The role of lipopolysaccharides in induction of plant defence responses (original) (raw)
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Journal of Endotoxin Research, 2007
Plants in nature are involved in a variety of interactions with Gram-negative bacteria that may be of benefit or detriment to the host. In symbiotic interactions between leguminous plants and Gram-negative bacteria of the Rhizobiaceae, atmospheric nitrogen fixed by the bacteria within specialized plant-elaborated structures is made available to the host. Beneficial interactions of plants with Pseudomonas spp. in the rhizosphere (the zone of the soil directly influenced by the roots and characterized by increased microbiological activity) can lead to enhanced plant growth, increased plant disease resistance and increased resistance to environmental stresses. Conversely, pathogens belonging to the Gram-negative genera Agrobacterium, Erwinia, Pseudomonas, Ralstonia, Xanthomonas, and Xylella are responsible for some of the most serious diseases in cultivated crops. As ubiquitous and vital components of the cell surface of Gram-negative bacteria, lipopolysaccharides (LPSs) have multiple roles in these various plant-microbe interactions. LPS contributes to the reduced permeability of the Gram-negative outer membrane. This barrier function allows growth of bacteria in unfavourable conditions that
The Plant Journal, 2002
Lipopolysaccharide (LPS) is a ubiquitous component of Gram-negative bacteria which has a number of diverse biological effects on eukaryotic cells. In contrast to the large body of work in mammalian and insect cells, the effects of LPS on plant cells have received little attention. LPS can induce defenserelated responses in plants, but in many cases these direct effects are weak. Here we have examined the effects of prior inoculation of LPS on the induction of plant defense-related responses by phytopathogenic xanthomonads in leaves of pepper (Capsicum annuum). The resistance of pepper to incompatible strains of Xanthomonas axonopodis pv. vesicatoria or to X. campestris pv. campestris is associated with increased synthesis of the hydroxycinnamoyl-tyramine conjugates, feruloyl-tyramine (FT) and coumaroyl-tyramine (CT). FT and CT are produced only in trace amounts in response to compatible strains of X. axonopodis pv. vesicatoria. Treatment of leaves with LPS from a number of bacteria did not induce the synthesis of FT and CT but altered the kinetics of induction upon subsequent bacterial inoculation. In incompatible interactions FT and CT synthesis was accelerated, whereas in compatible interactions synthesis was also considerably enhanced. The ability of the tissue to respond more rapidly was induced within 4 h of LPS treatment and the potentiated state was maintained for at least 38 h. Earlier treatment with LPS also potentiated the expression of other defense responses such as transcription of genes encoding acidic b-1,3-glucanase. Our ®ndings indicate a wider role for LPS in plant±bacterial interactions beyond its limited activity as a direct inducer of plant defenses.
Priming, induction and modulation of plant defence responses by bacterial lipopolysaccharides
Journal of Endotoxin Research, 2007
Plants in nature are involved in a variety of interactions with Gram-negative bacteria that may be of benefit or detriment to the host. In symbiotic interactions between leguminous plants and Gram-negative bacteria of the Rhizobiaceae, atmospheric nitrogen fixed by the bacteria within specialized plant-elaborated structures is made available to the host. Beneficial interactions of plants with Pseudomonas spp. in the rhizosphere (the zone of the soil directly influenced by the roots and characterized by increased microbiological activity) can lead to enhanced plant growth, increased plant disease resistance and increased resistance to environmental stresses. Conversely, pathogens belonging to the Gram-negative genera Agrobacterium, Erwinia, Pseudomonas, Ralstonia, Xanthomonas, and Xylella are responsible for some of the most serious diseases in cultivated crops. As ubiquitous and vital components of the cell surface of Gram-negative bacteria, lipopolysaccharides (LPSs) have multiple roles in these various plant-microbe interactions. LPS contributes to the reduced permeability of the Gram-negative outer membrane. This barrier function allows growth of bacteria in unfavourable conditions that
Lipopolysaccharides and plant responses to phytopathogenic bacteria
Molecular Plant Pathology, 2000
Treatment of the leaves of pepper (Capsicum annuum) cv. ECW10R with lipopolysaccharides (LPS) from both plant pathogenic and enteric bacteria alters several aspects of the plant response to subsequent inoculation with phytopathogenic xanthomonads. LPS pre-treatment prevents the hypersensitive reaction caused by strains of Xanthomonas campestris pv. vesicatoria carrying the avirulence gene avrBs1 (a gene-for-gene interaction) and by X. campestris pv. campestris (a non-host interaction). Associated with this effect are the earlier synthesis of feruloyl-and coumaroyltyramine, phenolic conjugates that are potentially antimicrobial, and alterations in the expression patterns of genes for some pathogenesis-related (PR) proteins. Similar effects on the timing of phenolic conjugate synthesis are also seen in the compatible interaction with X. campestris pv. vesicatoria , although the level of the response is lower. Recognition of LPS by plants may allow expression of resistance in the absence of catastrophic tissue damage. However phytopathogenic bacteria may have evolved mechanisms to suppress the effects of LPS (and of other non-specific bacterial elicitors) on plant cells.
Bacterial lipopolysaccharides and plant-pathogen interactions
European Journal of Plant Pathology, 2001
Lipopolysaccharides are amphipathic molecules forming the outermost layer of the cell surface of Gram-negative bacteria. They are essential for protecting the cell from hostile environments and, in the case of pathogens, they play a direct role in interactions with eukaryotic host cells. Mutants with altered lipopolysaccharide structure have been obtained with several plant pathogenic bacteria; such mutants generally show reduced virulence. Purified lipopolysaccharide has several effects on plants, notably suppression of the hypersensitive response to subsequently inoculated avirulent pathogens. The suppression is strictly localized and is observed within a time 'window' of, typically, 10-30 h. Although infiltration of lipopolysaccharide into leaves produces no macroscopic symptoms, characteristic changes in plant gene expression can be observed. One effect is to sensitize the plant tissue to subsequent bacterial inoculation so that the sensitized tissue responds more rapidly and intensely, giving partial inhibition of bacterial growth. The synthesis of antimicrobial hydroxycinnamoyl tyramine conjugates is one facet of the process which provides an excellent biochemical model for analysing the phenomenon. Lipopolysaccharide induces the synthesis of two enzymes involved in conjugate production (tyrosine decarboxylase and tyraminehydroxycinnamoyl transferase), but the conjugates themselves are not produced until bacteria are subsequently inoculated. Using this and other examples we discuss the mechanisms of lipopolysaccharide action on plants in the context of plant disease.
Journal of Plant Pathology & Microbiology, 2021
Better understanding of plant defense mechanism is crucial for improving crop health and yield. Plant defense against bacterial pathogens results from a complex combination of structural plant characteristics and induced biochemical reactions. In addition to the constitutive defense, plants may perceive directly or indirectly the presence of a bacterium and subsequently induce plant defense responses. These inducible biochemical reactions tend to create protective physiological conditions to limit bacterial growth and invasion in the host tissues. The inducible plant defense starts when a particular bacterial molecule or its structural feature is recognized by trans-membrane protein recognition receptors (PRRs) on plant cell surface. The recognition is based on conserved features of molecules of bacterial origin, namely pathogen associated molecular patterns (PAMPs). This induces PAMP-triggered immunity (PTI) and the expression of defense genes, what prevents pathogenesis. However, ...
Deciphering the dual effect of lipopolysaccharides from plant pathogenic Pectobacterium
Plant signaling & behavior, 2015
Lipopolysaccharides (LPS) are a component of the outer cell surface of almost all Gram-negative bacteria and play an essential role for bacterial growth and survival. Lipopolysaccharides represent typical microbe-associated molecular pattern (MAMP) molecules and have been reported to induce defense-related responses, including the expression of defense genes and the suppression of the hypersensitive response in plants. However, depending on their origin and the challenged plant, LPS were shown to have complex and different roles. In this study we showed that LPS from plant pathogens Pectobacterium atrosepticum and Pectobacterium carotovorum subsp. carotovorum induce common and different responses in A. thaliana cells when compared to those induced by LPS from non-phytopathogens Escherichia coli and Pseudomonas aeruginosa. Among common responses to both types of LPS are the transcription of defense genes and their ability to limit of cell death induced by Pectobacterium carotovorum s...
Plant immunity: a lesson from pathogenic bacterial effector proteins
Cellular Microbiology, 2009
Phytopathogenic bacteria inject an array of effector proteins into host cells to alter host physiology and assist the infection process. Some of these effectors can also trigger disease resistance as a result of recognition in the plant cell by cytoplasmic immune receptors. In addition to effectortriggered immunity, plants immunity can be triggered upon the detection of Pathogen/Microbe-Associated Molecular Patterns by surfacelocalized immune receptors. Recent progress indicates that many bacterial effector proteins use a variety of biochemical properties to directly attack key components of PAMP-triggered immunity and effector-triggered immunity, providing new insights into the molecular basis of plant innate immunity. Emerging evidence indicate that the evolution of disease resistance in plants is intimately linked to the mechanism by which bacterial effectors promote parasitism. This review focuses on how these studies have conceptually advanced our understanding of plant-pathogen interactions.
Induced Defense in Plants: A Short Overview
Proceedings of the National Academy of Sciences, India Section B: Biological Sciences, 2013
Phytopathogens adopt different strategies to infect and colonize the plant tissues and in turn, plants also have evolved diverse mechanisms to recognize specific signatures of the pathogens to identify the dangerous nonself ones. Pathogen recognition activates an array of defense mechanisms collectively known as induced resistance that includes the hypersensitive response (HR), in which a few plant cells at the site of infection die, limiting the spread of disease. In addition to the locally effective HR, pathogen recognition also triggers various inducible systemic defenses in plant parts distant from the site of primary infection, leading to an enhanced capacity to defend against subsequent infection. The molecular mechanism of induced plant defense is exceedingly complex and involves extensive reprogramming that bring physical, biochemical and transcriptional changes. The responses include cell wall thickening, callose deposition, production of reactive oxygen species and release of signalling compounds such as salicylic acid, jasmonic acid, ethylene and abscisic acid that perturb the infection. This review is a brief overview of the induced defense mechanisms in plants, with special reference to phytopathogenic bacteria-plant interactions.