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1.
Upon infection byCladosporium fulvum, tomato plants start to produce pathogenesis-related (PR) proteins. The PR proteins 1,3-β-glucanase, chitinase, and PR-1b accumulated near the stomata in the lower epidermis ofC. fulvum-inoculated tomato leaves as could be determined by immunolocalization with polyclonal antibodies. However, no differences in accumulation of PR proteins between a compatible and an incompatible interaction were found. Results obtained from enzyme activity measurements of 1,3-β-glucanase and chitinase on similar leaf material as used for the immunolocalization did not fully reflect the immunolocalization data. The antibodies possibly detect only the extracellular but not the intracellular enzymes. The accumulation of PR proteins near the stomata might be part of a general defence response of plants against pathogens and potential pathogens.  相似文献   

2.
Tobacco becomes naturally resistant to blue mould caused by Peronospora tabacina as it ages. This age-related resistance is correlated to the time of normal floral development and the senescence of lower leaves: however, it is dependent on neither. β-1,3-Glucanase, chitinase and peroxidase activities increase in tobacco with age. These increases correlate with the development of age-related resistance to blue mould and were independent of floral development. Additionally. β-1,3-glucanase, chitinase, and peroxidase activities were higher in leaf tissue from the main stalk resistant to blue mould) as compared to leaf tissue from suckering stems (susceptible to blue mould) on the same plant. Isozyme patterns of β-1,3-glucanase and chitinase in all resistant tissues are typical of those of tissues systemically protected by either stem injection with Peronospora tabacina or foliar inoculation with TMV.  相似文献   

3.
Infection of groundnut leaves with the early leaf spot pathogen Cercospora arachidicola leads to a marked increase in extracellular 1,3-β-glucanase activity, limited to the infected tissue. Three isoforms of low molecular weight and extreme pI values, typical of pathogenesis-related proteins, were induced. These β-glucanases, when acting together, were capable of degrading the pathogen cell wall in vitro. Glucanases from homogenates of infected leaf tissue were partially purified by ion-exchange chromatography to give enzymes with molecular weights of 35, 32 and 20 kDa and pI values of 3·8, 3·6 and > 9, respectively. They were electrophoretically identical to the β-glucanases found in the intercellular washing fluid. Treatment of groundnut plants with 200 μM mercuric chloride induced the accumulation of identical extracellular β-glucanases. During the course of the infection an increase in peroxidase activity was also observed, but chitinase activity remained more or less constant.  相似文献   

4.
Tomato early blight occurs worldwide and it is prevalent wherever tomatoes are grown. Alternaria solani Sorauer, the causal agent, has been recognized as a serious foliar pathogen of tomato and there are very few cultivars which possess resistance against early blight. Alternaric acid is the major toxin of A. solani. In this study, alternaric acid and fungal culture filtrate were used as an elicitor in NDT-96 (tolerant) and GP-5 (susceptible) tomato varieties in order to study and compare their abilities to induce defense-related enzymes, viz., catalase, peroxidase, β-1,3 glucanase, phenylalanine-ammonia-lyase (PAL), chitinase and polyphenol-oxidase (PPO) along with total phenols, and total soluble proteins. NDT-96 showed a rapid induction of all these pathogenesis-related enzymes except catalase along with total phenols as compared to GP-5 with both the treatments. Differential expression of total soluble proteins revealed higher protein content in NDT-96 as compared with GP-5. A 49.48 kDa protein was observed to be absent in GP-5. In addition, 25 microsatellite markers (SSR) were screened for polymorphisms among the above mentioned two tomato varieties. Of these, SSR 286 revealed a significant polymorphic band of 108 bp in NDT-96.  相似文献   

5.
Benzothiadiazole (BTH) and DL-β-aminobutyric acid (BABA) induced systemic resistance was investigated in susceptible and resistant pea genotypes against Uromyces pisi. Resistance was characterized by reduced infection frequency mainly due to decreases in appressorium formation, stomatal penetration, growth of infection hyphae and haustorium formation. Changes in β-1,3-glucanase, chitinase, phenylalanine ammonia-lyase and peroxidase activities and in total phenolics content, demonstrate that U. pisi resistance is induced by BTH and BABA treatments at early and late stages of the fungal infection process, but that the chemicals operate via different mechanisms. In fact, our study showed that BTH treatment primed the activity of pathogenesis related-proteins such as β-1,3-glucanase, chitinase and peroxidase in both susceptible and resistant genotypes. On the other hand, BABA treatment did not increase the enzymatic activities in the studied genotypes, but significantly increased their total phenolic contents.  相似文献   

6.
ABSTRACT Infection of peanut (Arachis hypogaea) seed by Aspergillus flavus and A. parasiticus is a serious problem that can result in aflatoxin contamination in the seed. Breeding resistant cultivars would be an effective approach to reduce aflatoxin accumulation. The objective of this study was to investigate the expression of the pathogenesis-related (PR) protein beta-1,3-glucanase and the isoform patterns in peanut seed inoculated with A. flavus. Peanut genotypes GT-YY9 and GT-YY20 (both resistant to A. flavus infection) and Georgia Green and A100 (both susceptible to A. flavus infection) were used in this study. The activities of beta-1,3-glucanase were similar in the uninfected seed of all genotypes, but increased significantly in the resistant genotypes after inoculation in comparison with the susceptible genotypes. An in-gel (native polyacrylamide gel electrophoresis [PAGE]) enzymatic activity assay of beta-1,3-glucanase revealed that there were more protein bands corresponding to beta-1,3-glucanase isoforms in the infected seed of resistant genotypes than in the infected seed of susceptible genotypes. Both acidic and basic beta-1,3-glucanase isoforms were detected in the isoelectric focusing gels. Thin-layer chromatography analysis of the hydrolytic products from the reaction mixtures of the substrate with the total protein extract or individual band of native PAGE revealed the presence of enzymatic hydrolytic oligomer products. The individual bands corresponding to the bands of beta-1,3-glucanase isoforms Glu 1 to 5 were separated on the sodium dodecyl sulfate-PAGE, resulting in two bands of 10 and 13 kDa, respectively. The sequences of fragments of the 13-kDa major protein band showed a high degree of homology to conglutin, a storage protein in peanut seed. Conglutin is reported as a peanut allergen, Ara h2. Our data provide the first evidences for peanut having beta-1,3-glucanase activities and the association with the resistance to A. flavus colonization in peanut seed. We have not directly demonstrated that conglutin has beta-1,3-glucanase activity.  相似文献   

7.
Suspension-cultured rice cells showed an appreciable amount of chitinase activity when the cultured cells were treated with an elicitor isolated fromRhizoctonia solani, the rice sheath blight pathogen. A fivefold increase in chitinase activity was observed 24 h after elicitor treatment. The elicitor-inducible chitinase was purified by ammonium sulfate fractionation, chitin affinity chromatography and gel filtration. Its molecular weight is 35 kDa and it has an isoelectric point of 8.3. The 35 kDa basic chitinase inhibited mycelial growth ofR. solani in vitro. Morphological changes appeared within 1 h following exposure of mycelium to the chitinase. The hyphal tip showed marked swelling and subsequently lysis was also observed.  相似文献   

8.
Chitinases were studied in an endomycorrhiza-resistant mutant and wild type pea (Pisum sativum L. cv. Frisson) in order to characterize plant hydrolases specific to pathogenic (Aphanomyces euteiches andChalara elegans) or mycorrhizal (Glomus mosseae) root interactions. Stimulation of constitutive and induction of new chitinase activities was detected by native PAGE for acidic proteins in both pea genotypes inoculated with pathogenic fungi. In contrast, a different additional chitinase isoform was induced inG. mosseae-colonized roots. This isoform was also not elicited in chemically-stressed roots, confirming its mycorrhiza-specificity. Investigations of basic chitinase and-1,3-glucanase activities provided further evidence for differential pea responses during pathogenic and symbiotic interactions.  相似文献   

9.
Rhizoctonia solani causing rice sheath blight is responsible for significant crop yield losses. Trichoderma spp., biological control agents, have been reported to antagonize R. solani through coordinated action of several cell wall-degrading enzymes including endochitinase and β-1,3-glucanase. In this study two antifungal genes, encoding endochitinase and β-1,3-glucanase, isolated from Trichoderma sp. antagonistic to R. solani, were cloned individually in His-tagged expression vectors and mobilized in Escherichia coli for protein expression. The purified proteins assayed in vitro with R. solani impeded pathogen growth independently by causing hyphal distortions revealed through scanning electron microscopy. The combined use of endochitinase and β-1,3-glucanase did not enhance the inhibition. The distortions caused by endochitinase were due to catalytic activity of Glu172 and Asp241 residues on glycosidic linkages in chitin polymers, whereas Glu628, Tyr631, and Asp569 in β-1,3-glucanase targeted glucan polymers. The distinctions of this study from earlier reports are (a) chitin polymers in the R. solani cell wall are exposed and not embedded within the β-glucan matrix; (b) chitin and β-1,3-glucan are vital polymers in the R. solani cell wall, rather than chitin as the only main polymer; and (c) hyphal tips of R. solani remain unaffected after an antifungal assay with endochitinase and β-1,3-glucanase, instead of exhibiting distortion.  相似文献   

10.
Two antisera raised against acidic β-1,3-glucanase and acidic chitinase from tobacco were used to investigate the subcellular localization of the two enzymes in Fusarium culmorum -infected wheat spike by means of the immunogold labelling technique. The studies demonstrated that the distribution of β-1, 3-glucanase and chitinase were very similar in the uninoculated healthy and infected wheat spikes. The enzymes were localized mainly in the cell walls of different tissues including the lemma, ovary and rachis of the wheat spike, while the cytoplasm and organelles of cells in these tissues showed almost no labelling. However, the accumulation of β-1,3-glucanase and chitinase in the infected wheat spikes differed distinctly between resistant and susceptible wheat cultivars. The labelling densities for the two enzymes in the infected lemma, ovary and rachis of the susceptible cultivar Agent increased only slightly as compared to the corresponding uninoculated healthy tissues, whereas higher labelling densities of β-1,3-glucanase and chitinase were found in the infected tissues of wheat spikes from the resistant cultivar Arina compared to the corresponding uninoculated healthy tissues. Furthermore, the labelling of β-1,3-glucanase and chitinase also occurred over the cell walls of the hyphae in the infected wheat spike, but not over the hyphal cytoplasm. In addition, labelling for the two enzymes was often detected over the cell wall appositions and the electron-dense material located between the host cell and the hyphal cell in the infected tissues of the resistant wheat cultivar. The findings reported in the present study indicate that β-1,3-glucanase and chitinase accumulation in the F. culmorum -infected wheat spike may be involved in resistance to pathogen spread in the host tissue.  相似文献   

11.
Preparations of pathogenesis-related (b) proteins (PRs) from differentNicotiana species, tomato,Gynura aurantiaca, bean, and cowpea were compared to each other and to bean chitinase and a constitutive apple agglutinin by electrophoresis in polyacrylamide gels both in the absence and in the presence of SDS, and by serological double diffusion analysis using antisera against tobacco PRs and bean chitinase. PRs from different plant genera displayed a similar but not identical range of relative mobilities in both native and SDS gels, whereas bean chitinase and apple agglutinin were clearly different. None of the antisera reacted with any of the PR preparations from plant genera other than the one from which the antigen(s) had been derived. Whilst PRs within the genusNicotiana are serologically related and can be identical, PRs from different plant genera seem to be sufficiently different to be considered as genus-specific.  相似文献   

12.
Chitinase and-1,3-glucanase activities were assayed in roots, hypocotyls and cotyledons of downy mildewsusceptible and -resistant sunflower (Helianthus annuus L.) cultivars. While the highest-1,3-glucanase activity was in roots, that of chitinase activity was in hypocotyls. Inoculation of both sunflower cultivars withPlasmopara halstedii resulted in a marked increase of chitinase and-1,3-glucanase activities. The increase was observed earlier in incompatible than in compatible reactions. Both enzymes occurred in root tissue as a complex mixture of isoenzymes. At least three different peaks with chitinase activity and three with glucanase activity could be resolved by gel filtration chromatography on Sephacryl S-100 and chromatofocusing on PBE 94 (pH 7-4). Following ammonium sulfate precipitation and ion-exchange on CM- and DEAE-Trisacryl, three glucanase and chitinase fractions, referred to as basic, neutral and acidic, were separated on the basis of their Chromatographic behaviour. A different pattern of distribution of chitinase and-1,3-glucanase fractions was observed between inoculated and non-inoculated plants in both resistant (cv. RS-105) and susceptible (cv. Peredovik) cultivars. In healthy plants-1,3-glucanase was mainly found in the basic (cv. Peredovik) and neutral (cv. RS-105) fractions, whereas chitinase was in the basic fraction for both cultivars. The neutral and acidic fractions of chitinases were induced in the compatible and incompatible reactions. Inoculation of the plants induced the neutral-1,3-glucanase fraction in resistant and susceptible cultivars and the acidic only in the susceptible one. Induction of the basic fraction of both activities was not observed in any case.  相似文献   

13.
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14.
Several forms of carboxylesterase were observed in a malathion-resistant small brown planthopper, Laodelphax striatellus Fallén, by isoelectrofocusing. To study the mechanisms of increased esterase activity, esterases were purified and their biochemical characteristics were investigated in five active esterase isozymes of two resistant strains. These esterases have polymorphic characteristics and their molecular weights ranged from 66 to 70 kDa, due to variations in glycosylation. The pI values of these esterases ranged from 5.3 to 4.7. These esterases were immunologically related and NH2-terminal amino acids were identical in all isozymes regardless of pI or molecular weight. No differences have been found in kinetic parameters (Km and Vmax) to α-naphthylacetate and specific activity toward α-naphthylacetate and malathion as a substrate in all isozymes. Resistant individuals showed high ali- and malathion carboxylesterase activities and these enhancements were caused by quantitative differences of carboxylesterases with several different pI.  相似文献   

15.
 为了明确β-1,3-葡聚糖酶和几丁质酶与大豆抗疫霉根腐病的关系,测定了不同抗性大豆品种接种大豆疫霉菌后β-1,3-葡聚糖酶和几丁质酶活性的变化情况和2种酶对大豆疫霉菌的抑制作用。结果表明,大豆疫霉菌能诱导大豆β-1,3-葡聚糖酶和几丁质酶的活性增强,但2种酶在积累速度和幅度上,抗病品种和感病品种有显著的差异。与感病品种"857-1"相比,抗病品种"垦农4号"2种酶活性不仅升高的速度快、幅度大,且高活性维持的时间长。β-1,3-葡聚糖酶和几丁质酶混合液对大豆疫霉菌的菌丝生长、孢子囊形成和孢子萌发的抑制作用明显,其次是β-1,3-葡聚糖酶,而几丁质酶对大豆疫霉菌的抑制作用不明显。表明大豆对大豆疫霉根腐病的抗性与β-1,3-葡聚糖酶和几丁质酶的活性呈正相关关系。β-1,3-葡聚糖酶和几丁质酶混合对大豆疫霉菌的抑制具有协同增效作用。  相似文献   

16.
A mitogen-activated protein kinase (MAPK) pathway has been demonstrated as a key pathway in plant defense against pathogen attacks. With proteomics approaches, we specifically studied activation events downstream of a MAPK kinase, tMEK2, in tomato. Overexpression of a constitutively activated tomato MAPK kinase gene (tMEK2MUT) enhanced resistance of transgenic tomato lines to the virulent bacterial pathogen Pseudomonas syringae pv. tomato. Pathogenesis-related genes, PR1b1, β-1,3-glucanase, and endochitinase were up-regulated by tMEK2MUT. Two-dimensional electrophoresis and matrix-assisted laser desorption/ionisation-time-of-flight-mass spectrometry analysis of total soluble leaf proteins indicated that β-1,3-glucanase and endochitinase are among the up-regulated proteins in these transgenic plants. Co-expression studies using a transient gene expression system have indicated that β-1,3-glucanase and endochitinase genes up-regulated by tMEK2MUT were down-regulated by different specific phosphatases through dephosphorylation of certain downstream signaling molecules. Our observations indicate that increased products of β-1,3-glucanase and endochitinase genes downstream of tMEK2 may play an important role in achieving disease resistance.  相似文献   

17.
In this study, the biocontrol ability of seven grapevine-associated bacteria, previously reported as efficient against Botrytis cinerea under in vitro conditions, was evaluated in two vineyard orchards with the susceptible cv. Chardonnay during four consecutive years (2002–2005). It was shown that the severity of disease on grapevine leaves and berries was reduced to different levels, depending on the bacterial strain and inoculation method. Drenching the plant soil with these bacteria revealed a systemic resistance to B. cinerea, even without renewal of treatment. Accordingly, this resistance was associated with a stimulation of some plant defense responses such as chitinase and β-1,3-glucanase activities in both leaves and berries. In leaves, chitinase activity increased before veraison (end-July) while β-1,3-glucanase reached its maximum activity at ripening (September). Reverse patterns were observed in berries, with β-1,3-glucanase peaking at full veraison (end-August) and chitinase at a later development stage. Highest activities were observed with Acinetobacter lwoffii PTA-113 and Pseudomonas fluorescens PTA-CT2 in leaves, and with A. lwoffii PTA-113 and Pantoea agglomerans PTA-AF1 in berries. These results have demonstrated an induced protection of grapevine against B. cinerea by selected bacteria under field conditions, and suggest that induced resistance could be related to a stimulation of plant defense reactions in a successive manner.  相似文献   

18.
Leaves of apple (Malus domestica cv. Elstar) were infected with a cloned isolate of the apple scab Venturia inaequalis. The intercellular washing fluid (IWF) of these plants was collected and the variation in the composition of proteins in the IWF was analysed by SDS-PAGE and two-dimensional gel electrophoresis during and after the infection with V. inaequalis, the causal agent of apple scab. The subsequent analysis of induced proteins by electron spray ionization quadrupole time of flight mass spectroscopy revealed the presence of -1,3-glucanase, chitinase, thaumatin-like protein and a cysteine-like protease in M. domestica leaves infected by V. inaequalis. These results were confirmed by immunoblotting with antibodies against some of these proteins. Moreover, a non-specific lipid transfer protein was identified in uninfected leaves: the amount declined to a non-detectable level within the first week after infection by V. inaequalis. The analysis of the IWF of M. domestica cv. Remo, bearing resistances to apple scab, powdery mildew and fire blight, showed a protein pattern comparable to that of the IWF from V. inaequalis infected leaves from cultivar Elstar indicating the constitutive production at least of some of the pathogenesis-related proteins in the resistant cultivar.  相似文献   

19.
ABSTRACT In the present study, in a candidate gene approach, a class IV chitinase gene (PmCh4A) of pathogenesis-related family three was cloned and characterized in western white pine (Pinus monticola). PmCh4A chitinase expression in the different organs of healthy seedlings was below levels detectable by western immunoblot analysis using an antibody raised against PmCh4A protein. However, a 27-kDa isozyme of PmCh4A accu mulated in both susceptible and slow-canker-growth (SCG) resistant seedlings after infection by Cronartium ribicola. As with fungal infection, the application of a signal chemical (methyl jasmonate) and a protein phosphatase 1 and 2A inhibitor (okadaic acid) increased the PmCh4A protein accumulation. Furthermore, another 26-kDa isozyme was expressed specifically in SCG resistant seedlings, providing a potential tool for marker-assisted selection in forest breeding. Wounding treatment also induced expression of the protein. These data suggest that the class IV chitinase PmCh4A is involved in the defense response of western white pine to infection and abiotic stresses.  相似文献   

20.
ABSTRACT Treatment of peach fruit with UV-C light caused a rapid induction of chitinase, beta-1,3-glucanase, and phenylalanine ammonia lyase (PAL) activities starting 6 h after treatment and reaching maximum levels at 96 h after treatment. By 96 h after UV-C treatment, chitinase, beta-1,3-glucanase, and PAL activities in UV-C-treated fruit were over twofold above the levels observed for the control. In nontreated control fruit, no apparent increase in chitinase and beta-1,3-glucanase activities was detected but a minor increase in PAL activity was seen. The transient increase in chitinase, beta-1,3-glucanase, and PAL activities in UV-C-treated fruit was preceded by a gradual activation of the corresponding genes. UV-C-treated fruit showed an increase in accumulation of beta-1,3-glucanase and chitinase mRNAs at 3 h after treatment, which peaked approximately 96 h posttreatment. A similar induction kinetic pattern was observed for PAL mRNA in response to UV-C treatment, except the induction started 6 h after UV-C treatment. These results show that the response of peach fruit to elicitor treatment is similar to that seen in other plant-elicitors interactions and suggests the involvement of peach biochemical defense responses in UV-C-mediated disease resistance.  相似文献   

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