Project description:Plants are essential for life on Earth converting light into chemical energy in the form of sugars. To adjust for changes in light intensity and quality, and to become as efficient as possible in harnessing light, plants evolved multiple light receptors, signaling, and acclimation mechanisms. In addition to altering plant metabolism, development and growth, light cues sensed by some photoreceptors, such as phytochromes, are also impacting many plant responses to biotic and abiotic stresses. Central for plant responses to different stresses are reactive oxygen species (ROS) that function as key signaling molecules. Recent studies demonstrated that respiratory burst oxidase homolog (RBOH) proteins that reside at the plasma membrane and produce ROS at the apoplast play a key role in plant responses to different biotic and abiotic stresses. Here we reveal that phytochrome B (phyB) and RBOHs function as part of a key regulatory module that controls ROS production, transcript expression, and plant acclimation to excess light stress. We further show that phyB can regulate ROS production during stress even if it is restricted to the cytosol, and that phyB, RBOHD and RBOHF co-regulate thousands of transcripts in response to light stress. Surprisingly, we found that phyB is also required for ROS accumulation in response to heat, wounding, cold, and bacterial infection. Taken together, our findings reveal that phyB plays a canonical role in plant responses to biotic and abiotic stresses, regulating ROS production, and that phyB and RBOHs function in the same regulatory pathway.
Project description:mitochondrial electron transport in Arabidopsis leaves was blocked by antimycin A treatment to trigger mitochondrial production of reactive oxygen species and to study transcriptional changes in response
Project description:B. cenocepacia J2315 was exposed to heat stress and to stress form reactive oxygen species. <br>To expose the cultures to heat stress, cells were grown at 37ºC to an O.D. of 0.4 to 0.45 and then transferred into a different shaking incubator at 42.5ºC, incubated for 1 hour at 150 rpm and harvested.<br>To expose cultures to oxidative stress by reactive oxygen species, cells were grown at 37ºC to an OD of 0.5. Then t butyl hydroperoxide or hydrogen peroxide solution were added to the culture at 0.001% and 0.15% final concentration. The culture was further incubated for 15 min and then harvested. <br>The expression profiles were compared to cells grown in LB medium without exposure to stress.<br>
Project description:We were interested in investigating the transcriptome responses to exogenous applications of brassinosteroid hormone when Arabidopsis seedlings are pre-stressed with a reactive oxygen species, hydrogen peroxide. We were interested in seeing which subsets of BR-responsive gene transcripts were most affected and how BR-responsive gene transcripts responded to increasing concentrations of hydrogen peroxide both as a whole and individually.
Project description:Phosphorus (Pi) starvation prevents a good match between light energy absorption and photosynthetic carbon metabolism. Photosynthetic electron-transport chain switches to use molecular oxygen as an electron carrier, generating photo-reactive oxygen species (photo-ROS) in chloroplast. In rice (Oryza sativa), DEEP GREEN PANICLE1 (DGP1) is robustly up-regulated in response to Pi-deficiency stress. DGP1 decreases the DNA-binding activities of the photosynthetic activators GLK1/2 on the genes involved in chlorophyll biosynthesis, light harvesting and electron transport. This Pi-starvation-induced mechanism dampens electron transport rates (ETRI and ETRII) and alleviates the electron-excessive stress in mesophyll cells. Meanwhile, DGP1 hijacks glycolytic enzymes GAPC1/2/3, redirecting glucose metabolism toward pentose phosphate pathway with superfluous NADPH production. Phenotypically, light irradiation induces O2– accumulation in Pi-starved WT leaves, but was observably accelerated in dgp1 mutant and impaired in GAPCsRNAi line and glk1glk2 double mutant. Interestingly, overexpression of DGP1 in rice caused hyposensitivity to the ROS-inducers (catechin and methyl viologen) and dgp1 mutant shows a similar inhibitory growth with the WT plants. We conclude that DGP1 gene serves as a specific antagonizer against Pi-starvation-induced photo-ROS, which integrates light-absorbing and anti-oxidative systems by orchestrating transcriptional and metabolic regulations, respectively.
Project description:Phosphorus (Pi) starvation prevents a good match between light energy absorption and photosynthetic carbon metabolism. Photosynthetic electron-transport chain switches to use molecular oxygen as an electron carrier, generating photo-reactive oxygen species (photo-ROS) in chloroplast. In rice (Oryza sativa), DEEP GREEN PANICLE1 (DGP1) is robustly up-regulated in response to Pi-deficiency stress. DGP1 decreases the DNA-binding activities of the photosynthetic activators GLK1/2 on the genes involved in chlorophyll biosynthesis, light harvesting and electron transport. This Pi-starvation-induced mechanism dampens electron transport rates (ETRI and ETRII) and alleviates the electron-excessive stress in mesophyll cells. Meanwhile, DGP1 hijacks glycolytic enzymes GAPC1/2/3, redirecting glucose metabolism toward pentose phosphate pathway with superfluous NADPH production. Phenotypically, light irradiation induces O2– accumulation in Pi-starved WT leaves, but was observably accelerated in dgp1 mutant and impaired in GAPCsRNAi line and glk1glk2 double mutant. Interestingly, overexpression of DGP1 in rice caused hyposensitivity to the ROS-inducers (catechin and methyl viologen) and dgp1 mutant shows a similar inhibitory growth with the WT plants. We conclude that DGP1 gene serves as a specific antagonizer against Pi-starvation-induced photo-ROS, which integrates light-absorbing and anti-oxidative systems by orchestrating transcriptional and metabolic regulations, respectively.
Project description:We were interested in investigating the transcriptome responses to exogenous applications of brassinosteroid hormone when Arabidopsis seedlings are pre-stressed with a reactive oxygen species, hydrogen peroxide. We were interested in seeing which subsets of BR-responsive gene transcripts were most affected and how BR-responsive gene transcripts responded to increasing concentrations of hydrogen peroxide both as a whole and individually. Liquid culture Arabidopsis seedlings are grown under standard conditions. Hydrogen peroxide is added at various concentrations to pre-stress the seedlings. Following this pretreatment, the seedlings are then treated with brassinosteroid (BR) hormone (epi-brassinolide, BL). Following this treatment, seedlings are harvested and total RNA is extracted for genome-wide transcriptome analysis.
Project description:To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a novel bZIP transcription factor, which seems to control its own expression as well as that of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was shown to be essential for GSTS1 overexpression in sor1 and for induction by increased levels of lipophilic reactive electrophile species (RES) suggesting that it functions as an electrophile response element (ERE). RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that a RES-stimulated and SOR1-mediated response of detoxification genes is part of the singlet oxygen-induced acclimation process in C. reinhardtii. The sor1 mutant isolated in a screen for singlet oxygen resistant mutants and the corresponding wild-type strain 4A+ were grown in a 12 h light dark cycle for several days before total RNA was extracted 6 h after the light came on.
Project description:To identify components involved in the signal transduction and activation of the singlet oxygen-mediated response, a mutant selection was performed. This led to the isolation of the singlet oxygen resistant 1 (sor1) mutant, which is more tolerant to singlet oxygen-producing chemicals and shows a constitutively higher expression of GPXH and GSTS1. Map-based cloning revealed that the SOR1 gene encodes a novel bZIP transcription factor, which seems to control its own expression as well as that of a large number of oxidative stress response and detoxification genes. In the promoter region of many of these genes a highly conserved 8-bp palindromic sequence element was found to be enriched. This element was shown to be essential for GSTS1 overexpression in sor1 and for induction by increased levels of lipophilic reactive electrophile species (RES) suggesting that it functions as an electrophile response element (ERE). RES can be formed after singlet oxygen-induced lipid peroxidation, indicating that a RES-stimulated and SOR1-mediated response of detoxification genes is part of the singlet oxygen-induced acclimation process in C. reinhardtii.
Project description:Cellular membrane proteins are a critical part of the host defense mechanisms against infection and intracellular survival of Listeria monocytogenes. The complex spatiotemporal regulation of bacterial infection by various membrane proteins has been challenging to study. Here, using mass spectrometry analyses, we depicted the dynamic expression landscape of membrane proteins upon L. monocytogenes infection in dendritic cells. We showed that Dynein light chain 1 (Dynll1) formed a persistent complex with the mitochondrial cytochrome oxidase, Cox4i1 that is disturbed by pathogen insult. We discovered that the dissociation of the Dynll1-Cox4i1 complex is required for the release of mitochondrial reactive oxygen species and serves as a regulator of intracellular proliferation of Listeria monocytogenes. Our study shows that Dynll1 is an inhibitor of mitochondrial reactive oxygen species and can serve as a potential molecular drug target for antibacterial treatment.