16 research outputs found
Découverte d'une grotte et d'un squelette magdalénien au Cheix, prÚs Besse-en-Chandesse (Puy-de-DÎme)
Desrut Georges. Découverte d'une grotte et d'un squelette magdalénien au Cheix, prÚs Besse-en-Chandesse (Puy-de-DÎme). In: Bulletin de la Société préhistorique de France, tome 36, n°2, 1939. pp. 132-142
Mécanismes moléculaires impliqués dans les interactions entre Arabidopsis thaliana et des rhizobactéries bénéfiques : Implication du transport de sucres ?
Plants live in close relationships with complex populations of microorganisms, including rhizobacteria species commonly referred to as Plant Growth Promoting Rhizobacteria (PGPR). PGPR able to confer to plants an improved productivity but the molecular mechanisms involved in this process remain largely unknown. Using an in vitro experimental system, the model plant Arabidopsis thaliana, and the well characterized PGPR strain Pseudomonas simiae WCS417r, we have carried out a comprehensive set of phenotypic, gene expression, and biochemical analyses. Our results show PsWCS417r induces major transcriptional changes in sugar transport and in other key biological processes linked to plant growth, development and defense. Using a reverse genetic approach, we also demonstrate that AtSWEET11 and AtSWEET12, two sugar transporter genes whose expression is down-regulated by the PGPR, are functionally involved in its plant-growth promoting effects. Altogether, our findings reveal regulation of plant sugar transport plays a crucial role in determining the fate of plant-rhizobacteria interactions. We extended our study to two other PGPR and a non PGPR strain. Overall, our results show that all three bacterial strains tested are able to alter the expression of several plant sugar transporter genes (essentially genes of the AtSWEET and AtERD6-like families), either in roots or in shoot, and either in physical contact with the seedling roots or via the production of volatile compounds only. Altogether, our findings reveal conserved and strain-specific trancriptional regulation of sugar transport during plant-PGPR interactions. Lastly, we report the identification and characterization of a Bacillus megaterium endophytic strain, RmBm31, isolated from root nodules of the legume species Retama monosperma. Our study reveals RmBm31 is an IAA-producing endophytic bacterium that possess a large set of genes associated with plant growth promoting traits. Using the model plant species Arabidopsis, we demonstrate this strain display beneficial effects on plant growth and root development via the production of volatile compounds. These effects seem to involve auxin-independent signaling mechanisms.Les plantes vivent en Ă©troite relation avec des populations complexes de microorganismes, y compris des espĂšces de rhizobactĂ©ries communĂ©ment appelĂ©es rhizobactĂ©ries promotrices de la croissance des plantes (PGPR). Les PGPR confĂ©rĂšrent aux plantes une meilleure croissance et tolĂ©rance aux stress biotiques et abiotiques mais les mĂ©canismes molĂ©culaires impliquĂ©s dans ce processus restent largement inconnus. En utilisant un systĂšme expĂ©rimental in vitro, la plante modĂšle Arabidopsis thaliana et la souche PGPR bien caractĂ©risĂ©e Pseudomonas simiae WCS417r, nous avons rĂ©alisĂ© un ensemble complet d'analyses phĂ©notypiques, dâexpressions gĂ©niques et biochimiques. Nos rĂ©sultats montrent que PsWCS417r induit des modifications transcriptionnelles majeures du transport du sucre et d'autres processus biologiques clĂ©s liĂ©s Ă la croissance, au dĂ©veloppement et Ă la dĂ©fense des plantes. En utilisant une approche de gĂ©nĂ©tique inverse, nous avons Ă©galement dĂ©montrĂ© que AtSWEET11 et AtSWEET12, deux gĂšnes transporteurs de sucre dont l'expression est rĂ©primĂ©e par les souches bactĂ©riennes Ă©tudiĂ©es chez Arabidopsis thaliana, sont fonctionnellement impliquĂ©s dans les effets favorisant la croissance et le dĂ©veloppement des plantules. Nos rĂ©sultats rĂ©vĂšlent que la rĂ©gulation du transport de sucres joue un rĂŽle important dans les effets bĂ©nĂ©fiques des interactions plantes-rhizobactĂ©ries. Nous avons Ă©tendu notre Ă©tude Ă deux autres souches de PGPR (Pseudomonas fluorescens PICF7, Burkholderia phytofirmans PsJN) et Ă une autre souche non-PGPR (Escherichia coli DH5α). Ces trois souches bactĂ©riennes sont capables de modifier elles aussi lâexpression de plusieurs gĂšnes codant des transporteurs de sucre (essentiellement des gĂšnes des familles AtSWEET et AtERD6-like), soit dans les racines, soit dans les parties aĂ©riennes des plantules dâArabidopsis. Globalement, nos rĂ©sultats rĂ©vĂšlent une rĂ©gulation transcriptionnelle conservĂ©e ou spĂ©cifique de certains gĂšnes codants pour des transporteurs de sucres lors des interactions plante-PGPR. Enfin, nous avons effectuĂ© l'identification et la caractĂ©risation d'une souche Bacillus megaterium, RmBm31, isolĂ©e de nodules racinaires de la lĂ©gumineuse Retama monosperma. Notre Ă©tude rĂ©vĂšle que RmBm31 est une bactĂ©rie endophyte produisant de l'IAA et possĂ©dant un grand nombre de gĂšnes associĂ©s Ă des caractĂšres favorisant la croissance des plantes. En utilisant la plante modĂšle Arabidopsis, nous avons dĂ©montrĂ© que cette souche prĂ©sente des effets bĂ©nĂ©fiques sur la croissance et le dĂ©veloppement des plantules via la production de composĂ©s volatils. Ces effets semblent impliquer des mĂ©canismes de signalisation indĂ©pendants de l'auxine
Molecular Mechanisms involved in the interactions between Arabidopsis thaliana and plant growth promoting rhizobacteria : Implication of sugar transport ?
Les plantes vivent en Ă©troite relation avec des populations complexes de microorganismes, y compris des espĂšces de rhizobactĂ©ries communĂ©ment appelĂ©es rhizobactĂ©ries promotrices de la croissance des plantes (PGPR). Les PGPR confĂ©rĂšrent aux plantes une meilleure croissance et tolĂ©rance aux stress biotiques et abiotiques mais les mĂ©canismes molĂ©culaires impliquĂ©s dans ce processus restent largement inconnus. En utilisant un systĂšme expĂ©rimental in vitro, la plante modĂšle Arabidopsis thaliana et la souche PGPR bien caractĂ©risĂ©e Pseudomonas simiae WCS417r, nous avons rĂ©alisĂ© un ensemble complet d'analyses phĂ©notypiques, dâexpressions gĂ©niques et biochimiques. Nos rĂ©sultats montrent que PsWCS417r induit des modifications transcriptionnelles majeures du transport du sucre et d'autres processus biologiques clĂ©s liĂ©s Ă la croissance, au dĂ©veloppement et Ă la dĂ©fense des plantes. En utilisant une approche de gĂ©nĂ©tique inverse, nous avons Ă©galement dĂ©montrĂ© que AtSWEET11 et AtSWEET12, deux gĂšnes transporteurs de sucre dont l'expression est rĂ©primĂ©e par les souches bactĂ©riennes Ă©tudiĂ©es chez Arabidopsis thaliana, sont fonctionnellement impliquĂ©s dans les effets favorisant la croissance et le dĂ©veloppement des plantules. Nos rĂ©sultats rĂ©vĂšlent que la rĂ©gulation du transport de sucres joue un rĂŽle important dans les effets bĂ©nĂ©fiques des interactions plantes-rhizobactĂ©ries. Nous avons Ă©tendu notre Ă©tude Ă deux autres souches de PGPR (Pseudomonas fluorescens PICF7, Burkholderia phytofirmans PsJN) et Ă une autre souche non-PGPR (Escherichia coli DH5α). Ces trois souches bactĂ©riennes sont capables de modifier elles aussi lâexpression de plusieurs gĂšnes codant des transporteurs de sucre (essentiellement des gĂšnes des familles AtSWEET et AtERD6-like), soit dans les racines, soit dans les parties aĂ©riennes des plantules dâArabidopsis. Globalement, nos rĂ©sultats rĂ©vĂšlent une rĂ©gulation transcriptionnelle conservĂ©e ou spĂ©cifique de certains gĂšnes codants pour des transporteurs de sucres lors des interactions plante-PGPR. Enfin, nous avons effectuĂ© l'identification et la caractĂ©risation d'une souche Bacillus megaterium, RmBm31, isolĂ©e de nodules racinaires de la lĂ©gumineuse Retama monosperma. Notre Ă©tude rĂ©vĂšle que RmBm31 est une bactĂ©rie endophyte produisant de l'IAA et possĂ©dant un grand nombre de gĂšnes associĂ©s Ă des caractĂšres favorisant la croissance des plantes. En utilisant la plante modĂšle Arabidopsis, nous avons dĂ©montrĂ© que cette souche prĂ©sente des effets bĂ©nĂ©fiques sur la croissance et le dĂ©veloppement des plantules via la production de composĂ©s volatils. Ces effets semblent impliquer des mĂ©canismes de signalisation indĂ©pendants de l'auxine.Plants live in close relationships with complex populations of microorganisms, including rhizobacteria species commonly referred to as Plant Growth Promoting Rhizobacteria (PGPR). PGPR able to confer to plants an improved productivity but the molecular mechanisms involved in this process remain largely unknown. Using an in vitro experimental system, the model plant Arabidopsis thaliana, and the well characterized PGPR strain Pseudomonas simiae WCS417r, we have carried out a comprehensive set of phenotypic, gene expression, and biochemical analyses. Our results show PsWCS417r induces major transcriptional changes in sugar transport and in other key biological processes linked to plant growth, development and defense. Using a reverse genetic approach, we also demonstrate that AtSWEET11 and AtSWEET12, two sugar transporter genes whose expression is down-regulated by the PGPR, are functionally involved in its plant-growth promoting effects. Altogether, our findings reveal regulation of plant sugar transport plays a crucial role in determining the fate of plant-rhizobacteria interactions. We extended our study to two other PGPR and a non PGPR strain. Overall, our results show that all three bacterial strains tested are able to alter the expression of several plant sugar transporter genes (essentially genes of the AtSWEET and AtERD6-like families), either in roots or in shoot, and either in physical contact with the seedling roots or via the production of volatile compounds only. Altogether, our findings reveal conserved and strain-specific trancriptional regulation of sugar transport during plant-PGPR interactions. Lastly, we report the identification and characterization of a Bacillus megaterium endophytic strain, RmBm31, isolated from root nodules of the legume species Retama monosperma. Our study reveals RmBm31 is an IAA-producing endophytic bacterium that possess a large set of genes associated with plant growth promoting traits. Using the model plant species Arabidopsis, we demonstrate this strain display beneficial effects on plant growth and root development via the production of volatile compounds. These effects seem to involve auxin-independent signaling mechanisms
ChemInform Abstract: MICROBIOLOGICAL REDUCTION OF α,ÎČ-ETHYLENIC ALDEHYDES BY BEAUVERIA SULFURESCENS
Les Grottes et Abris préhistoriques de ThÎnes (Puy-de-DÎme)
Desrut Georges, Déret Emile. Les Grottes et Abris préhistoriques de ThÎnes (Puy-de-DÎme). In: Bulletin de la Société préhistorique de France, tome 41, n°1-3, 1944. pp. 34-38
Excrétion urinaire des glucides neutres et des glycoprotéines chez le veau préruminant recevant un aliment d'allaitement contenant de la farine de féverole
International audienc
Transcriptional regulation of plant sugar transporter genes by beneficial rhizobacteria
In their natural environment, plants live in close interaction with complex populations of microorganisms, including rhizobacteria species commonly referred to as âPlant Growth Promoting Rhizobacteriaâ (PGPR). A growing body of evidence demonstrates the importance of sugar transport in plant pathogen resistance and in plant-microorganism mutualistic symbioses. Using an in vitro experimental system, including the model plant species Arabidopsis thaliana, two PGPR strains (Pseudomonas simiae PICF7 and Burkholderia phytofirmans PsJN) and a non-PGPR strain (Escherichia coli), we conducted a comprehensive set of phenotypic and gene expression analyses to explore the role and regulation of sugar transporter genes in plant-PGPR interactions. In physical contact with the seedling roots, or solely via the emission of bacterial volatile compounds, the two PGPR strains tested improved the growth and development of the Arabidopsis seedlings and altered the expression of several plant sugar transporter genes. Our results also revealed both conserved and strain-specific transcriptional regulation mechanisms.This work was funded by the French Ministry of Higher Education, Research and Innovation (âMinistĂšre de lâEnseignement supĂ©rieur, de la Recherche et de lâInnovationâ) (AD, PhD grant), the 2015-2020 State Region Planning Contracts (CPER), the European Regional Development Fund (FEDER), and intramural funds from the French National Centre for Scientific Research (âCentre National de la Recherche Scientifiqueâ) and the University of Poitiers
Unearthing the Plant Growth-Promoting Traits of Bacillus megaterium RmBm31, an Endophytic Bacterium Isolated From Root Nodules of Retama monosperma
International audienc
Novel reductase participation in the syn-addition of hydrogen to the CC bond of enones in the cultured cells of Nicotiana tabacum
Aldehyde perception induces specific molecular responses in Laminaria digitata and affects algal consumption by a specialist grazer
International audienceSUMMARY In the marine environment, distance signaling based on waterâborne cues occurs during interactions between macroalgae and herbivores. In the brown alga Laminaria digitata from NorthâAtlantic Brittany, oligoalginates elicitation or grazing was shown to induce chemical and transcriptomic regulations, as well as emission of a wide range of volatile aldehydes, but their biological roles as potential defense or warning signals in response to herbivores remain unknown. In this context, bioassays using the limpet Patella pellucida and L. digitata were carried out for determining the effects of algal transient incubation with 4âhydroxyhexenal (4âHHE), 4âhydroxynonenal (4âHNE) and dodecadienal on algal consumption by grazers. Simultaneously, we have developed metabolomic and transcriptomic approaches to study algal molecular responses after treatments of L. digitata with these chemical compounds. The results indicated that, unlike the treatment of the plantlets with 4âHNE or dodecadienal, treatment with 4âHHE decreases algal consumption by herbivores at 100âng.ml â1 . Moreover, we showed that algal metabolome was significantly modified according to the type of aldehydes, and more specifically the metabolite pathways linked to fatty acid degradation. RNAseq analysis further showed that 4âHHE at 100âng.ml â1 can activate the regulation of genes related to oxylipin signaling pathways and specific responses, compared to oligoalginates elicitation. As kelp beds constitute complex ecosystems consisting of habitat and food source for marine herbivores, the algal perception of specific aldehydes leading to targeted molecular regulations could have an important biological role on kelps/grazers interactions