Project description:Volatiles of certain rhizobacteria can cause growth inhibitory effects on plants/ Arabidopsis thaliana. How these effects are initiated and which mechanisms are enrolled is not yet understood. Obviously the plant can survive/live with the bacteria in the soil, which suggest the existance of a regulatory mechanism/network that provide the possibility for coexistance with the bacteria. To shed light on this regulatory mechanism/network we performed a microarray anlaysis of Arabidopsis thaliana co-cultivated with two different rhizobacteria strains. In this study we used the ATH1 GeneChip microarray to investigate the transcriptional response of 4 to 5 days old Arabidopsis thaliana seedlings at 6 h, 12 h and 24 h exposure to volatiles of the rhizobacteria Serratia plymuthica HRO-C48 or Stenotrophomonas maltophilia R3089.
Project description:Volatiles of certain rhizobacteria can cause growth inhibitory effects on plants/ Arabidopsis thaliana. How these effects are initiated and which mechanisms are enrolled is not yet understood. Obviously the plant can survive/live with the bacteria in the soil, which suggest the existance of a regulatory mechanism/network that provide the possibility for coexistance with the bacteria. To shed light on this regulatory mechanism/network we performed a microarray anlaysis of Arabidopsis thaliana co-cultivated with two different rhizobacteria strains. In this study we used the ATH1 GeneChip microarray to investigate the transcriptional response of 4 to 5 days old Arabidopsis thaliana seedlings at 6 h, 12 h and 24 h exposure to volatiles of the rhizobacteria Serratia plymuthica HRO-C48 or Stenotrophomonas maltophilia R3089. Seedlings from Arabidopsis thaliana were harvested at different time points at exposure to volatiles of two different strains of bacteria. Samples were taken at the start of the experiment (T0) and after 6, 12 and 24 hours (T6, T12, T24 respectively). Two biological replicates from pooled seedlings (from 5 plates, from the respective time points) were used for RNA extraction and hybridization on Affymetrix microarrays (ATH1 GeneChip; GEO accsession GPL198).
Project description:Arabidopsis thaliana 4-day-old seedlings were treated with the plant growth promoting rhizobacteria Caulobacter RHG1 or the neutral bacteria Bacillus sp. At 12 and 48 hours after treatment, roots were harvested, RNA was extracted and RNA-Seq data were generated. The goal of this experiment was to detect changes at the transcript level that were specific for the plant growth promoting rhizobacteria RHG1.
Project description:Unlike pathogens that trigger plant defense responses, beneficial microbes are compatible with plants. One possible reason for the compatibility is that the microbial factors from beneficial microbes are inert in that they do not trigger plant defense responses. Little is known about the mechanisms underlying this seemingly inert relation. Here we report that Arabidopsis lacking the gene Growth-Promotion 1 (GP1) becomes defensive to microbial volatiles from Bacillus amyloliqueficiens strain GB03, a beneficial rhizobacterium. The gp1 mutant was isolated in a forward genetic screen for mutants that show defectiveness in GB03-triggered plant inducible vigor. GP1 encodes a stearoyl-ACP desaturase that catalyzes the desaturation of stearic acid (18:0) to oleic acid (18:1). Consistently, plant inducible vigor was also impaired by chemical enhancement of 18:1 catabolism, while genetic disruption of 18:1 catabolism largely restored the inducible vigor in gp1. When exposed to GB03-emitted microbial volatiles (GMVs), wild type plants showed transcriptional up-regulation of growth-promoting processes and down-regulation of defense responses; in contrast, the gp1 transcriptome displayed elevated defense responses when treated with GMVs. Meanwhile disruption of salicylic acid-mediated defense partially restored plant inducible vigor in gp1. Microbiota profiling revealed that GP1 dysfunction alters the assemblage of plant-associated rhizobacteria communities, including a reduction in the Bacillaceae family that is known to contain many beneficial rhizobacteria species. Consistently, gp1 mutants showed severely impaired root colonization of GB03. Our findings suggest that GP1 prevents the plant defense system from being mistakenly activated by non-pathogenic microbial factors, thereby allowing mutualistic association between the plant and beneficial microbes.
Project description:ra04-07_pgpr - trancriptional response to 3 rhizobacteria - Experiment 1 : Which genes are up- or down-regulated in Arabidopsis thaliana cultivated in vitro with increased lateral root development in response to Phyllobacterium STM196 inoculation. Experiment 2 : Which genes are up- or down-regulated during the ISR triggered by a rhizobacteria, in comparison with those affected by a pathogenic interaction. Experiment 3 : which genes are specifically induced or repressed in Arabidopsis thaliana by inoculation of the soil with a PGPR vs a bacteria that has the ability to trigger nodule formation in a Legume. - Seeds of wild-type Arabidopsis thaliana (ecotype Columbia) were surface-sterilized and sawn on agar mineral medium. Four days after storage in the dark at 4degreeC, seedlings were cultivated 6 days in a growth chamber (16 h daily, 20-22degreeC) and then transferred on soil inoculated or not with 108 cfu.g-1 of Mesorhizobium loti, or 108 cfu.g-1 of Phyllobacterium STM196, or 107 cfu.g-1 of Bradyrhizobium ORS278. Keywords: treated vs untreated comparison
Project description:Plant volatiles can mediate plant-plant communication in the sense that plants attacked by herbivores can signal their unattacked neighbors of danger by emitting HIPVs. We call this the priming effect. Since the plant defense response is a systematic process involving numerous pathways and genes,to characterize the priming process, a time course study using a genome-wide microarray may provide more accurate information about the priming process. Furthermore, to what extent do the priming process and direct defense share similar gene expression profiles or pathways are also not clear. We used microarray to detect the priming effect of plant volatiles to healthy Arabidopsis thaliana, and the effect of direct leafminer feeding to Arabidopsis thalianas.
Project description:Plant volatiles can mediate plant-plant communication in the sense that plants attacked by herbivores can signal their unattacked neighbors of danger by emitting HIPVs. We call this the priming effect. Since the plant defense response is a systematic process involving numerous pathways and genes,to characterize the priming process, a time course study using a genome-wide microarray may provide more accurate information about the priming process. Furthermore, to what extent do the priming process and direct defense share similar gene expression profiles or pathways are also not clear. We used microarray to detect the priming effect of plant volatiles to healthy Arabidopsis thaliana, and the effect of direct leafminer feeding to Arabidopsis thalianas. A system using Lima bean plants, from which HIPVs can be effectively induced by leafminer feeding, as emitters and Arabidopsis thaliana as receivers is used to track the priming process between neighbor plants. The Arabisopsis thaliana seedlings were treated by volatiles from leafminer fed lima bean for 24h or 48h for RNA extraction and hybridization on Affymetrix microarrays. The Arabisopsis thaliana seedlings fed by leafminer directly were also collected The for RNA extraction and hybridization on Affymetrix micorarrays. We want to explore the response of Arabidopsis thaliana to priming volatiles during a 24h-48h time course. We also want to compare the effect of priming and direct leafminer feeding.
Project description:We report the banana transcriptome profile in response to two distinct growth-promoting rhizobacteria, Bacillus amyloliquefaciens and Pseudomonas fluorescens. The goal of our study is to identify plant genes differentially regulated by rhizobacteria-plant interaction along time. At the same time, we show that despite these two rhizobacteria regulate distinct sets of genes, the same functional categories has been over-represented, such as transcription factor activity, response to stress and metabolic processes.