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Conrath, Uwe; Thulke, Oliver; Katz, V. A.; Schwindling, Sandra L; Kohler, Annegret

doi:10.1023/a:1008768516313

Cited by 156 publications

(19 citation statements)

References 50 publications

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“…Together these results suggest that sensitization of stress-regulated pathways for rapid and high gene expression may be one of the essential elements in stress acclimation. Salicylic acid has been mainly implicated in potentiation of gene expression (44), although other signal molecules, such as jasmonic acid, systemin, ethylene, and ␤-aminobutyric acid, have been shown to play a similar role (46)(47)(48). Here we show that pretreatment with sublethal levels of MV sensitized plants for higher gene expression, thus indicating that AOS can play a role in potentiation of gene expression as well.…”

Section: Discussionmentioning

confidence: 53%

“…Such expression levels are never reached in nonacclimated leaf discs, even after prolonged exposure to MV, showing that pretreatment with a sublethal dose of oxidative stress sensitizes plants to much stronger gene induction during oxidative stress. Potentiation of the expression of a few defense genes has been observed on prior stress exposure or stress hormone pretreatment and has usually been correlated with the establishment of tolerance against biotic and abiotic stresses in such pretreated plants (44)(45)(46)(47). Here, we have shown that acclimation to oxidative stress involves concerted potentiation of different sets of defense genes.…”

Section: Discussionmentioning

confidence: 61%

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Comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress

Vranová

Atichartpongkul

Villarroel

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

163

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The molecular mechanisms by which plants acclimate to oxidative stress are poorly understood. To identify the processes involved in acclimation, we performed a comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress. Combining mRNA differential display and cDNA array analysis, we estimated that at least 95 genes alter their expression in tobacco leaves acclimated to oxidative stress, of which 83% are induced and 17% repressed. Sequence analysis of 53 sequence tags revealed that, in addition to antioxidant genes, genes implicated in abiotic and biotic stress defenses, cellular protection and detoxification, energy and carbohydrate metabolism, de novo protein synthesis, and signal transduction showed altered expression. Expression of most of the genes was enhanced, except for genes associated with photosynthesis and light-regulated processes that were repressed. During acclimation, two distinct groups of coregulated genes (''early-'' and ''late-response'' gene regulons) were observed, indicating the presence of at least two different gene induction pathways. These two gene regulons also showed differential expression patterns on an oxidative stress challenge. Expression of ''late-response'' genes was augmented in the acclimated leaf tissues, whereas expression of ''early-response'' genes was not. Together, our data suggest that acclimation to oxidative stress is a highly complex process associated with broad gene expression adjustments. Moreover, our data indicate that in addition to defense gene induction, sensitization of plants for potentiated gene expression might be an important factor in oxidative stress acclimation. E xposure to sublethal biotic and abiotic stresses renders plants more tolerant to a subsequent, normally lethal, dose of the same stress, and this phenomenon is referred to as acclimation or acquired resistance (1-3). This induced stress resistance is not restricted to the same type of stress, and cross-tolerance between different stresses has been reported (4-6). Because many stress conditions provoke cellular redox imbalances, it has been suggested that oxidative stress defenses contribute to induced abiotic and biotic stress tolerance and are a central crosstolerance-mediating component (7). This notion is also supported by the fact that plants acclimated to heat or cold as well as plants showing acquired resistance to pathogens are all more tolerant to oxidative stress (8-10). Antioxidant defense responses have long been associated mainly with enhanced antioxidant enzyme activity and increased levels of antioxidant metabolites, such as ascorbic acid, glutathione, ␣-tocopherol, and carotenoids (11). More recently, induction of small heat shock proteins, the cellular protection gene glutatione Stransferase (GST), and the pathogenesis-related gene PR2 have also been associated with acquisition of oxidative stress tolerance (9,12,13).Acclimatory responses to various oxidants have been extensively studied in bacteria and yeast. In bacteria, at least 8...

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Section: Discussionmentioning

confidence: 53%

Section: Discussionmentioning

confidence: 61%

Comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress

Vranová

Atichartpongkul

Villarroel

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

163

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“…As major components of the outer membrane, they are involved in the protection of bacterial cells, contributing to reduce the membrane permeability and thus allowing growth of bacteria in the unfavorable conditions of the plant environment (11). Moreover, LPSs can be recognized by plants to elicit or potentiate plant defense-related responses (12,13). One of the most widely studied effects of LPSs on plant cells is their ability to prevent the hypersensitive response (HR) induced in plants by avirulent bacteria.…”

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confidence: 99%

Structural Analysis and Involvement in Plant Innate Immunity of Xanthomonas axonopodis pv. citri Lipopolysaccharide

Casabuono

Petrocelli

Ottado

et al. 2011

Journal of Biological Chemistry

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Xanthomonas axonopodis pv. citri (Xac) causes citrus canker, provoking defoliation and premature fruit drop with concomitant economical damage. In plant pathogenic bacteria, lipopolysaccharides are important virulence factors, and they are being increasingly recognized as major pathogen-associated molecular patterns for plants. In general, three domains are recognized in a lipopolysaccharide: the hydrophobic lipid A, the hydrophilic O-antigen polysaccharide, and the core oligosaccharide, connecting lipid A and O-antigen. In this work, we have determined the structure of purified lipopolysaccharides obtained from Xanthomonas axonopodis pv. citri wild type and a mutant of the O-antigen ABC transporter encoded by the wzt gene. High pH anion exchange chromatography and matrix-assisted laser desorption/ionization mass spectrum analysis were performed, enabling determination of the structure not only of the released oligosaccharides and lipid A moieties but also the intact lipopolysaccharides. The results demonstrate that Xac wild type and Xacwzt LPSs are composed mainly of a penta-or tetra-acylated diglucosamine backbone attached to either two pyrophosphorylethanolamine groups or to one pyrophosphorylethanolamine group and one phosphorylethanolamine group. The core region consists of a branched oligosaccharide formed by Kdo 2 Hex 6 GalA 3 Fuc3NAcRha 4 and two phosphate groups. As expected, the presence of a rhamnose homo-oligosaccharide as O-antigen was determined only in the Xac wild type lipopolysaccharide. In addition, we have examined how lipopolysaccharides from Xac function in the pathogenesis process. We analyzed the response of the different lipopolysaccharides during the stomata aperture closure cycle, the callose deposition, the expression of defense-related genes, and reactive oxygen species production in citrus leaves, suggesting a functional role of the O-antigen from Xac lipopolysaccharides in the basal response.

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“…As major components of the outer membrane, LPSs are involved in the protection of bacterial cell, contributing to reduce the membrane permeability and thus allowing growth of bacterium in the unfavorable conditions of the plant environment (7). In contrast, LPSs can be recognized by plants to elicit or potentiate plant defense-related responses as part of a group of general elicitors that include flagellin and periplasmic oligosaccharides (8,9). One of the most widely studied effects of LPSs on plant cells is their ability to prevent the hypersensitive response (HR) induced in plants by avirulent bacteria.…”

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confidence: 99%

The Elicitation of Plant Innate Immunity by Lipooligosaccharide of Xanthomonas campestris

Silipo¹,

Molinaro²,

Sturiale³

et al. 2005

Journal of Biological Chemistry

177

165

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Lipopolysaccharides (LPSs) and lipooligosaccharides (LOSs) are major components of the cell surface of Gram-negative bacteria with diverse roles in bacterial pathogenesis of animals and plants that include elicitation of host defenses. Little is known about the mechanisms of perception of these molecules by plants and about the associated signal transduction pathways that trigger plant immunity. Here we address the issue of the molecular basis of elicitation of plant defenses through the structural determination of the LOS of the plant pathogen Xanthomonas campestris pv. campestris strain 8004 and examination of the effects of LOS and fragments obtained by chemical treatments on the immune response in Arabidopsis thaliana. The structure shows a strong accumulation of negatively charged groups in the lipid A-inner core region and has a number of novel features, including a galacturonyl phosphate attached at a 3-deoxy-D-manno-oct-2-ulosonic acid residue and a unique phosphoramide group in the inner core region. Intact LOS and the lipid A and core oligosaccharides derived from it were all able to induce the defense-related genes PR1 and PR2 in Arabidopsis and to prevent the hypersensitive response caused by avirulent bacteria. Although LOS induced defense-related gene transcription in two temporal phases, the core oligosaccharide induced only the earlier phase, and lipid A induced only the later phase. These findings suggest that plant cells can recognize lipid A and core oligosaccharide structures within LOS to trigger defensive cellular responses and that this may occur via two distinct recognition events. Lipopolysaccharides (LPSs)2 are ubiquitous and vital components of the cell surface of Gram-negative bacteria (1, 2). They are amphiphilic macromolecules composed of a hydrophilic heteropolysaccharide (comprising the core oligosaccharide and O-specific polysaccharide or O-chain) covalently linked to a lipophilic moiety termed lipid A, which anchors these macromolecules to the outer membrane. LPSs not possessing the O-chain are termed rough LPSs or lipooligosaccharides (LOSs).In animal and insect cells, innate immune defenses are triggered by the perception of pathogen-associated molecular patterns (PAMPs), conserved and generally indispensable microbial structures including LPSs. The recognition of PAMPs by these cells is often mediated by leucine-rich repeat proteins such as Toll in Drosophila and the Toll-like receptors in mammals (3-6). Recognition of LPSs occurs through the lipid A moiety, which is responsible for most of the biological effects of LPS in animals. Lipid A toxicity in animals strongly depends on its structure and is also influenced by the covalently linked core region, which possesses immunogenic properties (1, 2).LPSs apparently have diverse roles in bacterial pathogenesis of plants. As major components of the outer membrane, LPSs are involved in the protection of bacterial cell, contributing to reduce the membrane permeability and thus allowing growth of bacterium in the unfavorable conditi...

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Untitled

Cited by 156 publications

References 50 publications

Comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress

Comprehensive analysis of gene expression in Nicotiana tabacum leaves acclimated to oxidative stress

Structural Analysis and Involvement in Plant Innate Immunity of Xanthomonas axonopodis pv. citri Lipopolysaccharide

The Elicitation of Plant Innate Immunity by Lipooligosaccharide of Xanthomonas campestris

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