Background: Fermentative aromas play a key role in the organoleptic profile of young wines. Their production depends both on yeast strain and fermentation conditions. A present-day trend in the wine industry consists in developing new strains with aromatic properties using adaptive evolution approaches. An evolved strain, Affinity T ECA5, overproducing esters, was recently obtained. In this study, dynamics of nitrogen consumption and of the fermentative aroma synthesis of the evolved and its ancestral strains were compared and coupled with a transcriptomic analysis approach to better understand the metabolic reshaping of Affinity T ECA5. Results: Nitrogen assimilation was different between the two strains, particularly amino acids transported by carriers regulated by nitrogen catabolite repression. We also observed differences in the kinetics of fermentative aroma production, especially in the bioconversion of higher alcohols into acetate esters. Finally, transcriptomic data showed that the enhanced bioconversion into acetate esters by the evolved strain was associated with the repression of genes involved in sterol biosynthesis rather than an enhanced expression of ATF1 and ATF2 (genes coding for the enzymes responsible for the synthesis of acetate esters from higher alcohols). Conclusions: An integrated approach to yeast metabolism-combining transcriptomic analyses and online monitoring data-showed differences between the two strains at different levels. Differences in nitrogen source consumption were observed suggesting modifications of NCR in the evolved strain. Moreover, the evolved strain showed a different way of managing the lipid source, which notably affected the production of acetate esters, likely because of a greater availability of acetyl-CoA for the evolved strain.

Background: Fermentative aromas play a key role in the organoleptic profile of young wines. Their production depends both on yeast strain and fermentation conditions. A present-day trend in the wine industry consists in developing new strains with aromatic properties using adaptive evolution approaches. An evolved strain, Affinity T ECA5, overproducing esters, was recently obtained. In this study, dynamics of nitrogen consumption and of the fermentative aroma synthesis of the evolved and its ancestral strains were compared and coupled with a transcriptomic analysis approach to better understand the metabolic reshaping of Affinity T ECA5. Results: Nitrogen assimilation was different between the two strains, particularly amino acids transported by carriers regulated by nitrogen catabolite repression. We also observed differences in the kinetics of fermentative aroma production, especially in the bioconversion of higher alcohols into acetate esters. Finally, transcriptomic data showed that the enhanced bioconversion into acetate esters by the evolved strain was associated with the repression of genes involved in sterol biosynthesis rather than an enhanced expression of ATF1 and ATF2 (genes coding for the enzymes responsible for the synthesis of acetate esters from higher alcohols). Conclusions: An integrated approach to yeast metabolism-combining transcriptomic analyses and online monitoring data-showed differences between the two strains at different levels. Differences in nitrogen source consumption were observed suggesting modifications of NCR in the evolved strain. Moreover, the evolved strain showed a different way of managing the lipid source, which notably affected the production of acetate esters, likely because of a greater availability of acetyl-CoA for the evolved strain.

By living in permanent burrows and incorporating organic detritus from the soil surface, anecic earthworms contribute to soil heterogeneity, but their impact is still under-studied in natural field conditions. We investigated the effects of the anecic earthworm Lumbricus centralis on fresh carbon (C) incorporation, soil organic matter composition, protists, and nematodes of a Cambisol under grassland. We used plant material labelled with stable isotope tracers to detect fresh C input around earthworm-occupied burrows or around burrows from which the earthworm had been removed. After 50 days, we sampled soil (0-10 cm depth) in concentric layers around the burrows, distinguishing between drilosphere (0-8 mm) and bulk soil (50-75 mm). L. centralis effectively incorporated fresh C into the drilosphere, and this shifted soil organic matter amount and chemistry: total soil sugar content was increased compared to unoccupied drilosphere and bulk soil, and the contribution of plant-derived sugars to soil organic matter was enhanced. Earthworms also shifted the spatial distribution of soil C towards the drilosphere. The total abundance of protists and nematodes was only slightly higher in earthworm-occupied drilosphere, but strong positive effects were found for some protist clades (e.g. Stenamoeba spp.). Additional data for the co-occurring anecic earthworm species Aporrectodea longa showed that it incorporated fresh C less than L. centralis, suggesting that the two species may have different effects on soil C distribution and organic matter quality.

By living in permanent burrows and incorporating organic detritus from the soil surface, anecic earthworms contribute to soil heterogeneity, but their impact is still under-studied in natural field conditions. We investigated the effects of the anecic earthworm Lumbricus centralis on fresh carbon (C) incorporation, soil organic matter composition, protists, and nematodes of a Cambisol under grassland. We used plant material labelled with stable isotope tracers to detect fresh C input around earthworm-occupied burrows or around burrows from which the earthworm had been removed. After 50 days, we sampled soil (0–10 cm depth) in concentric layers around the burrows, distinguishing between drilosphere (0–8 mm) and bulk soil (50–75 mm). L. centralis effectively incorporated fresh C into the drilosphere, and this shifted soil organic matter amount and chemistry: total soil sugar content was increased compared to unoccupied drilosphere and bulk soil, and the contribution of plant-derived sugars to soil organic matter was enhanced. Earthworms also shifted the spatial distribution of soil C towards the drilosphere. The total abundance of protists and nematodes was only slightly higher in earthworm-occupied drilosphere, but strong positive effects were found for some protist clades (e.g. Stenamoeba spp.). Additional data for the co-occurring anecic earthworm species Aporrectodea longa showed that it incorporated fresh C less than L. centralis, suggesting that the two species may have different effects on soil C distribution and organic matter quality.

By living in permanent burrows and incorporating organic detritus from the soil surface, anecic earthworms contribute to soil heterogeneity, but their impact is still under-studied in natural field conditions. We investigated the effects of the anecic earthworm Lumbricus centralis on fresh carbon (C) incorporation, soil organic matter composition, protists, and nematodes of a Cambisol under grassland. We used plant material labelled with stable isotope tracers to detect fresh C input around earthworm-occupied burrows or around burrows from which the earthworm had been removed. After 50 days, we sampled soil (0-10 cm depth) in concentric layers around the burrows, distinguishing between drilosphere (0-8 mm) and bulk soil (50-75 mm). L. centralis effectively incorporated fresh C into the drilosphere, and this shifted soil organic matter amount and chemistry: total soil sugar content was increased compared to unoccupied drilosphere and bulk soil, and the contribution of plant-derived sugars to soil organic matter was enhanced. Earthworms also shifted the spatial distribution of soil C towards the drilosphere. The total abundance of protists and nematodes was only slightly higher in earthworm-occupied drilosphere, but strong positive effects were found for some protist clades (e.g. Stenamoeba spp.). Additional data for the co-occurring anecic earthworm species Aporrectodea longa showed that it incorporated fresh C less than L. centralis, suggesting that the two species may have different effects on soil C distribution and organic matter quality.

By living in permanent burrows and incorporating organic detritus from the soil surface, anecic earthworms contribute to soil heterogeneity, but their impact is still under-studied in natural field conditions. We investigated the effects of the anecic earthworm Lumbricus centralis on fresh carbon (C) incorporation, soil organic matter composition, protists, and nematodes of a Cambisol under grassland. We used plant material labelled with stable isotope tracers to detect fresh C input around earthworm-occupied burrows or around burrows from which the earthworm had been removed. After 50 days, we sampled soil (0-10 cm depth) in concentric layers around the burrows, distinguishing between drilosphere (0-8 mm) and bulk soil (50-75 mm). L. centralis effectively incorporated fresh C into the drilosphere, and this shifted soil organic matter amount and chemistry: total soil sugar content was increased compared to unoccupied drilosphere and bulk soil, and the contribution of plant-derived sugars to soil organic matter was enhanced. Earthworms also shifted the spatial distribution of soil C towards the drilosphere. The total abundance of protists and nematodes was only slightly higher in earthworm-occupied drilosphere, but strong positive effects were found for some protist clades (e.g. Stenamoeba spp.). Additional data for the co-occurring anecic earthworm species Aporrectodea longa showed that it incorporated fresh C less than L. centralis, suggesting that the two species may have different effects on soil C distribution and organic matter quality.

Direct comparison of cow and goat performance and milk fatty acid responses to diets known to induce milk fat depression (MFD) in the bovine reveals relevant species-by-diet interactions in ruminal lipid metabolism. Thus, this study was conducted to infer potential mechanisms responsible for differences in the rumen microbial biohydrogenation (BH) due to diet and ruminant species. To meet this objective, 12 cows and 15 goats were fed a basal diet (control), a similar diet supplemented with 2.2% fish oil (FO), or a diet containing 5.3% sunflower oil and additional starch (+38%; SOS) according to a 3 × 3 Latin square design with 25-d experimental periods. On the last day of each period, fatty acid composition (by gas chromatography) and bacterial community (by terminal-RFLP), as well as fermentation characteristics, were measured in rumen fluid samples. Results showed significant differences in the response of cows and goats to dietary treatments, although variations in some fermentation parameters (e.g., decreases in the acetate-to-propionate ratio due to FO or SOS) were similar in both species. Main alterations in ruminal BH pathways potentially responsible for MFD on the SOS diet (i.e., the shift from trans-11 to trans-10 18:1 and related increases in trans-10,cis-12 18:2) tended to be more pronounced in cows, which is consistent with an associated MFD only in this species. However, changes linked to FO-induced MFD (e.g., decreases in 18:0 and increases in total trans-18:1) were stronger in caprine rumen fluid, which may explain their unexpected susceptibility (although less marked than in bovine) to the negative effect of FO on milk fat content. Altogether, these results suggest that distinct ruminal mechanisms lead to each type of diet-induced MFD and confirm a pronounced interaction with species. With regard to microbiota, differences between cows and goats in the composition of the rumen bacterial community might be behind the disparity in the microorganisms affected by the experimental diets (e.g., Ruminococcaceae, Lachnospiraceae, and Succinivibrionaceae in the bovine, and Pseudobutryrivibrio, Clostridium cluster IV, Prevotella, and Veillonellaceae in the caprine), which hindered the assignation of bacterial populations to particular BH steps or pathways. Furthermore, most relevant variations in microbial groups corresponded to as yet uncultured bacteria and suggest that these microorganisms may play a predominant role in the ruminal lipid metabolism in both cows and goats.

Direct comparison of cow and goat performance and milk fatty acid responses to diets known to induce milk fat depression (MFD) in the bovine reveals relevant species-by-diet interactions in ruminal lipid metabolism. Thus, this study was conducted to infer potential mechanisms responsible for differences in the rumen microbial biohydrogenation (BH) due to diet and ruminant species. To meet this objective, 12 cows and 15 goats were fed a basal diet (control), a similar diet supplemented with 2.2% fish oil (FO), or a diet containing 5.3% sunflower oil and additional starch (+38%; SOS) according to a 3×3 Latin square design with 25-d experimental periods. On the last day of each period, fatty acid composition (by gas chromatography) and bacterial community (by terminal-RFLP), as well as fermentation characteristics, were measured in rumen fluid samples. Results showed significant differences in the response of cows and goats to dietary treatments, although variations in some fermentation parameters (e.g., decreases in the acetate-to-propionate ratio due to FO or SOS) were similar in both species. Main alterations in ruminal BH pathways potentially responsible for MFD on the SOS diet (i.e., the shift from trans-11 to trans-10 18:1 and related increases in trans-10,cis-12 18:2) tended to be more pronounced in cows, which is consistent with an associated MFD only in this species. However, changes linked to FO-induced MFD (e.g., decreases in 18:0 and increases in total trans-18:1) were stronger in caprine rumen fluid, which may explain their unexpected susceptibility (although less marked than in bovine) to the negative effect of FO on milk fat content. Altogether, these results suggest that distinct ruminal mechanisms lead to each type of diet-induced MFD and confirm a pronounced interaction with species. With regard to microbiota, differences between cows and goats in the composition of the rumen bacterial community might be behind the disparity in the microorganisms affected by the experimental diets (e.g., Ruminococcaceae, Lachnospiraceae, and Succinivibrionaceae in the bovine, and Pseudobutryrivibrio, Clostridium cluster IV, Prevotella, and Veillonellaceae in the caprine), which hindered the assignation of bacterial populations to particular BH steps or pathways. Furthermore, most relevant variations in microbial groups corresponded to as yet uncultured bacteria and suggest that these microorganisms may play a predominant role in the ruminal lipid metabolism in both cows and goats.

Direct comparison of cow and goat performance and milk fatty acid responses to diets known to induce milk fat depression (MFD) in the bovine reveals relevant species-by-diet interactions in ruminal lipid metabolism. Thus, this study was conducted to infer potential mechanisms responsible for differences in the rumen microbial biohydrogenation (BH) due to diet and ruminant species. To meet this objective, 12 cows and 15 goats were fed a basal diet (control), a similar diet supplemented with 2.2% fish oil (FO), or a diet containing 5.3% sunflower oil and additional starch (+38%; SOS) according to a 3 × 3 Latin square design with 25-d experimental periods. On the last day of each period, fatty acid composition (by gas chromatography) and bacterial community (by terminal-RFLP), as well as fermentation characteristics, were measured in rumen fluid samples. Results showed significant differences in the response of cows and goats to dietary treatments, although variations in some fermentation parameters (e.g., decreases in the acetate-to-propionate ratio due to FO or SOS) were similar in both species. Main alterations in ruminal BH pathways potentially responsible for MFD on the SOS diet (i.e., the shift from trans-11 to trans-10 18:1 and related increases in trans-10,cis-12 18:2) tended to be more pronounced in cows, which is consistent with an associated MFD only in this species. However, changes linked to FO-induced MFD (e.g., decreases in 18:0 and increases in total trans-18:1) were stronger in caprine rumen fluid, which may explain their unexpected susceptibility (although less marked than in bovine) to the negative effect of FO on milk fat content. Altogether, these results suggest that distinct ruminal mechanisms lead to each type of diet-induced MFD and confirm a pronounced interaction with species. With regard to microbiota, differences between cows and goats in the composition of the rumen bacterial community might be behind the disparity in the microorganisms affected by the experimental diets (e.g., Ruminococcaceae, Lachnospiraceae, and Succinivibrionaceae in the bovine, and Pseudobutryrivibrio, Clostridium cluster IV, Prevotella, and Veillonellaceae in the caprine), which hindered the assignation of bacterial populations to particular BH steps or pathways. Furthermore, most relevant variations in microbial groups corresponded to as yet uncultured bacteria and suggest that these microorganisms may play a predominant role in the ruminal lipid metabolism in both cows and goats.

The three cool-season perennial forage grasses cocksfoot/orchardgrass, Dactylis glomerata L., tall fescue, Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh., and phalaris/harding grass, Phalaris aquatica L., are of major economic and ecological importance in regions with summer-dry environments. This review considers the constraints that these species are likely to experience under current and predicted increase of droughts due to climate change scenarios in south-eastern Australia, the southern Great Plains of USA and the Western Mediterranean Basin. The review identifies research required to maximise the development and use of C3 cool-season grasses with enhanced resilience to drought while considering the concern of some regulators that these grasses may be potential weeds. The state of knowledge of factors influencing plant drought survival and therefore recovery after stress and long-term persistence is discussed in the light of adaptive strategies. The major research needs identified to enhance traits conferring drought survival include (1) increasing the depth and density of grass root systems to strengthen dehydration avoidance; (2) exploring the biochemical, molecular and hydraulic bases of dehydration tolerance and improving techniques to measure this trait; (3) breaking the trade-off between summer dormancy and forage yield potential and improving understanding of environmental, biochemical and genetic controls over summer dormancy; (4) identifying non-toxic endophyte strains compatible with summer-dormant cultivars of tall fescue to enhance drought survival; and (5) enhancing seed production capability of new cultivars as well as the development of agronomic management packages for promoting stable mixtures combining perennial grasses and legumes. The weed potential of newly introduced summer-dormant cultivars is concluded to be minor. The research directions proposed here should improve pasture grass resilience and forage crop sustainability in Mediterranean and temperate summer-dry environments under the future drier and warmer conditions associated with climate change.

The three cool-season perennial forage grasses cocksfoot/orchardgrass, Dactylis glomerata L., tall fescue, Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh., and phalaris/harding grass, Phalaris aquatica L., are of major economic and ecological importance in regions with summer-dry environments. This review considers the constraints that these species are likely to experience under current and predicted increase of droughts due to climate change scenarios in south-eastern Australia, the southern Great Plains of USA and the Western Mediterranean Basin. The review identifies research required to maximise the development and use of C3 cool-season grasses with enhanced resilience to drought while considering the concern of some regulators that these grasses may be potential weeds. The state of knowledge of factors influencing plant drought survival and therefore recovery after stress and long-term persistence is discussed in the light of adaptive strategies. The major research needs identified to enhance traits conferring drought survival include (1) increasing the depth and density of grass root systems to strengthen dehydration avoidance; (2) exploring the biochemical, molecular and hydraulic bases of dehydration tolerance and improving techniques to measure this trait; (3) breaking the trade-off between summer dormancy and forage yield potential and improving understanding of environmental, biochemical and genetic controls over summer dormancy; (4) identifying non-toxic endophyte strains compatible with summer-dormant cultivars of tall fescue to enhance drought survival; and (5) enhancing seed production capability of new cultivars as well as the development of agronomic management packages for promoting stable mixtures combining perennial grasses and legumes. The weed potential of newly introduced summer-dormant cultivars is concluded to be minor. The research directions proposed here should improve pasture grass resilience and forage crop sustainability in Mediterranean and temperate summer-dry environments under the future drier and warmer conditions associated with climate change.

The three cool-season perennial forage grasses cocksfoot/orchardgrass, Dactylis glomerata L., tall fescue, Festuca arundinacea Schreb. syn. Lolium arundinaceum (Schreb.) Darbysh., and phalaris/harding grass, Phalaris aquatica L., are of major economic and ecological importance in regions with summer-dry environments. This review considers the constraints that these species are likely to experience under current and predicted increase of droughts due to climate change scenarios in south-eastern Australia, the southern Great Plains of USA and the Western Mediterranean Basin. The review identifies research required to maximise the development and use of C3 cool-season grasses with enhanced resilience to drought while considering the concern of some regulators that these grasses may be potential weeds. The state of knowledge of factors influencing plant drought survival and therefore recovery after stress and long-term persistence is discussed in the light of adaptive strategies. The major research needs identified to enhance traits conferring drought survival include (1) increasing the depth and density of grass root systems to strengthen dehydration avoidance; (2) exploring the biochemical, molecular and hydraulic bases of dehydration tolerance and improving techniques to measure this trait; (3) breaking the trade-off between summer dormancy and forage yield potential and improving understanding of environmental, biochemical and genetic controls over summer dormancy; (4) identifying non-toxic endophyte strains compatible with summer-dormant cultivars of tall fescue to enhance drought survival; and (5) enhancing seed production capability of new cultivars as well as the development of agronomic management packages for promoting stable mixtures combining perennial grasses and legumes. The weed potential of newly introduced summer-dormant cultivars is concluded to be minor. The research directions proposed here should improve pasture grass resilience and forage crop sustainability in Mediterranean and temperate summer-dry environments under the future drier and warmer conditions associated with climate change.

Plants are constantly exposed to a variety of biotic and abiotic stresses that reduce their fitness and performance. At the molecular level, the perception of extracellular stimuli and the subsequent activation of defense responses require a complex interplay of signaling cascades, in which protein phosphorylation plays a central role. Several studies have shown that some members of the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) family are involved in stress and developmental pathways. We report here a systematic analysis of the role of the members of this gene family by mutant phenotyping in the monocotyledon model plant rice, Oryza sativa. We have then targeted 176 of the ∼320 LRR-RLK genes (55.7%) and genotyped 288 mutant lines. Position of the insertion was confirmed in 128 lines corresponding to 100 LRR-RLK genes (31.6% of the entire family). All mutant lines harboring homozygous insertions have been screened for phenotypes under normal conditions and under various abiotic stresses. Mutant plants have been observed at several stages of growth, from seedlings in Petri dishes to flowering and grain filling under greenhouse conditions. Our results show that 37 of the LRR-RLK rice genes are potential targets for improvement especially in the generation of abiotic stress tolerant cereals.

Plants are constantly exposed to a variety of biotic and abiotic stresses that reduce their fitness and performance. At the molecular level, the perception of extracellular stimuli and the subsequent activation of defense responses require a complex interplay of signaling cascades, in which protein phosphorylation plays a central role. Several studies have shown that some members of the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) family are involved in stress and developmental pathways. We report here a systematic analysis of the role of the members of this gene family by mutant phenotyping in the monocotyledon model plant rice, Oryza sativa. We have then targeted 176 of the ?320 LRR-RLK genes (55.7%) and genotyped 288 mutant lines. Position of the insertion was confirmed in 128 lines corresponding to 100 LRR-RLK genes (31.6% of the entire family). All mutant lines harboring homozygous insertions have been screened for phenotypes under normal conditions and under various abiotic stresses. Mutant plants have been observed at several stages of growth, from seedlings in Petri dishes to flowering and grain filling under greenhouse conditions. Our results show that 37 of the LRR-RLK rice genes are potential targets for improvement especially in the generation of abiotic stress tolerant cereals. (Résumé d'auteur)

BGPI : équipe 4 | International audience | Plants are constantly exposed to a variety of biotic and abiotic stresses that reduce their fitness and performance. At the molecular level, the perception of extracellular stimuli and the subsequent activation of defense responses require a complex interplay of signaling cascades, in which protein phosphorylation plays a central role. Several studies have shown that some members of the Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) family are involved in stress and developmental pathways. We report here a systematic analysis of the role of the members of this gene family by mutant phenotyping in the monocotyledon model plant rice, Oryza sativa. We have then targeted 176 of the ∼320 LRR-RLK genes (55.7%) and genotyped 288 mutant lines. Position of the insertion was confirmed in 128 lines corresponding to 100 LRR-RLK genes (31.6% of the entire family). All mutant lines harboring homozygous insertions have been screened for phenotypes under normal conditions and under various abiotic stresses. Mutant plants have been observed at several stages of growth, from seedlings in Petri dishes to flowering and grain filling under greenhouse conditions. Our results show that 37 of the LRR-RLK rice genes are potential targets for improvement especially in the generation of abiotic stress tolerant cereals.

Targeted sequence capture is a promising technology which helps reduce costs for sequencing and genotyping numerous genomic regions in large sets of individuals. Bait sequences are designed to capture specific alleles previously discovered in parents or reference populations. We studied a set of 135 RILs originating from a cross between an emmer cultivar (Dic2) and a recent durum elite cultivar (Silur). Six thousand sequence baits were designed to target Dic2 vs. Silur polymorphisms discovered in a previous RNAseq study. These baits were exposed to genomic DNA of the RIL population. Eighty percent of the targeted SNPs were recovered, 65% of which were of high quality and coverage. The final high density genetic map consisted of more than 3,000 markers, whose genetic and physical mapping were consistent with those obtained with large arrays.

Targeted sequence capture is a promising technology which helps reduce costs for sequencing and genotyping numerous genomic regions in large sets of individuals. Bait sequences are designed to capture specific alleles previously discovered in parents or reference populations. We studied a set of 135 RILs originating from a cross between an emmer cultivar (Dic2) and a recent durum elite cultivar (Silur). Six thousand sequence baits were designed to target Dic2 vs. Silur polymorphisms discovered in a previous RNAseq study. These baits were exposed to genomic DNA of the RIL population. Eighty percent of the targeted SNPs were recovered, 65% of which were of high quality and coverage. The final high density genetic map consisted of more than 3,000 markers, whose genetic and physical mapping were consistent with those obtained with large arrays.

Mycotoxins and trace elements are contaminants whose content in harvested organs is regulated forfeed and food. The tightening of European regulations requires to better understand the state anddeterminism of these contaminations. The proposed approach of multicontaminants raised descriptiveand explicative data contamination in field conditions and their cross effects. In order to have a range ofsoil and climatic situations, the work was based on a permanent national network of plots. The firsthypotheses of relationships between environmental factors, the technical process and contaminationswere proposed. To ensure reproducibility and traceability of samples and measurements, a samplingguide for wheat and sunflower grains has been defined and validated for the determination of traceelement concentrations in wheat grain and sunflower. | Les mycotoxines et les éléments traces sont des contaminants dont la teneur dans les organes récoltés est réglementée pour l’alimentation animale et humaine. Le durcissement des règlementations européennes entraîne la nécessité de mieux connaître l’état et le déterminisme de ces contaminations. L’approche multicontaminants proposée a permis de recueillir des données descriptives et explicatives des contaminations en conditions de plein champ et de leurs effets croisés. Afin de disposer d’une diversité de situations pédologiques et climatiques, les travaux se sont appuyés sur un réseau pérenne de parcelles mis en place à l’échelle du territoire national. Des premières hypothèses relatives aux relations entre les facteurs du milieu, l’itinéraire technique et l’apparition des contaminations ont été émises. Pour garantir la reproductibilité du prélèvement et la traçabilité des échantillons et mesures, un guide d’échantillonnage de grains de blé et de tournesol a été défini et validé pour la détermination de la concentration en éléments traces dans les grains de blé tendre et de tournesol.

Mycotoxins and trace elements are contaminants whose content in harvested organs is regulated forfeed and food. The tightening of European regulations requires to better understand the state anddeterminism of these contaminations. The proposed approach of multicontaminants raised descriptiveand explicative data contamination in field conditions and their cross effects. In order to have a range ofsoil and climatic situations, the work was based on a permanent national network of plots. The firsthypotheses of relationships between environmental factors, the technical process and contaminationswere proposed. To ensure reproducibility and traceability of samples and measurements, a samplingguide for wheat and sunflower grains has been defined and validated for the determination of traceelement concentrations in wheat grain and sunflower. | Les mycotoxines et les éléments traces sont des contaminants dont la teneur dans les organes récoltés est réglementée pour l’alimentation animale et humaine. Le durcissement des règlementations européennes entraîne la nécessité de mieux connaître l’état et le déterminisme de ces contaminations. L’approche multicontaminants proposée a permis de recueillir des données descriptives et explicatives des contaminations en conditions de plein champ et de leurs effets croisés. Afin de disposer d’une diversité de situations pédologiques et climatiques, les travaux se sont appuyés sur un réseau pérenne de parcelles mis en place à l’échelle du territoire national. Des premières hypothèses relatives aux relations entre les facteurs du milieu, l’itinéraire technique et l’apparition des contaminations ont été émises. Pour garantir la reproductibilité du prélèvement et la traçabilité des échantillons et mesures, un guide d’échantillonnage de grains de blé et de tournesol a été défini et validé pour la détermination de la concentration en éléments traces dans les grains de blé tendre et de tournesol.

Ce 49ème volume de la Revue Innovations Agronomiques regroupe l'ensemble de la restitution des projets Casdar, présentés le 3 novembre 2015. | Mycotoxins and trace elements are contaminants whose content in harvested organs is regulated for feed and food. The tightening of European regulations requires to better understand the state and determinism of these contaminations. The proposed approach of multicontaminants raised descriptive and explicative data contamination in field conditions and their cross effects. In order to have a range of soil and climatic situations, the work was based on a permanent national network of plots. The first hypotheses of relationships between environmental factors, the technical process and contaminations were proposed. To ensure reproducibility and traceability of samples and measurements, a sampling guide for wheat and sunflower grains has been defined and validated for the determination of trace element concentrations in wheat grain and sunflower. | Les mycotoxines et les éléments traces sont des contaminants dont la teneur dans les organes récoltés est réglementée pour l’alimentation animale et humaine. Le durcissement des règlementations européennes entraîne la nécessité de mieux connaître l’état et le déterminisme de ces contaminations. L’approche multicontaminants proposée a permis de recueillir des données descriptives et explicatives des contaminations en conditions de plein champ et de leurs effets croisés. Afin de disposer d’une diversité de situations pédologiques et climatiques, les travaux se sont appuyés sur un réseau pérenne de parcelles mis en place à l’échelle du territoire national. Des premières hypothèses relatives aux relations entre les facteurs du milieu, l’itinéraire technique et l’apparition des contaminations ont été émises. Pour garantir la reproductibilité du prélèvement et la traçabilité des échantillons et mesures, un guide d’échantillonnage de grains de blé et de tournesol a été défini et validé pour la détermination de la concentration en éléments traces dans les grains de blé tendre et de tournesol.

Psyllids are vectors of phytoplasma, which cause important diseases of pome fruit trees. Psyllid species reported as phytoplasma vectors were captured during 2010–2011 in several pome fruit growing regions in Turkey. Potential psyllid vectors of ‘Candidatus Phytoplasma mali’ were collected from Malus spp. (apple), Cydonia oblonga (quince), Crataegus spp. (hawthorn) and also from the overwintering hosts, whereas those of ‘Candidatus Phytoplasma pyri’ were collected from wild and cultured forms of Pyrus spp. (pear) trees. The psyllids were identified morphologically as Cacopsylla picta, C. melanoneura-C. affinis complex, C. crataegi, C. pyrisuga, C. pyri, C. pyricola and other Cacopsylla species. The highest natural phytoplasma infection rate was found in C. picta followed by C. pyri, C. melanoneura-C. affinis complex and C. crataegi with rates of 4.36, 3.84, 2.77 and 1.67%, respectively. No phytoplasma were detected in C. pyrisuga, C. pyricola, or the other Cacopsylla spp. ‘Ca. P. mali’ was detected in C. picta, C. melanoneura-C. affinis complex and C. pyri; ‘Ca. P. pyri’ was detected in C. picta, C. crataegi, C. melanoneura-C. affinis complex and C. pyri individuals. To our knowledge, this is the first report on the possible psyllid vectors of ‘Ca. P. mali’ in Turkey.

BGPI : équipe 6 | Psyllids are vectors of phytoplasma, which cause important diseases of pome fruit trees. Psyllid species reported as phytoplasma vectors were captured during 2010–2011 in several pome fruit growing regions in Turkey. Potential psyllid vectors of ‘Candidatus Phytoplasma mali’ were collected from Malus spp. (apple), Cydonia oblonga (quince), Crataegus spp. (hawthorn) and also from the overwintering hosts, whereas those of ‘Candidatus Phytoplasma pyri’ were collected from wild and cultured forms of Pyrus spp. (pear) trees. The psyllids were identified morphologically as Cacopsylla picta, C. melanoneura-C. affinis complex, C. crataegi, C. pyrisuga, C. pyri, C. pyricola and other Cacopsylla species. The highest natural phytoplasma infection rate was found in C. picta followed by C. pyri, C. melanoneura-C. affinis complex and C. crataegi with rates of 4.36, 3.84, 2.77 and 1.67%, respectively. No phytoplasma were detected in C. pyrisuga, C. pyricola, or the other Cacopsylla spp. ‘Ca. P. mali’ was detected in C. picta, C. melanoneura-C. affinis complex and C. pyri; ‘Ca. P. pyri’ was detected in C. picta, C. crataegi, C. melanoneura-C. affinis complex and C. pyri individuals. To our knowledge, this is the first report on the possible psyllid vectors of ‘Ca. P. mali’ in Turkey.

Le groupe des Pseudomonas syringae est très divers, au niveau phénotypique, génétique et de ses habitats. Récemment, 13 phylogroupes et 23 clades qui prennent en compte la diversité génétique et celle des habitats de cette bactérie ubiquiste ont été décrits (Berge et al., 2014). Des outils moléculaires permettant d’identifier les P. syringae et leur phylogroupes ont été développés au laboratoire (Borschinger et al., soumis), et nous permettent de travailler sur de relativement grands effectifs d’isolats bactériens. Avec ces outils, en réalisant nous-même des prélèvements dans des vergers ciblés en 2014 et 2015, et en collaboration avec le CTIFL qui a réalisé deux importantes prospections en 2011-2012, nous avons exploré la diversité des P. syringae rencontrés dans 36 vergers d’abricotiers de la vallée du Rhône, où le chancre bactérien était présent, et ce dans différents compartiments : le sol, le couvre-sol, les débris de culture, la plante (greffon) à différents stades de son développement, les racines (porte-greffe), la plante avec ou sans symptômes déclarées. Les résultats obtenus montrent que, parmi les 2436 isolats collectés, les isolats potentiellement pathogènes proviennent de 4 phylogroupes différents qui montrent une grande diversité; par ailleurs, certains phylogroupes sont ubiquistes et d’autres spécialisés. Le sol, le couvre-sol, les débris de culture, la plante (avec ou sans symptômes visibles) sont des réservoirs potentiels de la maladie. Les conséquences en termes d’étiologie et détection du chancre bactérien de l’abricotier sont discutées.

Le groupe des Pseudomonas syringae est très divers, au niveau phénotypique, génétique et de ses habitats. Récemment, 13 phylogroupes et 23 clades qui prennent en compte la diversité génétique et celle des habitats de cette bactérie ubiquiste ont été décrits (Berge et al., 2014). Des outils moléculaires permettant d’identifier les P. syringae et leur phylogroupes ont été développés au laboratoire (Borschinger et al., soumis), et nous permettent de travailler sur de relativement grands effectifs d’isolats bactériens. Avec ces outils, en réalisant nous-même des prélèvements dans des vergers ciblés en 2014 et 2015, et en collaboration avec le CTIFL qui a réalisé deux importantes prospections en 2011-2012, nous avons exploré la diversité des P. syringae rencontrés dans 36 vergers d’abricotiers de la vallée du Rhône, où le chancre bactérien était présent, et ce dans différents compartiments : le sol, le couvre-sol, les débris de culture, la plante (greffon) à différents stades de son développement, les racines (porte-greffe), la plante avec ou sans symptômes déclarées. Les résultats obtenus montrent que, parmi les 2436 isolats collectés, les isolats potentiellement pathogènes proviennent de 4 phylogroupes différents qui montrent une grande diversité; par ailleurs, certains phylogroupes sont ubiquistes et d’autres spécialisés. Le sol, le couvre-sol, les débris de culture, la plante (avec ou sans symptômes visibles) sont des réservoirs potentiels de la maladie. Les conséquences en termes d’étiologie et détection du chancre bactérien de l’abricotier sont discutées.