scholarly journals Exposure to Cadmium Elevates Expression of Genes in the OxyR and OhrR Regulons and Induces Cross-Resistance to Peroxide Killing Treatment in Xanthomonas campestris

2005 ◽  
Vol 71 (4) ◽  
pp. 1843-1849 ◽  
Author(s):  
Peerakan Banjerdkij ◽  
Paiboon Vattanaviboon ◽  
Skorn Mongkolsuk
Keyword(s):  
Induced Resistance ◽  
Stress Responses ◽  
Xanthomonas Campestris ◽  
Cadmium Toxicity ◽  
Cross Resistance ◽  
Organic Hydroperoxide ◽  
Alkyl Hydroperoxide ◽  
Expression Of Genes ◽  
Low Concentrations ◽  
Peroxide Stress

ABSTRACT Cadmium is an important heavy metal pollutant. For this study, we investigated the effects of cadmium exposure on the oxidative stress responses of Xanthomonas campestris, a soil and plant pathogenic bacterium. The exposure of X. campestris to low concentrations of cadmium induces cross-protection against subsequent killing treatments with either H2O2 or the organic hydroperoxide tert-butyl hydroperoxide (tBOOH), but not against the superoxide generator menadione. The cadmium-induced resistance to peroxides is due to the metal's ability to induce increased levels of peroxide stress protective enzymes such as alkyl hydroperoxide reductase (AhpC), monofunctional catalase (KatA), and organic hydroperoxide resistance protein (Ohr). Cadmium-induced resistance to H2O2 is dependent on functional OxyR, a peroxide-sensing transcription regulator. Cadmium-induced resistance to tBOOH shows a more complex regulatory pattern. The inactivation of the two major sensor-regulators of organic hydroperoxide, OxyR and OhrR, only partially inhibited cadmium-induced protection against tBOOH, suggesting that these genes do have some role in the process. However, other, as yet unknown mechanisms are involved in inducible organic hydroperoxide protection. Furthermore, we show that the cadmium-induced peroxide stress response is mediated by the metal's ability to predominately cause an increase in intracellular concentrations of organic hydroperoxide and, in part, H2O2. Analyses of various mutants of peroxide-metabolizing enzymes suggested that this increase in organic hydroperoxide levels is, at least in part, responsible for cadmium toxicity in Xanthomonas.

scholarly journals Identification and Characterization of a New Organic Hydroperoxide Resistance (ohr) Gene with a Novel Pattern of Oxidative Stress Regulation from Xanthomonas campestrispv. phaseoli

1998 ◽  
Vol 180 (10) ◽  
pp. 2636-2643 ◽  
Author(s):  
Skorn Mongkolsuk ◽  
Wipa Praituan ◽  
Suvit Loprasert ◽  
Mayuree Fuangthong ◽  
Sangpen Chamnongpol
Keyword(s):  
Xanthomonas Campestris ◽  
Expression Patterns ◽  
The Novel ◽  
Organic Hydroperoxide ◽  
Alkyl Hydroperoxide ◽  
Growth Inhibitory ◽  
Low Concentrations ◽  
Organic Hydroperoxides ◽  
New Type ◽  
Increased Sensitivity

ABSTRACT We have isolated a new organic hydroperoxide resistance (ohr) gene from Xanthomonas campestris pv. phaseoli. This was done by complementation of anEscherichia coli alkyl hydroperoxide reductase mutant with an organic hydroperoxide-hypersensitive phenotype. ohrencodes a 14.5-kDa protein. Its amino acid sequence shows high homology with several proteins of unknown function. An ohr mutant was subsequently constructed, and it showed increased sensitivity to both growth-inhibitory and killing concentrations of organic hydroperoxides but not to either H2O2 or superoxide generators. No alterations in sensitivity to other oxidants or stresses were observed in the mutant. ohr had interesting expression patterns in response to low concentrations of oxidants. It was highly induced by organic hydroperoxides, weakly induced by H2O2, and not induced at all by a superoxide generator. The novel regulation pattern of ohrsuggests the existence of a second organic hydroperoxide-inducible system that differs from the global peroxide regulator system, OxyR. Expression of ohr in various bacteria tested conferred increased resistance totert-butyl hydroperoxide killing, but this was not so for wild-type Xanthomonas strains. The organic hydroperoxide hypersensitivity of ohr mutants could be fully complemented by expression of ohr or a combination of ahpC and ahpF and could be partially complemented by expression ahpC alone. The data suggested that Ohr was a new type of organic hydroperoxide detoxification protein.

scholarly journals OhrR Is a Repressor of ohrA, a Key Organic Hydroperoxide Resistance Determinant in Bacillus subtilis

2001 ◽  
Vol 183 (14) ◽  
pp. 4134-4141 ◽  
Author(s):  
Mayuree Fuangthong ◽  
Sopapan Atichartpongkul ◽  
Skorn Mongkolsuk ◽  
John D. Helmann
Keyword(s):  
Reactive Oxygen Species ◽  
Bacillus Subtilis ◽  
Stress Responses ◽  
Xanthomonas Campestris ◽  
Reactive Oxygen ◽  
Organic Peroxide ◽  
Repeat Sequence ◽  
Oxygen Species ◽  
Organic Hydroperoxide ◽  
Complex Adaptive

ABSTRACT Bacillus subtilis displays a complex adaptive response to the presence of reactive oxygen species. To date, most proteins that protect against reactive oxygen species are members of the peroxide-inducible PerR and ςB regulons. We investigated the function of two B. subtilis homologs of theXanthomonas campestris organic hydroperoxide resistance (ohr) gene. Mutational analyses indicate that bothohrA and ohrB contribute to organic peroxide resistance in B. subtilis, with the OhrA protein playing the more important role in growing cells. Expression ofohrA, but not ohrB, is strongly and specifically induced by organic peroxides. Regulation ofohrA requires the convergently transcribed gene,ohrR, which encodes a member of the MarR family of transcriptional repressors. In an ohrR mutant,ohrA expression is constitutive, whereas expression of the neighboring ohrB gene is unaffected. Selection for mutant strains that are derepressed for ohrA transcription identifies a perfect inverted repeat sequence that is required for OhrR-mediated regulation and likely defines an OhrR binding site. Thus,B. subtilis contains at least three regulons (ςB, PerR, and OhrR) that contribute to peroxide stress responses.

scholarly journals Xanthomonas transcriptome inside cauliflower hydathodes reveals bacterial virulence strategies and physiological adaptation at early infection stages

2021 ◽  
Author(s):  
Julien S. Luneau ◽  
Aude Cerutti ◽  
Brice Roux ◽  
Sébastien Carrère ◽  
Marie-Françoise Jardinaud ◽  
...  
Keyword(s):  
Stress Responses ◽  
Xanthomonas Campestris ◽  
Plant Immunity ◽  
Adaptive Strategy ◽  
Physiological Adaptation ◽  
Transcriptional Reprogramming ◽  
Expression Of Genes ◽  
Rot Disease ◽  
Tissue Alterations ◽  
Type Three Secretion

AbstractXanthomonas campestris pv. campestris (Xcc) bacterium is a seed-transmitted vascular pathogen causing black rot disease on cultivated and wild Brassicaceae. Xcc enters the plant tissues preferentially via hydathodes which are organs localized at leaf margins. In order to decipher both physiological and virulence strategies deployed by Xcc during early stages of infection, the transcriptomic profile of Xcc was analyzed three days after entry into cauliflower hydathodes. Despite the absence of visible plant tissue alterations and a bacterial biotrophic lifestyle, 18% of Xcc genes undergo a transcriptional reprogramming, including a striking repression of chemotaxis and motility functions. Xcc full repertoire of virulence factors was not yet activated but the expression of the 95-gene HrpG regulon, including genes coding for the type three secretion machinery important for suppression of plant immunity, was induced. The expression of genes involved in metabolic adaptations such as catabolism of plant compounds, transport functions, sulfur and phosphate metabolism was upregulated while limited stress responses were observed three days post infection. These transcriptomic observations give information about the nutritional and stress status of bacteria during the early biotrophic infection stages and help to decipher the adaptive strategy of Xcc to the hydathode environment.

Induced resistance in rice against insects

2007 ◽  
Vol 97 (4) ◽  
pp. 327-335 ◽  
Author(s):  
R. Karban ◽  
Y. Chen
Keyword(s):  
Induced Resistance ◽  
Insect Pests ◽  
Rice Genome ◽  
Cross Resistance ◽  
Induced Responses ◽  
Gall Midges ◽  
Expression Of Genes ◽  
Dicotyledonous Plants ◽  
Induce Resistance ◽  
Phloem Feeding

AbstractVaccinations are the mainstay of western preventive medicine, and they have been used to protect some crops against disease and insect pests. We consider rice as a model for protection using induced resistance since it is one of the most important staple crops and there have been significant new developments in: cross-resistance among rice insects, chemical pathways involved in induced resistance, sequencing the rice genome and expression of genes conferring resistance against rice insect pests. Insect attack has been found to cause lesions that kill planthopper eggs and early stages of gall midges. Damaged plants released volatiles that made them less likely to be chosen by planthoppers and more attractive to parasitoids. Chemical elicitors have been developed for dicotyledonous plants and these can induce resistance in rice, although rice does not fit models developed to explain signalling in dicots. For example, salicylic acid did not increase in rice after infection by pathogens and did not appear to be the mobile signal for induced resistance against pathogens although it was involved in induced responses to phloem-feeding insects. Jasmonic acid acted as a signal in some induced responses to pathogens as well as chewing insects. Many of the genes associated with induced resistance in rice have recently been mapped, and techniques are being developed to incorporate them into the genome of cultivated varieties. Attempts to control insect pests of rice will affect interactions with pathogens, predators and parasites, and other organisms in this agroecosystem.

Effect of C6-Volatiles on Bioluminescent Plant Pathogens

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 557d-557
Author(s):  
Jennifer Warr ◽  
Fenny Dane ◽  
Bob Ebel
Keyword(s):  
Biological Activity ◽  
Bacterial Growth ◽  
Xanthomonas Campestris ◽  
Plant Pathogens ◽  
Genetically Engineered ◽  
The Other ◽  
Computer Assisted ◽  
Signal Molecules ◽  
Low Concentrations

C6 volatile compounds are known to be produced by the plant upon pathogen attack or other stress-related events. The biological activity of many of these substances is poorly understood, but some might produce signal molecules important in host–pathogen interactions. In this research we explored the possibility that lipid-derived C6 volatiles have a direct effect on bacterial plant pathogens. To this purpose we used a unique tool, a bacterium genetically engineered to bioluminesce. Light-producing genes from a fish-associated bacterium were introduced into Xanthomonas campestris pv. campestris, enabling nondestructive detection of bacteria in vitro and in the plant with special computer-assisted camera equipment. The effects of different C6 volatiles (trans-2 hexanal, trans-2 hexen-1-ol and cis-3 hexenol) on growth of bioluminescent Xanthomonas campestris were investigated. Different volatile concentrations were used. Treatment with trans-2 hexanal appeared bactericidal at low concentrations (1% and 10%), while treatments with the other volatiles were not inhibitive to bacterial growth. The implications of these results with respect to practical use of trans-2 hexanal in pathogen susceptible and resistant plants will be discussed.

scholarly journals Hormetic Concentrations of Hydrogen Peroxide but Not Ethanol Induce Cross-Adaptation to Different Stresses in Budding Yeast

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Halyna M. Semchyshyn
Keyword(s):  
Hydrogen Peroxide ◽  
Dose Response ◽  
Budding Yeast ◽  
Regulatory Protein ◽  
Colony Growth ◽  
Inhibitory Effect ◽  
Cross Resistance ◽  
Mild Stress ◽  
Low Concentrations ◽  
Cross Adaptation

The biphasic-dose response of microorganisms to hydrogen peroxide is a phenomenon of particular interest in hormesis research. In different animal models, the dose-response curve for ethanol is also nonlinear showing an inhibitory effect at high doses but a stimulatory effect at low doses. In this study, we observed the hormetic-dose response to ethanol in budding yeastS. cerevisiae. Cross-protection is a phenomenon in which exposure to mild stress results in the acquisition of cellular resistance to lethal stress induced by different factors. Since both hydrogen peroxide and ethanol at low concentrations were found to stimulate yeast colony growth, we evaluated the role of one substance in cell cross-adaptation to the other substance as well as some weak organic acid preservatives. This study demonstrates that, unlike ethanol, hydrogen peroxide at hormetic concentrations causes cross-resistance ofS. cerevisiaeto different stresses. The regulatory protein Yap1 plays an important role in the hormetic effects by low concentrations of either hydrogen peroxide or ethanol, and it is involved in the yeast cross-adaptation by low sublethal doses of hydrogen peroxide.

scholarly journals A Simple and Low-Cost Strategy to Improve Conidial Yield and Stress Resistance of Trichoderma guizhouense through Optimizing Illumination Conditions

2022 ◽  
Vol 8 (1) ◽  
pp. 50
Author(s):  
Yifan Li ◽  
Xiya Meng ◽  
Degang Guo ◽  
Jia Gao ◽  
Qiwei Huang ◽  
...  
Keyword(s):  
Blue Light ◽  
Stress Responses ◽  
Stress Resistance ◽  
Low Cost ◽  
Hog Pathway ◽  
Precise Control ◽  
Blue Light Receptor ◽  
Expression Of Genes ◽  
Low Cost Strategy ◽  
Stress Related Genes

Light is perceived by photoreceptors in fungi and further integrated into the stress-activated MAPK HOG pathway, and thereby potentially activates the expression of genes for stress responses. This indicates that the precise control of light conditions can likely improve the conidial yield and stress resistance to guarantee the low cost and long shelf life of Trichoderma-based biocontrol agents and biofertilizers. In this study, effects of wavelengths and intensities of light on conidial yield and stress tolerance to osmotic, oxidative and pH stresses in Trichoderma guizhouense were investigated. We found that 2 μmol photons/(m2 × s) of blue light increased the conidial yield more than 1000 folds as compared to dark condition and simultaneously enhanced conidial stress resistance. The enhanced conidial stress resistance is probably due to the upregulated stress-related genes in blue light, which is under the control of the blue light receptor BLR1 and the MAP kinase HOG1.

scholarly journals Early life adversity and the epigenetic programming of hypothalamic-pituitary-adrenal function

2014 ◽  
Vol 16 (3) ◽  
pp. 321-333 ◽  
Keyword(s):  
Stress Responses ◽  
Childhood Adversity ◽  
Adrenal Function ◽  
Early Life Adversity ◽  
Hypothalamic Pituitary Adrenal ◽  
Expression Of Genes ◽  
Epigenetic Programming ◽  
Social Adversity ◽  
Wide Range ◽  
Nonhuman Species

We review studies with human and nonhuman species that examine the hypothesis that epigenetic mechanisms, particularly those affecting the expression of genes implicated in stress responses, mediate the association between early childhood adversity and later risk of depression. The resulting studies provide evidence consistent with the idea that social adversity, particularly that involving parent-offspring interactions, alters the epigenetic state and expression of a wide range of genes, the products of which regulate hypothalamic-pituitary-adrenal function. We also address the challenges for future studies, including that of the translation of epigenetic studies towards improvements in treatments.

Temephos-induced resistance in Aedes aegypti and its cross-resistance studies to certain insecticides from India

2009 ◽  
Vol 105 (1) ◽  
pp. 57-63 ◽  
Author(s):  
S. N. Tikar ◽  
Arkaja Kumar ◽  
G. B. K. S. Prasad ◽  
Shri Prakash
Keyword(s):  
Aedes Aegypti ◽  
Induced Resistance ◽  
Cross Resistance
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