Membrane Trafficking in Plant Immunity

Gu, Yangnan; Zavaliev, Raul; Dong, Xinnian

doi:10.1016/j.molp.2017.07.001

Cited by 117 publications

(105 citation statements)

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“…Specific conditions, such as active growth and infection, engage the secretory pathway and significantly enhance its activity (Wang et al, 2005). During the immune response de-novo synthesis of a vast array of proteins is induced, including PM-localized receptors and proteins with antimicrobial activities which are delivered to the extracellular space (Gu et al, 2017). The defence hormone salicylic acid (SA) plays a key function by coordinately upregulating the secretory pathway (Wang et al, 2005; Nagashima et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function

Ditengou

et al. 2018

Preprint

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The exocyst is a conserved hetero-octameric complex that mediates early tethering of post-Golgi vesicles during exocytosis. Its Exo70 subunit functions as a spatiotemporal regulator by mediating numerous interactions with proteins and lipids. However, a molecular understanding of the exocyst functions remains challenging. Exo70B2 localized to dynamic foci at the plasma membrane and transited through Brefeldin A (BFA)-sensitive compartments, indicating that it participates in conventional secretion. Conversely, treatment with the immunogenic peptide flg22 or the salicylic acid (SA) defence hormone analogue Benzothiadiazole (BTH), induced Exo70B2 transport into the vacuole where it colocalized with autophagic markers AUTOPHAGY-RELATED PROTEIN 8 (ATG8) and NEIGHBOR OF BRCA1 GENE 1 (NBR1). According with its role in immunity, we discovered that Exo70B2 interacts with and is phosphorylated by the MITOGEN-ACTIVATED PROTEIN KINASE 3 (MPK3). Mimicking phosphorylation inhibited Exo70B2 localization at sites of active secretion. By contrast, lines expressing phosphonull variants displayed higher Effector-Triggered Immunity and were hypersensitive to BTH, conditions known to induce the secretory pathway. Our results suggest a molecular mechanism by which phosphorylation of Exo70B2 regulates interaction with the plasma membrane, and couples the secretory pathway with cellular signalling.

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Section: Introductionmentioning

confidence: 99%

Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function

Ditengou

et al. 2018

Preprint

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“…Membrane trafficking plays an important role in plant-pathogen interactions and mutants with lesions in several different plant vesicular trafficking genes exhibiting compromised responses to bacterial or fungal pathogens in the model plant species A. thaliana have been identified in previous studies (Gu et al, 2017; Yun and Kwon, 2017; Ekanayake et al, 2019). Moreover, it appears that some pathogens evolved host cell translocated effector proteins that promote disease by interfering with plant membrane trafficking pathways (Ben Khaled et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Whereas other molecules are trafficked from the vacuole and other cellular compartments to the apoplast and to the cell wall to orchestrate cytoplasm communication during immune signal transduction. This has been well documented, with A. thaliana and its vast available genetic resources being particularly well exploited for functional studies of vesicular trafficking components and pathways (Ben Khaled et al, 2015; Gu et al, 2017; Yun and Kwon, 2017; Ekanayake et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

The vesicular trafficking system component MIN7 is required for minimizingFusarium graminearuminfection

Wood

Panwar

Grimwade-Mann

et al. 2020

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Plants have developed intricate defense mechanisms, referred to as innate immunity, to defend themselves against a wide range of pathogens. Plants often respond rapidly to pathogen attack by the synthesis and delivery of various antimicrobial compounds, proteins and small RNA in membrane vesicles to the primary infection sites. Much of the evidence regarding the importance of vesicular trafficking in plant-pathogen interactions comes from the studies involving model plants whereas this process is relatively understudied in crop plants. Here we assessed whether the vesicular trafficking system components previously implicated in immunity in Arabidopsis thaliana play a role in the interaction with Fusarium graminearum, a fungal pathogen notoriously famous for its ability to cause Fusarium head blight (FHB) disease in wheat. Among the analyzed vesicular trafficking mutants, two independent T-DNA insertion mutants in the AtMin7 gene displayed a markedly enhanced susceptibility to F. graminearum. Earlier studies identified this gene, encoding an ARF-GEF protein, as a target for the HopM1 effector of the bacterial pathogen Pseudomonas syringae pv. tomato, which destabilizes AtMIN7 leading to its degradation and weakening host defenses. To test whether this key vesicular trafficking component may also contribute to defense in crop plants, we identified the candidate TaMin7 genes in wheat and knocked-down their expression through Virus induced gene silencing. Wheat plants in which TaMIN7 were silenced displayed significantly more FHB disease. This suggests that disruption of MIN7 function in both model and crop plants compromises the trafficking of innate immunity signals or products resulting in hyper-susceptibility to various pathogens.One sentence summaryDisruption of an ARF-GEF protein encoding gene AtMin7 in Arabidopsis thaliana and silencing of the orthologous gene in wheat result in hyper susceptibility to the fungal pathogen Fusarium graminearum.

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“…Plants are exposed to diverse pathogens and rely on both passive and active defenses in order to restrict infection. Passive plant defenses include a waxy cuticle, pre-formed antimicrobial compounds, and the cell wall (Gu et al, 2017). Inducible defenses are often triggered by membrane-localized pattern recognition receptors (PRRs) as well as intracellular nucleotide-binding site leucine-rich repeat proteins (NLRs) (Boutrot and Zipfel, 2017; Lolle et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Identification of a plant kinase that phosphorylates the bacterial effector AvrPtoB

Coaker

2020

Preprint

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9A critical component controlling bacterial virulence is the delivery of pathogen effectors into 10 plant cells during infection. Effectors alter host metabolism and immunity for pathogen benefit. 11 Multiple effectors are phosphorylated by host kinases, and this posttranslational modification is 12 important for their activity. We sought to identify host kinases involved in effector 13 phosphorylation. Multiple effector phosphorylated residues matched the proposed consensus 14 phosphorylation motif of the plant calcium-dependent protein kinase (CDPK) and Snf1-related 15 kinase (SnRK) superfamily. The conserved Pseudomonas effector AvrPtoB acts as an E3 16 ubiquitin ligase and promotes bacterial virulence. We identified a member of the Arabidopsis 17 SnRK family, SnRK2.8, that associated with AvrPtoB in yeast and in planta. SnRK2.8 was 18 required for AvrPtoB virulence functions, including facilitating bacterial colonization, 19 suppression of callose deposition, and targeting the plant defense regulator NPR1 and flagellin 20 receptor FLS2. Mass spectrometry revealed AvrPtoB was phosphorylated at multiple serine 21 residues in planta, with S258 phosphorylation reduced in the snrk2.8 knockout. AvrPtoB 22 phospho-null mutants exhibited compromised virulence functions and were unable to suppress 23 NPR1 accumulation, FLS2 accumulation, or inhibit FLS2-BAK1 complex formation upon 24 flagellin perception. These data identify a conserved plant kinase utilized by a pathogen effector 25 to promote disease.26 27 Plants are exposed to diverse pathogens and rely on both passive and active defenses in order to 29 restrict infection. Passive plant defenses include a waxy cuticle, pre-formed antimicrobial 30 compounds, and the cell wall (Gu et al., 2017). Inducible defenses are often triggered by 31 membrane-localized pattern recognition receptors (PRRs) as well as intracellular nucleotide-32 binding site leucine-rich repeat proteins (NLRs) (Boutrot and Zipfel, 2017; Lolle et al., 2020). 33 Common plant immune responses after active pathogen perception include the production of 34 reactive oxygen species (ROS), callose deposition, activation of mitogen-activated protein 35 kinases, and global transcriptional reprogramming towards defense (Bigeard et al., 2015; Peng et 36 al., 2018). 37 To colonize their hosts, pathogens rely on the ability to secrete effector proteins. Characterized 38 effectors act to suppress plant immune responses, alter host developmental processes, and affect 39 host metabolism to promote pathogen infection (Toruño et al., 2015). Bacterial pathogens have 40 the most well-characterized effector repertoires. For example, the Pseudomonas syringae 41 effectors AvrPto and HopAO1 directly interact with the cytoplasmic domains of the PRRs 42 FLAGELLIN-SENSING 2 (FLS2) and ELONGATION FACTOR-Tu RECEPTOR (EFR), and 43 inhibit PRR kinase activity (Xiang et al., 2008; Macho et al., 2014). Effectors are also capable of 44 manipulating plant hormone processes. The P. syringae effector HopX1 and its Ralstonia 45 solanac...

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Membrane Trafficking in Plant Immunity

Cited by 117 publications

References 104 publications

Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function

Phosphorylation of the exocyst subunit Exo70B2 contributes to the regulation of its function

The vesicular trafficking system component MIN7 is required for minimizingFusarium graminearuminfection

Identification of a plant kinase that phosphorylates the bacterial effector AvrPtoB

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