1,721,006 research outputs found
Gene expression analyses reveal a relationship between conidiation and cerato-platanin in homokaryotic and heterokaryotic strains of the fungal plant pathogen Heterobasidion irregulare
Full text linkThe Basidiomycete Heterobasidion irregulare was recently sequenced and three cerato-platanin encoding genes were found in its genome (HiCPs). Cerato-platanin family proteins (CPPs) are produced by both plant pathogenic and non-pathogenic fungi, and can act both as virulence factors and elicitors of defence responses. In fungal life these proteins seem to play a dual role, in the fungal cell wall and in the fungus-plant interaction, but most data available to date on CPPs derive from studies performed on Ascomycetes. In the present study, we investigated the expression of HiCPs in three homokaryotic isolates and two heterokaryotic isolates of the forest pathogen H. irregulare. Transcription of HiCPs was analysed both at the edge and at the centre of the fungal colony and compared between homokaryon and heterokaryon. Results showed that only HiCP1 and HiCP2 are likely to be translated in H. irregulare and that, under the tested conditions, HiCP1 is by far the gene with the highest transcript abundance among HiCPs. HiCP1 did not show any preferential expression in different sections of the fungal colony, while HiCP2 was significantly more expressed at the colony centre, thus suggesting a link with the production of conidia. The level of expression of HiCPs in heterokaryons was generally comparable to that of one or both the parental homokaryons, irrespective of the colony section, thus demonstrating that HiCPs are not transcriptionally influenced by the heterokaryotic stage
Approfondimenti: I meccanismi alla base dell’ISR e del defense priming
No full textIl testo di Patologia Vegetale Molecolare, scritto da più di 70 autori e coordinato da Massimo Reverberi, Lorenzo Covarelli, Michelina Ruocco e Luca Sella, rappresenta un affresco
attuale delle conoscenze sull’interazione pianta-patogeno, sulla biologia dei principali patogeni vegetali, sugli approcci sostenibili alla lotta contro le fitopatie, fino agli aspetti diagnostici molecolari più innovativi
Transcriptional study of cerato-platanin encoding genes in homokaryotic and heterokaryotic isolates of the forest pathogen Heterobasidion irregulare.
Full text linkThe forest pathogen Heterobasidion irregulare (Basidiomycota) was recently sequenced and three cerato-platanin encoding genes were found in its genome (HiCPs). Cerato-Platanin Proteins (CPPs) are a family of proteins well known for they resistance-inducing ability when applied on plants. What is still poorly understood is their role in fungal life. These proteins seem to play both a role in the fungal cell wall and a role in the fungus-plant interaction, but most data available to date on CPPs derive from studies performed on Ascomycetes. In the present study, we investigated the expression of HiCPs in three homokaryotic isolates and two heterokaryotic isolates of the plant pathogen H. irregulare. Homokaryotic and heterokaryotic mycelia not only play different roles in the infectious process but also differ in their biology: clamp connections are formed in the heterokaryotic mycelia. Transcription of HiCPs was analysed both at the edge and at the centre of the fungal colony and compared between homokaryon and heterokaryon. Results showed HiCP1 to be the gene with the highest transcript abundance among HiCPs. HiCP1 did not show any preferential expression in different sections of the fungal colony, while HiCP2 was significantly more expressed at the colony centre, thus suggesting a link with the production of conidia. The level of expression of HiCPs in heterokaryons was generally comparable to that of one or both the parental homokaryons, irrespective of the colony section, thus demonstrating that HiCPs are not transcriptionally influenced by the heterokaryotic stage
Early transcription of defence-related genes in Platanus acerifolia leaves after treatment with cerato-platanin and cerato-populin
No full textCerato-platanin (CP) and cerato-populin (Pop1) are small non-catalytic proteins produced by the ascomycetes Ceratocystis platani and C. populicola. C. platani is responsible for the canker stain disease of plane trees, and C. populicola for the black canker of poplar trees. CP and Pop1 are PAMPs (pathogen-associated molecular patterns) inducing typical defense responses in various host and non-host plants. CP causes the up-regulation of defence-related genes in Platanus acerifolia leaves treated for 48 hours. However, other defence-related events like cell plasmolysis and localized resistance occur before 48 hours. With the present work, the transcriptional changes caused by CP in P. acerifolia leaves were studied during the first 24 hours. A cDNA microarray containing both P. acerifolia transcripts induced by CP after 48 hours (Baccelli et al. 2008, Fontana et al. 2008) and poplar transcripts induced by cold or ozone (Rizzo et al. 2007, Maestrini et al. 2009) was designed to study the gene regulation induced by CP at 24 hours. Out of 318 cDNA sequences present on the microarray, 131 turned out to be differentially regulated in P. acerifolia leaves after 24 hours of treatment with CP. Out of the 131 modulated transcripts, 86 new sequences of P. acerifolia differentially regulated by CP, 35 up-regulated and 51 down-regulated, were found; these new CP-responsive genes were grouped in seven functional categories. Interestingly, the microarray contained 100 P. acerifolia transcripts known to be up-regulated by CP after 48 hours of treatment, but only 36 were also up-regulated after 24 hours. In order to confirm the microarray analysis, quantitative PCRs (qPCRs) were performed on five selected transcripts. Although with some differences, qPCR data validated the microarray results. The transcripts used to validate the microarray result were also selected to carry out a time-course analysis in P. acerifolia leaves treated with CP also comparing the eliciting activity of CP with Pop1. CP and Pop1 were able to induce early transcriptional changes, confirming that PAMPs act at gene transcription level very quickly after their perception
The priming fingerprint on the plant transcriptome investigated through meta-analysis of RNA-Seq data
No full textPlants may enter into a state of alert that allows them to deploy defensive measures in a more effective way upon stress occurrence. This phenomenon is termed defense priming, and it is started in plants with a still enigmatic priming phase in which complex molecular and physiological changes occur. During the priming phase the plant transcriptome is deeply affected, but it remains largely unclear the extent of the transcriptional changes that contribute to prime the plant. In this study, we performed a meta-analysis of publicly available RNA-Seq data obtained during different priming conditions and in different plant species in order to investigate the existence of a transcriptional “priming fingerprint”. Our results show that similarities in transcriptome reprogramming affect a small group of genes with similar and often low fold change value. Similarities affect, among others, the down-regulation of genes involved in methylerythritol 4-phosphate (MEP) pathway (e.g. DXR), photosynthesis (e.g. PSBQ-2), fatty acid synthesis (e.g. FAD2), and transcription factors (TFs) enabling normal development (e.g. BES1, DAR2, COL9), likely reflecting eventual metabolic costs. In contrast, the up-regulation of genes encoding receptors (e.g. RPM1), MAP kinases (MKK2, MPK6, MPK1), TFs enabling defense (e.g. RAP2.12, EIN3, WRKY18, HSFA4A, HSF3, BZIP17), genes involved in beta-oxidation (ACX1), monoterpene synthesis (GPS1), and negative immune signaling regulators (e.g. PP2C38 and BIR1) highlight a common preparation for a broad-spectrum defense. This study reveals a set of conserved transcriptional changes that mark the priming phase in plants, and aids to decipher the role of the transcriptome within the priming changes
Induzione di resistenza e defense priming.
No full textIl testo di Patologia Vegetale Molecolare, scritto da più di 70 autori e coordinato da Massimo Reverberi, Lorenzo Covarelli, Michelina Ruocco e Luca Sella, rappresenta un affresco
attuale delle conoscenze sull’interazione pianta-patogeno, sulla biologia dei principali patogeni vegetali, sugli approcci sostenibili alla lotta contro le fitopatie, fino agli aspetti diagnostici molecolari più innovativi
Twenty years of research on cerato-platanin family proteins: clues, conclusions, and unsolved issues
No full textTwenty years of research on cerato-platanin family proteins (CPPs) have led to some clear conclusions: CPPs are exclusively present in the fungal kingdom and possess an outstanding capacity to stimulate the immune system of plants. Recent discoveries have highlighted remarkable structural and functional similarities between CPPs and expansins, a class of non-enzymatic proteins found in both plants and microbes possessing loosening ability on the cell wall structure. Nevertheless, the determination of a biological role for CPPs in fungi is becoming a complicated puzzle to solve, since experimental data are often divergent and point to functional diversification. A general consensus appears however possible: CPPs from pathogenic and beneficial fungi may be considered as microbe-associated molecular patterns (MAMPs) and likely play a dual role, exerting functions in the fungal cell wall and/or in plant colonization. In this review, which celebrates 20 y of research on CPPs, we trace the history of these proteins and highlight experimental evidence and still unsolved issues
Cerato-platanin shows expansin-like activity on cellulosic materials.
No full textCerato-platanin (CP) is a protein elicitor produced by Ceratocystis platani, the causal agent of canker stain of plane tree. The eliciting activity of CP has been extensively studied, and in accordance with the “zig-zag model” described by Jones and Dangl (2006), CP may be considered a PAMP (pathogen-associated molecular pattern). However, the primary role of CP and of all the
other proteins of the “cerato-platanin family” in fungi is unknown. CP is both a structural component of the cell wall of C. platani and a protein secreted in the medium where the fungus
grows. No lytic activity has ever been reported. Recently, by studying the three-dimensional structure of the protein and the pattern of gene expression, a clue on its role has been found: CP
could act in the remodelling and enlargement of the cell wall during hyphal growth and in the formation of chlamydospores, with a role like that of expansins. In the present work, the expansinlike activity of CP was investigated. Like expansins, CP was able to disrupt filter paper in a concentration-dependent manner and to cause fragmentation of the crystalline cellulose Avicel. Cotton fibers incubated for 24 h with CP, then sonicated, showed breakage and defibration, whereas fibers incubated in buffer alone remained undamaged. Optimum of pH and temperature for CP activity were determined. Results strongly suggest that CP may be a new fungal expansin. Its possible synergistic effect with cellulases is under investigation
Cerato-platanin shows expansin-like activity on cellulosic materials
No full textCerato-platanin (CP) is a non-catalytic protein with a double ψβ-barrel fold located in the cell wall of the phytopathogenic fungus Ceratocystis platani. CP is released during growth and induces defence-related responses in plants. CP is also the first member of the "cerato-platanin family" (CPF) (Pfam PF07249). In the CPF, the molecular mechanism of action on plants and above all the biological role in fungal life are little-known aspects. However, an expansin-like function has recently been suggested concerning CP. Expansin-like proteins have the ability to act non-hydrolytically on cellulose. In the present work, the expansin-like activity of CP and Pop1, a CP family member, was investigated. Like expansins, CP and Pop1 were able to weaken filter paper in a concentration-dependent manner and without the production of reducing sugars. A metal-dependent polysaccharide monooxygenase-like activity was excluded. The optimum of activity was pH 5.0, 38 °C. CP was also able to cause fragmentation of the crystalline cellulose Avicel and the breakage and defibration of cotton fibres. However, the interaction did not involve a stable bond with the substrates and CP did not significantly enhance the hydrolytic activity of cellulase. On the other hand, CP and Pop1 bound quickly to chitin. We consider CP as a novel one-domain expansin-like protein. We propose a structural role for CP in the fungal cell wall due to the ability to bind chitin, and hypothesize a functional role in the interaction of the fungus with the plant for the weakening activity shown on cellulose
Early transcription of defence-related genes in Platanus acerifolia leaves following treatment with cerato-platanin
No full textThe protein elicitor cerato-platanin (CP) is known to induce defence-related responses in various plants. Some of these responses occur very quickly. In the present work, the transcriptional changes caused by CP in leaves from Platanus acerifolia were studied during the first 24 hours.
With a cDNA microarray 131 differentially regulated transcripts were identified as responsive to CP after 24 hours of treatment. Eighty-six of these were cold- or ozone-modulated transcripts from poplar, thus revealing a significant overlap between genes responsive to CP and to cold/ozone stress. The transcriptional changes caused by CP were compared with Pop1, a CP-orthologous protein, in a time-course analysis performed after 3, 6, 12 and 24 hours by real-time RT-PCR on five defence-related genes. CP and Pop1 were able to induce early transcriptional changes (WRKY was overexpressed after only 3 hours), although the two proteins acted differently on gene transcription
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