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Urs Vögeli

Bio: Urs Vögeli is an academic researcher from University of Basel. The author has contributed to research in topics: Chitinase & Chitin. The author has an hindex of 6, co-authored 6 publications receiving 1871 citations.

Papers
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Journal ArticleDOI
01 Nov 1986-Nature
TL;DR: It is reported here that the main proteinaceous inhibitor of fungal growth in bean leaves is chitinase, an enzyme that can be induced by the plant hormone ethylene, or by pathogen attack.
Abstract: The antimicrobial arsenal of plants is thought to consist mainly of secondary metabolites, among which the phytoalexins are the best-studied1–3. But plants may also possess antimicrobial proteins4,5: it has been reported that wheat-germ agglutinin, a chitin-binding lectin from wheat embryos, inhibits growth of the fungus Trichoderma viride4. This has led to the notion that plant lectins, with their intriguing biochemical similarity to animal antibodies, have an antibody-like antimicrobial function4,6,7. We report here that the main proteinaceous inhibitor of fungal growth in bean leaves is chitinase, an enzyme that can be induced by the plant hormone ethylene, or by pathogen attack. Among commercial preparations of purified chitin-binding lectins (from wheat germ, tomato, potato, pokeweed and gorse), only those containing contaminating chitinase activity inhibit fungal growth. Our data indicate that plant chitinases, but not chitin-binding lectins, are important antifungal proteins in plants.

915 citations

Journal ArticleDOI
01 Feb 1983-Planta
TL;DR: It is concluded that ethylene-induced chitinase functions as a defense enzyme against fungal and bacterial invaders.
Abstract: Ethylene induced an endochitinase in primary leaves of Phaseolus vulgaris L. The enzyme formed chitobiose and higher chitin oligosaccharides from insoluble, colloidal or regenerated chitin. Less than 5% of the total chitinolytic activity was detected in an exochitinase assay proposed by Abeles et al. (1970, Plant Physiol. 47, 129–134) for ethylene-induced chitinase. In ethylene-treated plants, chitinase activity started to increase after a lag of 6 h and was induced 30 fold within 24 h. Exogenously supplied ethylene at 1 nl ml−1 was sufficient for half-maximal induction, and enhancement of the endogenous ethylene formation also enhanced chitinase activity. Cycloheximide prevented the induction. Among various hydrolases tested, only chitinase and, to a lesser extent, β-1,3-glucanase were induced by ethylene. Induction of chitinase by ethylene occurred in many different plant species. Ethylene-induced chitinase was purified by affinity chromatography on a column of regenerated chitin. Its apparent molecular weight obtained by sodium dodecyl sulfate-gel electrophoresis was 30,000; the molecular weight determined from filtration through Sephadex G-75 was 22,000. The purified enzyme attacked chitin in isolated cell walls of Fusarium solani. It also acted as a lysozyme when incubated with Micrococcus lysodeikticus. It is concluded that ethylene-induced chitinase functions as a defense enzyme against fungal and bacterial invaders.

638 citations

01 Jan 2016
TL;DR: The localization of ethylene-induced endochitinase was studied in bean (Phaseolus vulgaris L. cv Saxa) leaves, indicating that most of the enzyme was located intracellularly.
Abstract: The localization of ethylene-induced endochitinase was studied in bean (Phaseolus vulgaris L. cv Saxa) leaves. The specific activity of chitinase in mesophyll protoplasts isolated from the leaves was as high as in tissue homogenates, indicating that most of the enzyme was located intracellularly. Vacuoles isolated and purified from the protoplasts were found to contain most of the intracellular chitinase activity.

120 citations

Journal ArticleDOI
TL;DR: In this article, the localization of ethylene-induced endochitinase was studied in bean (Phaseolus vulgaris L. cv Saxa) leaves, and it was found that most of the enzyme was located intracellularly.
Abstract: The localization of ethylene-induced endochitinase was studied in bean (Phaseolus vulgaris L. cv Saxa) leaves. The specific activity of chitinase in mesophyll protoplasts isolated from the leaves was as high as in tissue homogenates, indicating that most of the enzyme was located intracellularly. Vacuoles isolated and purified from the protoplasts were found to contain most of the intracellular chitinase activity.

115 citations

Journal ArticleDOI
01 Jun 1988-Planta
TL;DR: The results indicate that chitinase and β-1,3-glucanase are regulated co-ordinately at the level of mRNA.
Abstract: Ethylene induced chitinase (EC 3.2.1.14) and β-1,3-glucanase (EC 3.2.1.29) to a similar extent in primary leaves of bean seedlings (Phaseolus vulgaris cv. Saxa). Both enzymes were purified from ethylene-treated leaves, and monospecific antibodies were raised aginst them. Ethylene treatments strongly increased the amount of immunore-active chitinase and β-1,3-glucanase. Ethylene enhanced synthesis of chitinase in vivo, as tested by immunoprecipitation after pulse-labelling with [35S]methionine. RNA was isolated from bean leaves and translated in a rabbit reticulocyte lysate system in vitro. The chitinase and the β-1,3-glucanase antiserum each precipitated a single polypeptide from the translation products. The precipitated polypeptides were 1500 and 4000 daltons larger, respectively, than native chitinase and native β-1,3-glucanase, indicating that the two enzymes were synthesized as precursors in vitro. The translatable mRNAs for both enzymes increased at least tenfold within 2 h in response to a treatment with ethylene. When ethylene was withdrawn after 8 h of incubation, the translatable mRNAs for both enzymes decreased somewhat more slowly, reaching the basal level about 25 h later. In all cases, there was a close correlation between the levels of translatable mRNA for chitinase and β-1,3-glucanase. A putative β-1,3-glucanase cDNA clone, pCH16, was isolated by hybrid-selected translation. The amount of β-1,3-glucanase mRNA, as measured by RNA blot analysis using pCH16 as a probe, increased rapidly in response to ethylene and decreased again after withdrawal of ethylene, indicating that the amount of hybridizable RNA and of translatable mRNA for β-1,3-glucanase were correlated. In conclusion, the results indicate that chitinase and β-1,3-glucanase are regulated co-ordinately at the level of mRNA.

111 citations


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Journal ArticleDOI
TL;DR: The evolutionary conservation of similar defense-related proteins in monocots and dicots, but also their divergent occurrence in other conditions, suggest that these proteins serve essential functions in plant life, whether in defense or not.
Abstract: Inducible defense-related proteins have been described in many plant species upon infection with oomycetes, fungi, bacteria, or viruses, or insect attack. Several types of proteins are common and have been classified into 17 families of pathogenesis-related proteins (PRs). Others have so far been found to occur more specifically in some plant species. Most PRs and related proteins are induced through the action of the signaling compounds salicylic acid, jasmonic acid, or ethylene, and possess antimicrobial activities in vitro through hydrolytic activities on cell walls, contact toxicity, and perhaps an involvement in defense signaling. However, when expressed in transgenic plants, they reduce only a limited number of diseases, depending on the nature of the protein, plant species, and pathogen involved. As exemplified by the PR-1 proteins in Arabidopsis and rice, many homologous proteins belonging to the same family are regulated developmentally and may serve different functions in specific organs or tissues. Several defense-related proteins are induced during senescence, wounding or cold stress, and some possess antifreeze activity. Many defense-related proteins are present constitutively in floral tissues and a substantial number of PR-like proteins in pollen, fruits, and vegetables can provoke allergy in humans. The evolutionary conservation of similar defense-related proteins in monocots and dicots, but also their divergent occurrence in other conditions, suggest that these proteins serve essential functions in plant life, whether in defense or not.

2,747 citations

Journal ArticleDOI
TL;DR: Chitinase and β-1,3-glucanase purified from pea pods have been shown to act synergistically in the degradation of fungal cell walls.
Abstract: Chitinase and β-1,3-glucanase purified from pea pods acted synergistically in the degradation of fungal cell walls. The antifungal potential of the two enzymes was studied directly by adding protein preparations to paper discs placed on agar plates containing germinated fungal spores. Protein extracts from pea pods infected with Fusarium solani f.sp. phaseoli, which contained high activities of chitinase and β-1,3-glucanase, inhibited growth of 15 out of 18 fungi tested. Protein extracts from uninfected pea pods, which contained low activities of chitinase and β-1,3-glucanase, did not inhibit fungal growth. Purified chitinase and β-1,3-glucanase, tested individually, did not inhibit growth of most of the test fungi. Only Trichoderma viride was inhibited by chitinase alone, and only Fusarium solani f.sp. pisi was inhibited by β-1,3-glucanase alone. However, combinations of purified chitinase and β-1,3-glucanase inhibited all fungi tested as effectively as crude protein extracts containing the same enzyme activities. The pea pathogen, Fusarium solani f.sp. pisi, and the nonpathogen of peas, Fusarium solani f.sp. phaseoli, were similarly strongly inhibited by chitinase and β-1,3-glucanase, indicating that the differential pathogenicity of the two fungi is not due to differential sensitivity to the pea enzymes. Inhibition of fungal growth was caused by the lysis of the hyphal tips.

1,242 citations

Journal ArticleDOI
TL;DR: It is shown that EIN3 and EILs comprise a family of novel sequence-specific DNA-binding proteins that regulate gene expression by binding directly to a primary ethylene response element related to the tomato E4-element.
Abstract: Response to the gaseous plant hormone ethylene in Arabidopsis requires the EIN3/EIL family of nuclear proteins. The biochemical function(s) of EIN3/EIL proteins, however, has remained unknown. In this study, we show that EIN3 and EILs comprise a family of novel sequence-specific DNA-binding proteins that regulate gene expression by binding directly to a primary ethylene response element (PERE) related to the tomato E4-element. Moreover, we identified an immediate target of EIN3, ETHYLENE-RESPONSE-FACTOR1 (ERF1), which contains this element in its promoter. EIN3 is necessary and sufficient for ERF1 expression, and, like EIN3-overexpression in transgenic plants, constitutive expression of ERF1 results in the activation of a variety of ethylene response genes and phenotypes. Evidence is also provided that ERF1 acts downstream of EIN3 and all other components of the ethylene signaling pathway. The results demonstrate that the nuclear proteins EIN3 and ERF1 act sequentially in a cascade of transcriptional regulation initiated by ethylene gas.

1,205 citations

Journal ArticleDOI
TL;DR: Recent developments that support the defensive role of plant lectins are summarized and earlier work in this field is discussed against the background of the present knowledge of this group of plant proteins.
Abstract: Many plant species contain carbohydrate-binding proteins, which are commonly referred to as either lectins or agglutinins. Generally speaking, lectins are proteins that bind reversibly to specific monoor oligosaccharides. Since the initial discovery of a hemagglutinating factor in castor bean extracts by Stillmark in 1888, several hundred of these proteins have been isolated and characterized in some detail with respect to their carbohydrate-binding specificity, molecular structure, and biochemical properties. Lectins from different plant species often differ with respect to their molecular structure and specificity. It is important, therefore, to realize that all plant lectins are artificially classified together solely on the basis of their ability to recognize and bind carbohydrates. Moreover, the question arises whether proteins with a completely different structure and sugar-binding specificity fulfill the same physiological role. No conclusive answer can be given to this question as yet, for the simple reason that the role of most plant lectins is not known with certainty. There is, however, growing evidence that most lectins play a role in the plant's defense against different kinds of plant-eating organisms. The idea that lectins may be involved in plant defense is not new. In an earlier review, Chrispeels and Raikhel (1991) critically assessed the defensive role of the phytohemagglutinin family and a number of chitin-binding proteins. During the last few years important progress has been made in the study of plant lectins in general and in the understanding of their effects on other organisms in particular. In this Update we summarize the recent developments that support the defensive role of plant lectins and, in addition, discuss earlier work in this field against the background of our present knowledge of this group of plant proteins.

1,067 citations

Journal ArticleDOI
22 Nov 1991-Science
TL;DR: Transgenic tobacco seedlings constitutively expressing a bean chitinase gene under control of the cauliflower mosaic virus 35S promoter showed an increased ability to survive in soil infested with the fungal pathogen Rhizoctonia solani and delayed development of disease symptoms.
Abstract: The production of enzymes capable of degrading the cell walls of invading phytopathogenic fungi is an important component of the defense response of plants. The timing of this natural host defense mechanism was modified to produce fungal-resistant plants. Transgenic tobacco seedlings constitutively expressing a bean chitinase gene under control of the cauliflower mosaic virus 35S promoter showed an increased ability to survive in soil infested with the fungal pathogen Rhizoctonia solani and delayed development of disease symptoms.

1,025 citations