PAMP recognition and the plant–pathogen arms race

Abstract

Plants have evolved systems analogous to animal innate immunity that recognise pathogen-associated molecular patterns (PAMPs). PAMP detection is an important component of non-host resistance in plants and serves as an early warning system for the presence of potential pathogens. Binding of a PAMP to the appropriate pattern recognition receptor leads to downstream signalling events and, ultimately, to the induction of basal defence systems. To overcome non-host resistance, pathogens have evolved effectors that target specific regulatory components of the basal defence system. In turn, this has led to the evolution in plants of cultivar-specific resistance mediated by R proteins, which guard the targets of effectors against pathogen manipulation; the arms race continues.

Tomato Transcriptional Changes in Response toClavibacter michiganensissubsp.michiganensisReveal a Role for Ethylene in Disease Development

“…Additional possible Cmm PAMPs are EPS, which are produced in large amounts by the bacterium (Van den Bulk et al, 1989), or the numerous extracellular cellwall-degrading enzymes secreted by Cmm, and products of their hydrolytic activity. Only a few of the PRRs responsible for PAMP recognition have been identified to date (Ingle et al, 2006). Interestingly, we found several tomato genes encoding proteins with characteristics of cell-surface receptors that were differentially expressed in response to Cmm infection.…”

The multifaceted role of ABA in disease resistance

“…However, strong stimulation by PAMPs can lead to activation of SA-and JA-dependent defense mechanisms [48]. Given that SA-and JA-dependent defenses are predominantly active during the later stages of pathogen infection (Phase III; Figure 1), they will be unnecessary as long as the early defense barrier is sufficient to stop pathogen invasion.…”

Signals that stop the rot: Regulation of secondary metabolite defences in cereals

“…Instead, each plant cell acts autonomously and is programmed to recognise and respond to pathogens [1]. The mechanisms by which plants defend themselves include the production of secondary metabolites with antimicrobial properties and these responses are controlled by signal transduction pathways [2].…”

“…Examples of PAMPs recognised by plants include bacterial flagellin, fungal β-glucans and chitin [2,46]. Once PAMPs are perceived by a plant cell, a process termed PAMP-triggered immunity (PTI) is initiated [1]. This process involves a complex local and systemic intracellular signalling cascade promulgated through gene expression changes involving WRKY and TGA transcription factors [1].…”

“…Once PAMPs are perceived by a plant cell, a process termed PAMP-triggered immunity (PTI) is initiated [1]. This process involves a complex local and systemic intracellular signalling cascade promulgated through gene expression changes involving WRKY and TGA transcription factors [1]. In the interaction between cereals and fungi, β-glucan and chitin are representative fungal PAMPs and are polysaccharides that crosslink to form a scaffold within fungal cell walls [47].…”