Research: Universiteit UtrechtUniversiteit Utrecht · Department of Biology · Plant-Microbe InteractionsNetherlands · Utrecht
Research: Wageningen UniversityWageningen University · Department of Phytopathology · PhytopathologyNetherlands · Wageningen
Article: Histone modifications do not play a major role in salicylate-mediated suppression of jasmonate-induced PDF1.2 gene expression.[show abstract] [hide abstract]
ABSTRACT: Cross-talk between salicylic acid (SA) and jasmonic acid (JA) defense signaling pathways allows a plant to finely tune its response to the attacker encountered. In Arabidopsis, pharmacological experiments revealed that SA exerts a strong antagonistic effect on JA-responsive genes, such as PDF1.2, indicating that the SA pathway can be prioritized over the JA pathway. We investigated the putative role of histone modifications in the regulation of SA-mediated suppression of PDF1.2 transcription. Chromatin immunoprecipitation analysis using an antibody directed against acetylated histone H3 revealed that SA does not affect the association of this histone modification at the PDF1.2 promoter, suggesting that chromatin remodeling does not play a major role in SA/JA cross-talk.Communicative & integrative biology 11/2008; 1(2):143-5.
Article: Towards a reporter system to identify regulators of cross-talk between salicylate and jasmonate signaling pathways in Arabidopsis.Annemart Koornneef, Adriaan Verhage, Antonio Leon-Reyes, Reinier Snetselaar, Lc Van Loon, Corné Mj Pieterse[show abstract] [hide abstract]
ABSTRACT: The plant signaling hormones salicylic acid (SA) and jasmonic acid (JA) are regulators of inducible defenses that are activated upon pathogen or insect attack. Cross-talk between SA- and JA-dependent signaling pathways allows a plant to finely tune its response to the attacker encountered. In Arabidopsis, pharmacological experiments revealed that SA exerts a strong antagonistic effect on JA-responsive genes, such as PDF1.2, indicating that the SA pathway can be prioritized over the JA pathway. SA-mediated suppression of the JA-responsive PDF1.2 promoter was exploited for setting up a genetic screen aiming at the isolation of signal transduction mutants that are impaired in this cross-talk mechanism. The PDF1.2 promoter was fused to the herbicide resistance gene BAR to allow for life/death screening of a population of mutagenized transgenic plants. Non-mutant plants should survive herbicide treatment when methyl jasmonate (MeJA) is applied, but suppression of the JA response by SA should be lethal in combination with the herbicide. Conversely, crucial SA/JA cross-talk mutants should survive the combination treatment. SA effectively suppressed the expression of the PDF1.2::BAR transgene. However, suppression of the BAR gene did not result in suppression of herbicide resistance. Hence, a screening method based on quantitative differences in the expression of a reporter gene may be better suited to identify SA/JA cross-talk mutants. Here, we demonstrate that the PDF1.2::GUS reporter will be excellently suited in this respect.Plant signaling & behavior 09/2008; 3(8):543-6.
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ABSTRACT: Beneficial soil-borne microorganisms, such as plant growth promoting rhizobacteria and mycorrhizal fungi, can improve plant performance by inducing systemic defense responses that confer broad-spectrum resistance to plant pathogens and even insect herbivores. Different beneficial microbe-associated molecular patterns (MAMPs) are recognized by the plant, which results in a mild, but effective activation of the plant immune responses in systemic tissues. Evidence is accumulating that systemic resistance induced by different beneficials is regulated by similar jasmonate-dependent and ethylene-dependent signaling pathways and is associated with priming for enhanced defense.Current Opinion in Plant Biology 07/2008; 11(4):443-8. · 9.27 Impact Factor
Cristina Rioja, Saskia C Van Wees, Keith A Charlton, Corné M J Pieterse, Oscar Lorenzo, Susana García-Sánchez[show abstract] [hide abstract]
ABSTRACT: Microbe-Associated Molecular Patterns and virulence effectors are recognized by plants as a first step to mount a defence response against potential pathogens. This recognition involves a large family of extracellular membrane receptors and other immune proteins located in different sub-cellular compartments. We have used phage-display technology to express and select for Arabidopsis proteins able to bind bacterial pathogens. To rapidly identify microbe-bound phage, we developed a monitoring method based on microarrays. This combined strategy allowed for a genome-wide screening of plant proteins involved in pathogen perception. Two phage libraries for high-throughput selection were constructed from cDNA of plants infected with Pseudomonas aeruginosa PA14, or from combined samples of the virulent isolate DC3000 of Pseudomonas syringae pv. tomato and its avirulent variant avrRpt2. These three pathosystems represent different degrees in the specificity of plant-microbe interactions. Libraries cover up to 2×10(7) different plant transcripts that can be displayed as functional proteins on the surface of T7 bacteriophage. A number of these were selected in a bio-panning assay for binding to Pseudomonas cells. Among the selected clones we isolated the ethylene response factor ATERF-1, which was able to bind the three bacterial strains in competition assays. ATERF-1 was rapidly exported from the nucleus upon infiltration of either alive or heat-killed Pseudomonas. Moreover, aterf-1 mutants exhibited enhanced susceptibility to infection. These findings suggest that ATERF-1 contains a microbe-recognition domain with a role in plant defence. To identify other putative pathogen-binding proteins on a genome-wide scale, the copy number of selected-vs.-total clones was compared by hybridizing phage cDNAs with Arabidopsis microarrays. Microarray analysis revealed a set of 472 candidates with significant fold change. Within this set defence-related genes, including well-known targets of bacterial effectors, are over-represented. Other genes non-previously related to defence can be associated through this study with general or strain-specific recognition of Pseudomonas.PLoS ONE 01/2013; 8(1):e54654. · 4.09 Impact Factor
Article: Low red/far-red ratios reduce Arabidopsis resistance to Botrytis cinerea and jasmonate responses via a COI1-JAZ10-dependent, salicylic acid-independent mechanism.Ignacio Cerrudo, Mercedes M Keller, Miriam D Cargnel, Patricia V Demkura, Mieke de Wit, Micaela S Patitucci, Ronald Pierik, Corné M J Pieterse, Carlos L Ballaré[show abstract] [hide abstract]
ABSTRACT: Light is an important modulator of plant immune responses. Here, we show that inactivation of the photoreceptor phytochrome B (phyB) by a low red/far-red ratio (R:FR), which is a signal of competition in plant canopies, down-regulates the expression of defense markers induced by the necrotrophic fungus Botrytis cinerea, including the genes that encode the transcription factor ETHYLENE RESPONSE FACTOR1 (ERF1) and the plant defensin PLANT DEFENSIN1.2 (PDF1.2). This effect of low R:FR correlated with a reduced sensitivity to jasmonate (JA), thus resembling the antagonistic effects of salicylic acid (SA) on JA responses. Low R:FR failed to depress PDF1.2 mRNA levels in a transgenic line in which PDF1.2 transcription was up-regulated by constitutive expression of ERF1 in a coronatine insensitive1 (coi1) mutant background (35S::ERF1/coi1). These results suggest that the low R:FR effect, in contrast to the SA effect, requires a functional SCFCOI1-JASMONATE ZIM-DOMAIN (JAZ) JA receptor module. Furthermore, the effect of low R:FR depressing the JA response was conserved in mutants impaired in SA signaling (sid2-1 and npr1-1). Plant exposure to low R:FR ratios and the phyB mutation markedly increased plant susceptibility to B. cinerea; the effect of low R:FR was (1) independent of the activation of the shade-avoidance syndrome, (2) conserved in the sid2-1 and npr1-1 mutants, and (3) absent in two RNA interference lines disrupted for the expression of the JAZ10 gene. Collectively, our results suggest that low R:FR ratios depress Arabidopsis (Arabidopsis thaliana) immune responses against necrotrophic microorganisms via a SA-independent mechanism that requires the JAZ10 transcriptional repressor and that this effect may increase plant susceptibility to fungal infection in dense canopies.Plant physiology 02/2012; 158(4):2042-52. · 6.53 Impact Factor