Recognition and Response in Plant PAMP ‐Triggered Immunity

Abstract

Pathogen‐associated molecular pattern (PAMP)‐triggered immunity (PTI) describes the first events after pathogen invasion, whereby the plant identifies the presence of an invader and mounts a response. A race ensues in which the pathogen deploys its array of virulence molecules that act in opposition to host defence mechanisms and promote establishment of a pathogenic niche. Since the seminal work identifying the first pathogen receptor, FLAGELLIN‐SENSING 2 (FLS2), the field has worked to define receptor complexes and downstream signalling pathways. This article describes recent progress in this area. In addition, many pathogen effectors target the PTI machinery. Thus, identifying PTI components as effector targets helps to validate those molecules as components of the defence machinery. As such, early molecular interactions are key to the outcome of infection. Indeed it is thought that nonhost resistance, in which most plants species are resistant to most pathogens, is likely to be a result of the PTI system. Key Concepts: Plants have multilayered recognition systems which detect invading pathogens. The first line of recognition involves detection of PAMPs via host pattern‐recognition receptors (PRRs). PRRs are transmembrane receptor‐like kinases or receptor‐like proteins that perceive PAMPs at the cell surface. PRRs act as a major point of control for PTI. Biogenesis and localisation of PRRs to the plasma membrane requires the proteins are processed by the secretory pathway and individual PRRs have varying requirements for endoplasmic reticulum‐quality control pathways. Following PAMP perception, a series of downstream defence responses results in PTI. Attenuation of PRR signalling is necessary to restrict immune responses.

The pathways and mechanisms of muramyl dipeptide transcellular transport mediated by PepT1 in enterogenous infection

“…When bacteria and their products invade or contact the body, the host cells can recognize the pathogen-associated (21). Activation of the downstream signals of PRR causes protective responses against infection, including releasing inflammatory cytokines, recruiting phagocytes, and DCs to mediate immune responses (22).…”

An Important Pathogen of Barley: Ramularia collo-cygni

“…Fungus, konukçu tarafından tanınmasını önlemek için lizin motifi (LysM) içeren efektörler de dahil olmak üzere farklı efektörler salgılayabilmektedir [87]. LysM içeren efektörler, konukçu reseptörleri tarafından fungus kitininin tanınmasını önleyen, patojenle ilişkili moleküler model (PAMP) olarak bilinen, konukçudaki PAMP ile tetiklenen bağışıklık (PTI) mekanizması üzerinde etkili olmaktadırlar [88]. LysM alanlarını içeren proteinler, buğday yaprak lekesi etmeni Z. tritici ve domates yaprak küfü hastalığı etmeni Cladosporium fulvum dahil olmak üzere R. collo-cygni ile yakından ilişkili birkaç fungus türünde de tanımlanmıştır [89,90].…”

ANTHRACNOSE RESISTANCE GENE2 confers fungal resistance in sorghum

“…Recognition of pathogen derived signature molecules, pathogen associated molecular patterns (PAMPs), at the cell surface is mediated by pattern recognition receptors, which initiates pattern triggered immunity (PTI). PTI is associated with varying degrees of quantitative resistance (Godfrey & Rathjen, 2001 ). Accumulation of phytoalexin 3‐deoxyanthocyanidin at the site of infection has been linked to quantitative resistance to Cs (Cui et al., 2015 ; Lo, De Verdier, & Nicholson, 1999 ; Tenkouano et al., 1993 ).…”