Phosphatidylcholines from Pieris brassicae eggs activate an immune response in Arabidopsis

Recognition of conserved microbial molecules activates immune responses in plants, a process termed pattern-triggered immunity (PTI). Similarly, insect eggs trigger defenses that impede egg development or attract predators, but information on the nature of egg-associated elicitors is scarce. We performed an unbiased bioactivity-guided fractionation of eggs of the butterfly Pieris brassicae. Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry of active fractions led to the identification of phosphatidylcholines (PCs). PCs are released from insect eggs, and they induce salicylic acid and H2O2 accumulation, defense gene expression and cell death in Arabidopsis, all of which constitute a hallmark of PTI. Active PCs contain primarily C16 to C18-fatty acyl chains with various levels of desaturation, suggesting a relatively broad ligand specificity of cell-surface receptor(s). The finding of PCs as egg-associated molecular patterns (EAMPs) illustrates the acute ability of plants to detect conserved immunogenic patterns from their enemies, even from seemingly passive structures such as eggs.

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Sphingolipids are involved in Pieris brassicae egg-induced cell death in Arabidopsis thaliana

10.1101/2021.07.09.451813 ◽

2021 ◽

Author(s):

Raphaël Groux ◽

Laetitia Fouillen ◽

Sébastien Mongrand ◽

Philippe Reymond

Keyword(s):

Cell Death ◽

Pieris Brassicae ◽

Fatty Acyl ◽

Sphingolipid Metabolism ◽

Central Component ◽

Oxygen Species ◽

Ceramide Synthase ◽

Large White ◽

Egg Extract ◽

Acyl Chains

In Brassicaceae, hypersensitive-like (HR-like) cell death is a central component of direct defenses triggered against eggs of the large white butterfly Pieris brassicae. The signaling pathway leading to HR-like in Arabidopsis is mainly dependent on salicylic acid (SA) accumulation, but downstream components are unclear. Here, we found that treatment with P. brassicae egg extract (EE) trigger changes in expression of sphingolipid metabolism genes in Arabidopsis and Brassica nigra. Disruption of ceramide synthase activity led to a significant decrease of EE-induced HR-like whereas SA signaling and reactive oxygen species levels were unchanged, suggesting that ceramides are downstream activators of HR-like. Sphingolipid quantifications showed that ceramides with C16-0 side-chains accumulated in both species, and this response was independent on SA accumulation. Finally, we provide genetic evidence that the modification of fatty acyl chains of sphingolipids modulates HR-like. Altogether, these results show that sphingolipids play a key and specific role during insect egg-triggered HR-like.

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Cellular distribution, regulation, and biochemical nature of an Fc alpha receptor in humans.

Journal of Experimental Medicine ◽

10.1084/jem.171.3.597 ◽

1990 ◽

Vol 171 (3) ◽

pp. 597-613 ◽

Cited By ~ 138

Author(s):

R C Monteiro ◽

H Kubagawa ◽

M D Cooper

Keyword(s):

Cell Lines ◽

Receptor Expression ◽

Cell Surface Receptor ◽

Ligand Specificity ◽

Transmembrane Glycoprotein ◽

Human Granulocytes ◽

Surface Receptor ◽

Igg Receptors ◽

Monocyte Cell ◽

Distinctive Role

In these studies, we characterize an Fc receptor (FcR) for IgA that is present on human granulocytes, monocyte/macrophages, and their corresponding cell lines. Receptor expression appears to be constitutive but can be selectively upregulated on monocyte cell lines by stimulation with a phorbol ester and polymeric IgA. Both the induction requirements and ligand specificity of the IgA receptor differ from the IgG receptors, Fc gamma R I, II, and III, that are also expressed on monocytes and granulocytes. IgA binding to the cell surface receptor is mediated via the Fc alpha region. The Fc alpha R is a heterogenously charged, approximately 60-kD molecule with an isoelectric point of 4.5-5.6 that binds monomeric or polymeric IgA1 and IgA2 molecules. This transmembrane glycoprotein appears to be composed of 32- and 36-kD protein cores with multiple N-linked carbohydrate moieties. We conclude that this Fc alpha R represents a novel member of the FcR family that may have a distinctive role in host defense.

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The Immunity Regulator BAK1 Contributes to Resistance Against Diverse RNA Viruses

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-06-13-0179-r ◽

2013 ◽

Vol 26 (11) ◽

pp. 1271-1280 ◽

Cited By ~ 74

Author(s):

Camilla Julie Kørner ◽

Dominik Klauser ◽

Annette Niehl ◽

Ana Domínguez-Ferreras ◽

Delphine Chinchilla ◽

...

Keyword(s):

Rna Viruses ◽

Transcriptional Gene Silencing ◽

Dependent Manner ◽

Antiviral Defense ◽

Defense Gene Expression ◽

Defense Gene ◽

Resistance Proteins ◽

Post Transcriptional Gene Silencing ◽

Effector Triggered Immunity ◽

Molecular Patterns

The plant's innate immune system detects potential biotic threats through recognition of microbe-associated molecular patterns (MAMPs) or danger-associated molecular patterns (DAMPs) by pattern recognition receptors (PRR). A central regulator of pattern-triggered immunity (PTI) is the BRI1-associated kinase 1 (BAK1), which undergoes complex formation with PRR upon ligand binding. Although viral patterns inducing PTI are well known from animal systems, nothing similar has been reported for plants. Rather, antiviral defense in plants is thought to be mediated by post-transcriptional gene silencing of viral RNA or through effector-triggered immunity, i.e., recognition of virus-specific effectors by resistance proteins. Nevertheless, infection by compatible viruses can also lead to the induction of defense gene expression, indicating that plants may also recognize viruses through PTI. Here, we show that PTI, or at least the presence of the regulator BAK1, is important for antiviral defense of Arabidopsis plants. Arabidopsis bak1 mutants show increased susceptibility to three different RNA viruses during compatible interactions. Furthermore, crude viral extracts but not purified virions induce several PTI marker responses in a BAK1-dependent manner. Overall, we conclude that BAK1-dependent PTI contributes to antiviral resistance in plants.

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Breaking Bad News: Dynamic Molecular Mechanisms of Wound Response in Plants

Frontiers in Plant Science ◽

10.3389/fpls.2020.610445 ◽

2020 ◽

Vol 11 ◽

Author(s):

Isaac Vega-Muñoz ◽

Dalia Duran-Flores ◽

Álvaro Daniel Fernández-Fernández ◽

Jefri Heyman ◽

Andrés Ritter ◽

...

Keyword(s):

Molecular Mechanisms ◽

Wound Response ◽

Surrounding Tissue ◽

Defense Gene Expression ◽

Defense Gene ◽

Breaking Bad ◽

Damage Recognition ◽

Pathogen Colonization ◽

Recognition And Response ◽

Molecular Patterns

Recognition and repair of damaged tissue are an integral part of life. The failure of cells and tissues to appropriately respond to damage can lead to severe dysfunction and disease. Therefore, it is essential that we understand the molecular pathways of wound recognition and response. In this review, we aim to provide a broad overview of the molecular mechanisms underlying the fate of damaged cells and damage recognition in plants. Damaged cells release the so-called damage associated molecular patterns to warn the surrounding tissue. Local signaling through calcium (Ca2+), reactive oxygen species (ROS), and hormones, such as jasmonic acid, activates defense gene expression and local reinforcement of cell walls to seal off the wound and prevent evaporation and pathogen colonization. Depending on the severity of damage, Ca2+, ROS, and electrical signals can also spread throughout the plant to elicit a systemic defense response. Special emphasis is placed on the spatiotemporal dimension in order to obtain a mechanistic understanding of wound signaling in plants.

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Molecular Crosstalk Between PAMP-Triggered Immunity and Photosynthesis

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-11-11-0301 ◽

2012 ◽

Vol 25 (8) ◽

pp. 1083-1092 ◽

Cited By ~ 97

Author(s):

Vera Göhre ◽

Alexandra M. E. Jones ◽

Jan Sklenář ◽

Silke Robatzek ◽

Andreas P. M. Weber

Keyword(s):

Defense Responses ◽

Innate Immune ◽

Energy Costs ◽

Defense Gene Expression ◽

Defense Gene ◽

Fluorescence Measurements ◽

Species Production ◽

Molecular Patterns ◽

Intrinsic Component ◽

Molecular Crosstalk

The innate immune system allows plants to respond to potential pathogens in an appropriate manner while minimizing damage and energy costs. Photosynthesis provides a sustained energy supply and, therefore, has to be integrated into the defense against pathogens. Although changes in photosynthetic activity during infection have been described, a detailed and conclusive characterization is lacking. Here, we addressed whether activation of early defense responses by pathogen-associated molecular patterns (PAMPs) triggers changes in photosynthesis. Using proteomics and chlorophyll fluorescence measurements, we show that activation of defense by PAMPs leads to a rapid decrease in nonphotochemical quenching (NPQ). Conversely, NPQ also influences several responses of PAMP-triggered immunity. In a mutant impaired in NPQ, apoplastic reactive oxygen species production is enhanced and defense gene expression is differentially affected. Although induction of the early defense markers WRKY22 and WRKY29 is enhanced, induction of the late markers PR1 and PR5 is completely abolished. We propose that regulation of NPQ is an intrinsic component of the plant's defense program.

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A receptor for herbivore-associated molecular patterns mediates plant immunity

10.1101/679803 ◽

2019 ◽

Cited By ~ 3

Author(s):

Adam D. Steinbrenner ◽

Maria Muñoz-Amatriaín ◽

Jessica Montserrat Aguilar Venegas ◽

Sassoum Lo ◽

Da Shi ◽

...

Keyword(s):

Plant Protection ◽

Plant Immunity ◽

Defense Responses ◽

Cell Surface Receptor ◽

Immune Recognition ◽

Induced Responses ◽

Surface Receptor ◽

Initial Perception ◽

Plant Herbivore ◽

Molecular Patterns

AbstractPlant-herbivore interactions are ubiquitous across nature and drive major agricultural losses. Inducible defense responses triggered through immune recognition aid in host plant protection; however, specific ligand-receptor pairs mediating the initial perception of herbivory remain unknown. Plants in the subtribe Phaseolinae detect herbivore-associated peptides in caterpillar oral secretions and the defined ligands are proteolytic fragments of chloroplastic ATP synthase termed inceptins. Using forward genetic mapping of inceptin-induced responses, we identify a cowpea (Vigna unguiculata) leucine-rich repeat receptor-like protein as an inceptin receptor (INR) sufficient for elicitor-induced responses and enhanced defense against armyworms (Spodoptera exigua). INR defines a receptor by which plants perceive herbivore-associated molecular patterns (HAMPs) and expands the paradigm of surface immune recognition to attack with mandibles.One Sentence SummaryA plant cell surface receptor directly perceives peptides associated with caterpillar herbivory.

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