Signaling in Plant-Microbe Interactions

TLDR

Plants defend against pathogens through a two‑layer immune system: PAMP‑triggered immunity (PTI) that recognizes microbial signatures, and effector‑triggered immunity (ETI) that detects pathogen effectors to activate stronger defenses. This review examines recent advances in PTI, effector functions, ETI, and downstream signaling to better understand plant immune pathways for disease control. The authors synthesize current knowledge of PTI, effector mechanisms, ETI, and downstream signaling pathways.

Abstract

Plants are attacked by different kinds of pathogens; therefore plants have evolved defense mechanism to combat the pathogen attack and diseases. Many microbial signature molecules, which are known as microbe associated or pathogen associated molecular patterns (MAMPs/PAMPs) are recognized by a plant’s primary layer of immune response, known as PAMP-triggered immunity (PTI). In the co-evolution of plant-microbe interactions, successful pathogens have acquired the ability to deliver effectors proteins directly inside plant cell to suppress PTI, allowing pathogen growth and disease. As a counter measure, plants have developed a second layer of defense system, by acquiring the ability to recognize these effector proteins via ‘Resistance’ (R) protein to trigger a defense response, known as effector triggered immunity (ETI). In this review, we discuss the developments that have taken place in understanding the PTI, effectors function, ETI and downstream signaling events. Understanding plant immune signaling pathways would be very helpful in controlling plant diseases.