservative vs. exploitative plants gradient in unfertilized and adherent ... more Plant position on the conservative vs. exploitative plants gradient in unfertilized and adherent soil data.
The effect of plants and fertilization on soil parameters in adherent soil (NO3- and NH4+ concent... more The effect of plants and fertilization on soil parameters in adherent soil (NO3- and NH4+ concentrations).
doi:10.1093/jxb/erp303 This paper is available online free of all access charges (see
Applied Soil Ecology, 2016
Plant species influence soil microbial communities, mainly through their functional traits. Howev... more Plant species influence soil microbial communities, mainly through their functional traits. However, mechanisms underlying these effects are not well understood, and in particular how plant/ microorganism interactions are affected by plant identities and/or environmental conditions. Here, we performed a greenhouse experiment to assess the effects of three plant species on arbuscular mycorrhizal fungal (AMF) colonization, bacterial potential nitrification (PNA) and denitrification activities (PDA) through their functional traits related to nitrogen acquisition and turnover. Three species with contrasting functional traits and strategies (from exploitative to conservative), Dactylis glomerata (L.), Bromus erectus (Hudson) and Festuca paniculata (Schinz and Tellung), were cultivated in monocultures on soil grassland with or without N fertilization. Fertilization impacted some plant traits related to nutrient cycling (leaf and root N concentration, root C:N) but did not affect directly microbial parameters. The highest PDA and PNA were observed in D. glomerata and F. paniculata monocultures, respectively. The highest AMF colonization was obtained for F. paniculata, while B. erectus exhibited both the lowest AMF colonization and bacterial activities. Bacterial activities were influenced by specific above-ground plant traits across fertilization treatments: above-ground biomass for PDA, shoot:root ratio and leaf C:N ratio for PNA. Mycorrhizal colonization was influenced by below-ground traits either root dry matter content or root C:N. Hence, AMF colonization and bacterial activities were impacted differently by species-specific plant biomass allocation, root traits and nutrient requirement. We suggest that such effects may be linked to distinct root exudation patterns and plant abilities for nutrient acquisition and/or nutrient competition.
Ecology, 2015
It has long been recognized that plant species and soil microorganisms are tightly linked, but un... more It has long been recognized that plant species and soil microorganisms are tightly linked, but understanding how different species vary in their effects on soil is currently limited. In this study, we identified those plant characteristics (identity, specific functional traits, or resource acquisition strategy) that were the best predictors of nitrification and denitrification processes. Ten plant populations representing eight species collected from three European grassland sites were chosen for their contrasting plant trait values and resource acquisition strategies. For each individual plant, leaf and root traits and the associated potential microbial activities (i.e., potential denitrification rate [DEA], maximal nitrification rate [NEA], and NH4+ affinity of the microbial community [NHScom]) were measured at two fertilization levels under controlled growth conditions. Plant traits were powerful predictors of plant–microbe interactions, but relevant plant traits differed in rela...
Soil Biology and Biochemistry, 2005
ABSTRACT We examined whether grass species and soil nitrogen (N) availability could enhance Carbo... more ABSTRACT We examined whether grass species and soil nitrogen (N) availability could enhance Carbon (C) and N turnover during root litter decay in grassland. Three species with increasing competitiveness (Festuca ovina, Dactylis glomerata and Lolium perenne) were grown at two N fertiliser levels in an undisturbed grassland soil, in which soil organic fractions derived for the last 9 years from Lolium root litter which was 13C-depleted. During the subsequent experimental year, the C turnover was calculated using the respective δ13C values of the old and new C in the root phytomass, in two Particulate Organic Matter (POM) fractions above 200μm and in the lightest part of the aggregated soil fraction between 50 and 200μm. Soil N availability was monitored during the regrowth periods with ion exchange resins (IER). The C decay rates of each particle size fraction were calculated with a simple mechanistic model of C dynamics. The N mineralisation immobilisation turnover (MIT) was characterised by dilution of 15N-labelled fertiliser in the N harvestThe C:N ratio and the residence time of C in the fractions decreased with particle size. The presence of a grass rhizosphere increased the decay rate of old C. Accumulation of new C in particle size fractions increased with species competitiveness and with N supply. Species competitiveness increased C turnover in the aggregated fraction, as a result of greater accumulation of new C and faster decay of old C. Fertiliser N increased N turnover and C mineralisation in the SOM. Species competitiveness decreased soil NO3−-N exchanged with the IER and increased dissolved organic C (DOC) content. The nature of the current rhizosphere is thus an important factor driving C and N transformations of the old root litter, in relation with grass species strategy. Plant competitiveness may stimulate the C and N turnover in the more evolved SOM fractions in a similar way to the mineral N supply.
Plant and Soil, 2004
Root litter transformation is an important determinant of the carbon cycle in grassland ecosystem... more Root litter transformation is an important determinant of the carbon cycle in grassland ecosystems. Litter quality and rhizosphere activity are species-dependent factors which depend on the attributes of the dead and living roots respectively. These factors were tested, using non-disturbed soil monoliths of Dactylis glomerata L. and Lolium perenne L. monocultures. 13 C-labelled root litter from these monoliths was obtained from a first stand of each crop, cultivated under very δ 13 C-depleted atmospheric CO 2 (S1). In a factorial design, 13 C-labelled root litter of each species was submitted to a second, non 13 C-labelled, living stand of each species (S2). Carbon derived from S1 and from S2 was measured during an 18-month incubation in the root phytomass and in three particulate organic matter fractions (POM). The decay rate of each particle size fraction was fitted to the experimental data in a mechanistic model of litter transformation, whose outputs were mineralisation and stabilisation of the litter-C. Few differences were found between species, in the amount and biochemical composition of the initial root litter, but Dactylis roots showed a greater C:N ratio, a lower mean root diameter and a greater specific root length compared to Lolium. A transient accumulation of litter residues arose successively in POM fractions of decreasing particle size. The litter-continuum hypothesis was validated, i.e. that the attributes of the compartments (C:N, chemical composition and residence time) depended mainly on their particle size. The S1 species influenced the rate of litter decay while the S2 species controlled the efficiency of litter-C stabilisation versus mineralisation: Dactylis litter decomposed faster and Lolium rhizosphere allowed a greater proportion of litter C stabilisation. Discussions focus on the processes responsible of species strategy in relation with the morphological root traits, and the implication of strategy diversity for rich grassland communities.
Plant and Soil, 2013
ABSTRACT Backgrounds and aims Plant nutrition strategies play a crucial role in community structu... more ABSTRACT Backgrounds and aims Plant nutrition strategies play a crucial role in community structure and ecosystem functioning. However, these strategies have been established only for nitrogen (N) acquisition, and it is not known whether similar strategies hold for other macronutrients such as sulphur (S). The aim of our study was to determine whether strategies for S acquisition of some grassland species were similar to those observed for N acquisition, and to analyse the relationships between these plant strategies and the soil microbial activity involved in soil organic S mineralisation. Methods We used three exploitative and three conservative grass species grown with and without S fertilisation. We measured a set of plant traits, namely root and shoot biomass, leaf area, root length, N and S content, leaf nutrient use efficiency, and sulphate uptake rates in plants, and one microbial trait linked to S mineralisation, namely soil arylsulphatase activity. Results The set of plant traits differentiated exploitative from conservative species. Close relationships were found between traits associated with strategies for N acquisition, namely total N content and Leaf N Use Efficiency (LNUE), and traits associated with strategies for S acquisition, namely total S content and Leaf S Use Efficiency (LSUE). Exploitative species exhibited similar or lower sulphate uptake capacities per unit of biomass than conservative species, but acquired more S through their larger root systems. Greater arylsulphatase activity was observed in the rhizosphere of the most exploitative species. Conclusion Overall, our results show that nutrient strategies defined in grassland species for N acquisition can be extended to S.
Journal of the Science of Food and Agriculture, 2011
BACKGROUND: Improving the hygienic quality of forages for horse nutrition seems to be a reasonabl... more BACKGROUND: Improving the hygienic quality of forages for horse nutrition seems to be a reasonable target for decreasing the prevalence of pulmonary diseases. The aim of the experiment was to study the effects of different agricultural practices on the main aero-allergens contained in forages, including breathable dust, fungi, mycotoxins and pollens. RESULTS: Results showed that the late harvest of hay, a second crop or a haylage production provides a good alternative to increase hygienic quality by reducing fungi contamination and breathable dust content. Barn drying of hay, while having no effect on breathable dust, similarly reduced fungi contamination. In contrast, when hay was harvested at a lower dry mass content (750 g DM kg -1 versus 850 g DM kg -1 ), both breathable dust and fungi contaminations were increased, which could at least be reversed by adding propionic acid just before baling. Zearalenone was detected in different hays, and even in one case, in breathable dust. CONCLUSION: Overall, our data suggest that different approaches can be used to increase forage hygienic quality for horse feeding and thus reduce their exposure to factors involved in equine pulmonary disease.
Journal of Experimental Botany, 2009
The role of S in legume growth, N uptake, and N 2 fixation was investigated using white clover (T... more The role of S in legume growth, N uptake, and N 2 fixation was investigated using white clover (Trifolium repens L.) as a model species. We examined whether the effect of sulphate addition on N fixation resulted from a stimulation of host plant growth, a specific effect of S on nodulation, or a specific effect of S on nodule metabolism. Clones of white clover, inoculated with Rhizobium leguminosarum, were grown for 140 d in a hydroponic system with three levels of sulphate concentration (0 mM, 0.095 mM, and 0.380 mM). Nodule morphological and biochemical traits, such as root length, nodule biomass and volume, nodule protein contents (nitrogenase and leghaemoglobin obtained by an immunological approach), and root amino acid concentrations, were used to analyse the effect of sulphate availability on N 2 fixation. The application of sulphate increased whole plant dry mass, root length, and nodule biomass, expressed on a root-length basis. N uptake proved less sensitive than N 2 fixation to the effects of S-deficiency, and decreased as a consequence of the lower root length observed in S-deficient plants. N 2 fixation was drastically reduced in S-deficient plants as a consequence of a low nodule development, but also due to low nitrogenase and leghaemoglobin production. This effect is likely to be due to down-regulation by a N-feedback mechanism, as, under severe S-deficiency, the high concentration of whole plant N and the accumulation of N-rich amino acids (such as asparagine) indicated that the assimilation of N exceeded the amount required for plant growth.
Journal of Experimental Botany, 2007
The aim of this study was to evaluate if a model describing the efflux and the influx of C throug... more The aim of this study was to evaluate if a model describing the efflux and the influx of C through the root surface could be fitted to experimental short-term kinetics of carbon (C) exudation by individual apical root segments in maize (Zea mays L.). The efflux of C was set constant or modelled by a power function of the distance from the apex to simulate the greater release of C around the root tip commonly reported in the literature. The influx was proportional to the C concentration in the external solution to simulate the active re-uptake of exudates by the root. Plants were exposed to full light or to shade to manipulate C allocation to roots. The model with a constant efflux gave satisfactory fits to the kinetics of exudation (average R 2 =0.66). The average gross efflux was then 2.1 mg C cm 22 root surface h 21 . The model was improved if exudation was set more intense towards the root apex (average R 2 =0.74). The estimated gross efflux decreased then from 5.2 mg C cm 22 h 21 at the apex to 1.8 mg C cm 22 h 21 for the region located 5-25 cm from the root tip. The decrease in net exudation of individual roots due to the shading of plants was weak, which may indicate that the import of C by the primary roots studied was not reduced significantly. By describing the exudation of an apical root segment of variable length and diameter, the model is a first step in linking exudation to root system architecture models and to whole plant functioning.
Grass and Forage Science, 2010
Pulmonary diseases such as recurrent airway obstruction have become a major concern in the horse ... more Pulmonary diseases such as recurrent airway obstruction have become a major concern in the horse industry. Airborne dust, including aeroallergens from forages, is suspected to be the main factor in its aetiology. Hypothesizing that grassland flora could affect hay hygienic quality, and therefore have implications for the respiratory health of horses, we compared five single-species hays (Trifolium repens, Lolium perenne, Alopecurus geniculatus, Poa trivialis and Holcus lanatus). Multi-species hay from Normandy, and different commercial forages (single-species haylage, multispecies haylage, Crau hay and hay from Swiss mixing), chosen to represent current horse forages, were also investigated. Dust, moulds, pollens and endotoxins were different among forage types, while mycotoxins were not detected in any of the forage types. Holcus lanatus hay was the dustiest among the single-species hays but also the least contaminated by moulds. A particular mould profile was associated with each plant species. The four commercial forages appeared to have a better hygienic quality than the multi-species hay. Among commercial forages, the single-species haylage was the least dusty but also the most contaminated by moulds. Overall the results suggest that the hygienic quality of equine forages could be improved by an appropriate choice of grassland species.
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Papers by Emmanuelle Personeni