DAMPs, MAMPs, and NAMPs in plant innate immunity

Abstract

BackgroundMulticellular organisms have evolved systems/mechanisms to detect various forms of danger, including attack by microbial pathogens and a variety of pests, as well as tissue and cellular damage. Detection via cell-surface receptors activates an ancient and evolutionarily conserved innate immune system.ResultPotentially harmful microorganisms are recognized by the presence of molecules or parts of molecules that have structures or chemical patterns unique to microbes and thus are perceived as non-self/foreign. They are referred to as Microbe-Associated Molecular Patterns (MAMPs). Recently, a class of small molecules that is made only by nematodes, and that functions as pheromones in these organisms, was shown to be recognized by a wide range of plants. In the presence of these molecules, termed Nematode-Associated Molecular Patterns (NAMPs), plants activate innate immune responses and display enhanced resistance to a broad spectrum of microbial and nematode pathogens. In addition to pathogen attack, the relocation of various endogenous molecules or parts of molecules, generally to the extracellular milieu, as a result of tissue or cellular damage is perceived as a danger signal, and it leads to the induction of innate immune responses. These relocated endogenous inducers are called Damage-Associated Molecular Patterns (DAMPs).ConclusionsThis mini-review is focused on plant DAMPs, including the recently discovered Arabidopsis HMGB3, which is the counterpart of the prototypic animal DAMP HMGB1. The plant DAMPs will be presented in the context of plant MAMPs and NAMPs, as well as animal DAMPs.

Pattern recognition receptors and signaling in plant–microbe interactions

“…High‐mobility group box protein (HMGB) is associated with chromatin in the nucleus and also present in the cytosol of non‐stressed cells, but its extracellular pool is immunogenic in both plants and mammals (Lotze and Tracey, ; Choi and Klessig, ). In A. thaliana , HMGB3 is released upon tissue damage during B. cinerea infection , thereby inducing PTI‐like responses and fungal resistance (Choi et al ., ).…”

“…Cutin monomers and cellulose‐derived oligomers are also immunogenic (Fauth et al ., ; Souza et al ., ). Recognition of these cell‐wall‐derived DAMPs resembles TLR2/TLR4/TLR6‐mediated recognition of degradation products from extracellular matrix in mammals (Choi and Klessig, ). Indeed, the malectin‐like domain Catharanthus roseus RLK1‐like (MLD‐CrRLK1L) receptor THE1 and the class XII LRR‐RLK MIK2 (LRR‐KISS) link cell wall disintegration to defense activation (Hematy et al ., ; Van der Does et al ., ).…”

Virus perception at the cell surface: revisiting the roles of receptor‐like kinases as viral pattern recognition receptors

“…To cope with invading pathogens, plant cells evolved a sophisticated immune system under constant pressure for dominance over the pathogens’ virulence strategies, which in turn coevolved to escape the host recognition system (Jones and Dangl, ). The first layer of the plant immune system is represented by the pattern recognition receptors (PRRs) at the cell surface, which recognize either conserved signature molecules produced by the pathogens, designated pathogen‐associated molecular patterns (PAMPs), or endogenous damage/danger signals associated with pathogen invasion, designated danger‐ or damage‐associated molecular patterns (DAMPs) (Choi and Klessig, ; Ma et al , ). The sensing of PAMPs by PRRs activates PAMP‐triggered immunity (PTI), leading to a rapid, non‐specific response to a broad range of pathogens (Ma et al , ).…”

Moving to the Field: Plant Innate Immunity in Crop Protection

“…When a pathogen becomes able to overcome these defences, disease ceases to be the exception [1]. Though a comprehensive discussion on the plant immune system is beyond the scope of this editorial, the molecular mechanisms involved in the plant immunity have been recently reviewed [2,3,4,5,6]. Kørner et al [7] emphasized the cross-talk between endoplasmic reticulum (ER) stress signaling pathways and immune responses in plants.…”

“…Luti et al [12] investigated the PAMP activity of cerato-platanin, a Cys-rich protein produced by the pathogenic ascomycete Ceratocystis platani , in Arabidopsis, by an elegant proteomic and volatilomic approach. Among plant activators, acibenzolar- S -methyl or benzothiadiazole ( S -methyl benzo[1,2,3]thiadiazole-7-carbothioate) deserves particular attention. The latter is a functional analogue of salicylic acid, a plant hormone that plays a central role in innate immunity as a co-activator of immunity-induced transcription reprogramming [13].…”