1,720,971 research outputs found
The Arabidopsis NUCLEUS- AND PHRAGMOPLAST-LOCALIZED KINASE1-Related Protein Kinases Are Required for Elicitor-Induced Oxidative Burst and Immunity
Full text linkPlant immunity is activated through complex and cross-talking transduction pathways that include a mitogen-activated protein kinase phosphorylation cascade. Here, we have investigated the role in immunity of the Arabidopsis (Arabidopsis thaliana) gene subfamily that encodes the mitogen-activated protein triple kinases indicated as ARABIDOPSIS NUCLEUS-AND PHRAGMOPLAST-LOCALIZED KINASE1-RELATED PROTEIN KINASE1 (ANP1), ANP2, and ANP3. For this study, we used representative danger signals (elicitors) belonging to the classes of the damage-and pathogen-associated molecular patterns, i.e. oligogalacturonides, linear fragments derived from the plant cell wall homogalacturonan, and the peptide elf18 derived from the bacterial elongation factor thermo-unstable. Analyses of single and double as well as conditional triple mutants show that ANPs are required for elicitor-triggered defense responses and protection against the necrotrophic fungus Botrytis cinerea. Notably, ANPs are also required for both the elicitor-induced oxidative burst and the transduction of the hydrogen peroxide signal but not for the inhibition of auxin-induced gene expression, indicating that this response can be uncoupled from the activation of defense responses. Our findings point to ANPs as key transduction elements that coordinate damage-and pathogen-associated molecular pattern-triggered immunity and orchestrate reactive oxygen species accumulation and signaling
Camalexin Quantification in Arabidopsis thaliana Leaves Infected with Botrytis cinerea
Full text linkPhytoalexins are heterogeneous low molecular mass secondary metabolites with antimicrobial activity produced in response to pathogen invasion attempts at the infection site and represent an important part of the plant defense repertoire. Camalexin (3-Thiazol-2′-yl-indole) is a known phytoalexin first detected and isolated in Camelina sativa, from which it takes its name, infected with Alternaria brassicae (Browne et al., 1991). Production of camalexin is also induced in Arabidopsis thaliana leaves by a range of biotrophic and necrotrophic plant pathogens (bacteria, oomycetes, fungi and viruses) (Ahuja et al., 2012) as well as by abiotic stresses, such as UV and chemicals (e.g. acifluorfen, paraquat, chlorsulfuron and α-amino butyric acid) (Zhao et al., 1998; Tierens et al., 2002). Camalexin originates from tryptophan and CYP79B2 and CYP71B15 (PAD3) are P450 enzymes that catalyze important steps in its biosynthetic pathway (Glawischnig, 2007). In this protocol the detection and quantification of camalexin produced in Arabidopsis leaves infected with the necrotrophic fungus Botrytis cinerea is described
Loss of the Arabidopsis Protein Kinases ANPs Affects Root Cell Wall Composition, and Triggers the Cell Wall Damage Syndrome
Full text linkThe Arabidopsis NPK1-related Protein kinases ANP1, ANP2 and ANP3 belong to the MAP kinase kinase kinase (MAPKKK) superfamily and were previously described to be crucial for cytokinesis, elicitor-induced immunity and development. Here we investigate the basis of their role in development by using conditional β-estradiol-inducible triple mutants to overcome lethality. In seedlings, lack of ANPs causes root cell bulging, with the transition zone being the most sensitive region. We uncover a role of ANPs in the regulation of cell wall composition and suggest that developmental defects of the triple mutants, observed at the cellular level, might be a consequence of the alterations of the pectic and cellulosic cell wall components. Lack of ANPs also induced a typical cell wall damage syndrome (CWDS) similar to that observed in plants treated with the cellulose biosynthesis inhibitor isoxaben (ISX). Moreover, anp double mutants and plants overexpressing single ANPs (ANP1 or ANP3) respectively showed increased and reduced accumulation of jasmonic acid and PDF1.2 transcripts upon ISX treatment, suggesting that ANPs are part of the pathway targeted by this inhibitor and play a role in cell wall integrity surveillance.Highlights: The loss of ANP function affects cell wall composition and leads to typical cell wall damage-induced phenotypes, such as ectopic lignification and jasmonic acid accumulation
Fighting salt or enemies : shared perception and signaling strategies
No full textPlants react to a myriad of biotic and abiotic environmental signals through specific cellular mechanisms required for survival under stress. Although pathogen perception has been widely studied and characterized, salt stress perception and signaling remain largely elusive. Recent observations, obtained in the model plant Arabidopsis thaliana, show that perception of specific features of pathogens also allows plants to mount salt stress resilience pathways, highlighting the possibility that salt sensing and pathogen perception mechanisms partially overlap. We discuss these overlapping strategies and examine the emerging role of A. thaliana cell wall and plasma membrane components in activating both salt- and pathogen-induced responses, as part of exquisite mechanisms underlying perception of damage and danger. This knowledge helps understanding the complexity of plant responses to pathogens and salinity, leading to new hypotheses that could explain why plants evolved similar strategies to respond to these, at first sight, very different types of stimuli
Plant cell wall integrity maintenance in model plants and crop species-relevant cell wall components and underlying guiding principles
No full textThe walls surrounding the cells of all land-based plants provide mechanical support essential for growth and development as well as protection from adverse environmental conditions like biotic and abiotic stress. Composition and structure of plant cell walls can differ markedly between cell types, developmental stages and species. This implies that wall composition and structure are actively modified during biological processes and in response to specific functional requirements. Despite extensive research in the area, our understanding of the regulatory processes controlling active and adaptive modifications of cell wall composition and structure is still limited. One of these regulatory processes is the cell wall integrity maintenance mechanism, which monitors and maintains the functional integrity of the plant cell wall during development and interaction with environment. It is an important element in plant pathogen interaction and cell wall plasticity, which seems at least partially responsible for the limited success that targeted manipulation of cell wall metabolism has achieved so far. Here, we provide an overview of the cell wall polysaccharides forming the bulk of plant cell walls in both monocotyledonous and dicotyledonous plants and the effects their impairment can have. We summarize our current knowledge regarding the cell wall integrity maintenance mechanism and discuss that it could be responsible for several of the mutant phenotypes observed
Plant cell wall integrity maintenance in model plants and crop species-relevant cell wall components and underlying guiding principles
Full text linkThe walls surrounding the cells of all land-based plants provide mechanical support essential for growth and development as well as protection from adverse environmental conditions like biotic and abiotic stress. Composition and structure of plant cell walls can differ markedly between cell types, developmental stages and species. This implies that wall composition and structure are actively modified during biological processes and in response to specific functional requirements. Despite extensive research in the area, our understanding of the regulatory processes controlling active and adaptive modifications of cell wall composition and structure is still limited. One of these regulatory processes is the cell wall integrity maintenance mechanism, which monitors and maintains the functional integrity of the plant cell wall during development and interaction with environment. It is an important element in plant pathogen interaction and cell wall plasticity, which seems at least partially responsible for the limited success that targeted manipulation of cell wall metabolism has achieved so far. Here, we provide an overview of the cell wall polysaccharides forming the bulk of plant cell walls in both monocotyledonous and dicotyledonous plants and the effects their impairment can have. We summarize our current knowledge regarding the cell wall integrity maintenance mechanism and discuss that it could be responsible for several of the mutant phenotypes observed.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Camalexin Quantification in Arabidopsis thaliana Leaves Challenged by Botrytis cinerea
No full textPhytoalexins are heterogeneous low molecular mass secondary metabolites with antimicrobial activity produced in response to pathogen invasion attempts at the infection site and represent an important part of the plant defense repertoire. Camalexin (3-Thiazol-2′-yl-indole) is a known phytoalexin first detected and isolated in Camelina sativa, from which it takes its name, infected with Alternaria brassicae (Browne et al., 1991). Production of camalexin is also induced in Arabidopsis thaliana leaves by a range of biotrophic and necrotrophic plant pathogens (bacteria, oomycetes, fungi and viruses) (Ahuja et al., 2012) as well as by abiotic stresses, such as UV and chemicals (e.g. acifluorfen, paraquat, chlorsulfuron and α-amino butyric acid) (Zhao et al., 1998; Tierens et al., 2002). Camalexin originates from tryptophan and CYP79B2 and CYP71B15 (PAD3) are P450 enzymes that catalyze important steps in its biosynthetic pathway (Glawischnig, 2007). In this protocol the detection and quantification of camalexin produced in Arabidopsis leaves infected with the necrotrophic fungus Botrytis cinerea is described
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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