Plant signaling
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Rescooped by Arsheed Sheikh from Plant immunity and legume symbiosis
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Pathogen-secreted proteases activate a novel plant immune pathway : Nature : Nature Publishing Group

Pathogen-secreted proteases activate a novel plant immune pathway : Nature : Nature Publishing Group | Plant signaling | Scoop.it
Mitogen-activated protein kinase (MAPK) cascades play central roles in innate immune signalling networks in plants and animals1, 2. In plants, however, the molecular mechanisms of how signal perception is transduced to MAPK activation remain elusive1. Here we report that pathogen-secreted proteases activate a previously unknown signalling pathway in Arabidopsis thaliana involving the Gα, Gβ, and Gγ subunits of heterotrimeric G-protein complexes, which function upstream of an MAPK cascade. In this pathway, receptor for activated C kinase 1 (RACK1) functions as a novel scaffold that binds to the Gβ subunit as well as to all three tiers of the MAPK cascade, thereby linking upstream G-protein signalling to downstream activation of an MAPK cascade. The protease–G-protein–RACK1–MAPK cascade modules identified in these studies are distinct from previously described plant immune signalling pathways such as that elicited by bacterial flagellin, in which G proteins function downstream of or in parallel to an MAPK cascade without the involvement of the RACK1 scaffolding protein. The discovery of the new protease-mediated immune signalling pathway described here was facilitated by the use of the broad host range, opportunistic bacterial pathogen Pseudomonas aeruginosa. The ability of P. aeruginosa to infect both plants and animals makes it an excellent model to identify novel immunoregulatory strategies that account for its niche adaptation to diverse host tissues and immune systems.

Via Christophe Jacquet
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Scooped by Arsheed Sheikh
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Current Biology - The Leucine-Rich Repeat Receptor Kinase BIR2 Is a Negative Regulator of BAK1 in Plant Immunity

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Scooped by Arsheed Sheikh
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The Pseudomonas syringae effector HopF2 suppresses Arabidopsis immunity by targeting BAK1 - Zhou - 2013 - The Plant Journal - Wiley Online Library

The Pseudomonas syringae effector HopF2 suppresses Arabidopsis immunity by targeting BAK1 - Zhou - 2013 - The Plant Journal - Wiley Online Library | Plant signaling | Scoop.it
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Rescooped by Arsheed Sheikh from of Plants & Bacteria (and sometimes other fellows too)
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Variable Suites of Non-effector Genes Are Co-regulated in the Type III Secretion Virulence Regulon across the Pseudomonas syringae Phylogeny

Variable Suites of Non-effector Genes Are Co-regulated in the Type III Secretion Virulence Regulon across the Pseudomonas syringae Phylogeny | Plant signaling | Scoop.it

Scooped from: PLOS Pathogens, 2014

Authors: Tatiana S. Mucyn, Scott Yourstone, Abigail L. Lind, Surojit Biswas, Marc T. Nishimura, David A. Baltrus, Jason S. Cumbie, Jeff H. Chang, Corbin D. Jones, Jeffery L. Dangl and Sarah R. Grant.

 

Abstract:

Pseudomonas syringae is a phylogenetically diverse species of Gram-negative bacterial plant pathogens responsible for crop diseases around the world. The HrpL sigma factor drives expression of the major P. syringae virulence regulon. HrpL controls expression of the genes encoding the structural and functional components of the type III secretion system (T3SS) and the type three secreted effector proteins (T3E) that are collectively essential for virulence. HrpL also regulates expression of an under-explored suite of non-type III effector genes (non-T3E), including toxin production systems and operons not previously associated with virulence. We implemented and refined genome-wide transcriptional analysis methods using cDNA-derived high-throughput sequencing (RNA-seq) data to characterize the HrpL regulon from six isolates of P. syringae spanning the diversity of the species. Our transcriptomes, mapped onto both complete and draft genomes, significantly extend earlier studies. We confirmed HrpL-regulation for a majority of previously defined T3E genes in these six strains. We identified two new T3E families from P. syringae pv. oryzae 1_6, a strain within the relatively underexplored phylogenetic Multi-Locus Sequence Typing (MLST) group IV. The HrpL regulons varied among strains in gene number and content across both their T3E and non-T3E gene suites. Strains within MLST group II consistently express the lowest number of HrpL-regulated genes. We identified events leading to recruitment into, and loss from, the HrpL regulon. These included gene gain and loss, and loss of HrpL regulation caused by group-specific cis element mutations in otherwise conserved genes. Novel non-T3E HrpL-regulated genes include an operon that we show is required for full virulence of P. syringae pv. phaseolicola 1448A on French bean. We highlight the power of integrating genomic, transcriptomic, and phylogenetic information to drive concise functional experimentation and to derive better insight into the evolution of virulence across an evolutionarily diverse pathogen species.

 

 


Via Freddy Monteiro
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Freddy Monteiro's curator insight, January 17, 2014 7:17 AM

Congrats to Tatiana and the rest of the team for this amazing work!!