Topic
Phytoalexin
About: Phytoalexin is a research topic. Over the lifetime, 1161 publications have been published within this topic receiving 63405 citations. The topic is also known as: phytoalexins.
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TL;DR: The postulate that phytoalexin production is confined to cells undergoing necrobiosis remains in doubt because of the absence of techniques for the accurate localisation of the inhibitors within infected tissues.
Abstract: STUDIES on the role of phytoalexins in disease resistance in plants have been limited by the absence of techniques for the accurate localisation of the inhibitors within infected tissues. As a result the postulate of Muller and Borger1 that phytoalexin production is confined to cells undergoing necrobiosis remains in doubt2.
69 citations
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TL;DR: The analysis of the cis-acting sequences involved in the regulation of chalcone synthase has been facilitated by the use of electroporated protoplasts as a transient assay system and theUse of DNA footprinting and gel-retardation assays will help identify the corresponding trans-acting factors involved inThe regulation of these genes.
Abstract: . Plants respond actively to infection and other environmental stresses by synthesizing phytoalexins and defence-related proteins. This response can be induced in plant cell suspension cultures with compounds known as elicitors. These are often carbohydrates of fungal origin. In bean, transcriptional activation of the defence genes commences less than five minutes after elicitor addition, thus it is clearly a very rapid response implying few biochemical steps exist between elicitor interaction and the initiation of defence gene transcription. The induction of phytoalexin biosynthesis during incompatible interactions of bean with Colletotrichum lindemuthianum occurs rapidly during the initial contact between the host and pathogen. This appears to be a direct response to molecular recognition of the pathogen. In compatible interactions however, the pathogen grows biotrophically and phytoalexin biosynthesis is not triggered until lesions begin to form. Thus this may be a response to tissue damage rather than direct molecular recognition. Many bean defence genes, including those regulating key points in the phytoalexin biosynthetic pathway, exist in the genome as small multigene families. In some cases there is differential regulation within a family in response to developmental and environmental signals. The analysis of the cis-acting sequences involved in the regulation of chalcone synthase has been facilitated by the use of electroporated protoplasts as a transient assay system. This work and the use of DNA footprinting and gel-retardation assays will help identify the corresponding trans-acting factors involved in the regulation of these genes. While progress is being made in understanding the mechanisms of transcriptional activation of defence genes little is known of how plants recognize pathogens and elicitors or how this signal is transduced to the nucleus.
69 citations
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TL;DR: Studies of plant-microorganism interactions yielded the first evidence that oligosaccharides could serve as biological signals, and this research focused on the synthesis and accumulation of antimicrobial phytoalexins in response to microbial attack.
Abstract: Studies of plant-microorganism interactions yielded the first evidence that oligosaccharides could serve as biological signals Much of this research focused on the synthesis and accumulation of antimicrobial phytoalexins in response to microbial attack Phytoalexin synthesis and accumulation are observed not only after microbial infection, but also after treatment of plant tissue with cell-free extracts of microbial origin
69 citations
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TL;DR: Results suggest that the two signalling pathways have a pivotal role in regulating a cellular compensatory response to preserve cell integrity during exposure to camalexin and that outputs of activated cascades contribute to protecting the fungus against antimicrobial plant metabolites.
Abstract: Camalexin, the characteristic phytoalexin of Arabidopsis thaliana, inhibits growth of the fungal necrotroph Alternaria brassicicola. This plant metabolite probably exerts its antifungal toxicity by causing cell membrane damage. Here we observed that activation of a cellular response to this damage requires cell wall integrity (CWI) and the high osmolarity glycerol (HOG) pathways. Camalexin was found to activate both AbHog1 and AbSlt2 MAP kinases, and activation of the latter was abrogated in a AbHog1 deficient strain. Mutant strains lacking functional MAP kinases showed hypersensitivity to camalexin and brassinin, a structurally related phytoalexin produced by several cultivated Brassica species. Enhanced susceptibility to the membrane permeabilization activity of camalexin was observed for MAP kinase deficient mutants. These results suggest that the two signalling pathways have a pivotal role in regulating a cellular compensatory response to preserve cell integrity during exposure to camalexin. AbHog1 and AbSlt2 deficient mutants had reduced virulence on host plants that may, at least for the latter mutants, partially result from their inability to cope with defence metabolites such as indolic phytoalexins. This constitutes the first evidence that a phytoalexin activates fungal MAP kinases and that outputs of activated cascades contribute to protecting the fungus against antimicrobial plant metabolites.
68 citations
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TL;DR: Two differentially ozone-sensitive cell lines obtained from Vitis vinifera leaf explants, one richer in polyphenols and brown pigmented (Ph+) and the other phenol-poorer and pale (Ph−), were used as experimental tool for analyzing ozone (O 3 ) stress response.
68 citations