Plant-microbe homeostasis: A delicate balancing act
Science Daily
https://www.sciencedaily.com/releases/2021/05/210524161804.htm
- Source:
- Max Planck Institute for Plant Breeding Research
- Summary:
- Scientists have shown that the presence of both immune-suppressive and non-suppressive bacteria in the plant root microbiota is crucial to strike a balance between plant growth and plant defense, and maintain plant-microbe homeostasis.
Plants grown in soil are colonized by diverse microbes collectively known as the plant microbiota, which is essential for optimal plant growth in nature and protects the plant host from the harmful effects of pathogenic microorganisms and insects. However, in the face of an advanced plant immune system that has evolved to recognize microbial associated-molecular patterns (MAMPs) -- conserved molecules within a microbial class -- and mount an immune response, it is unknown how soil-dwelling microbes are able to colonize plant roots. Now, MPIPZ researchers led by Paul Schulze-Lefert, and researchers from the University of Carolina led by Jeffery L. Dangl show, in two separate studies, that a subset of commensal bacteria is able to suppress a sector of the plant immune system and colonize plant roots when both immune-suppressive and non-suppressive bacteria are present, in the context of a microbial community.
Plants have evolved an innate immune system to protect themselves against pathogens, including the recognition of microbe-derived MAMPs by pattern recognition receptors (PRRs) that reside on the surface of plant cells. Recognition of MAMPs by PRRs leads to MAMP-triggered immunity (MTI), which results in the restriction of pathogen proliferation. However, left unchecked, chronic MTI can also lead to plant growth inhibition, a phenomenon known as growth-defence trade-off. Pathogens have evolved diverse mechanisms to supress MTI, a property that has, surprisingly, also been detected in a subset of non-harmful commensal bacteria of the root microbiota. These bacteria have been coined 'immune-suppressive' microbes, in contrast to 'non-suppressive' commensal microbes that cannot suppress MTI. Now, it has emerged that the presence of immune-suppressive microbes in the plant microbiota can suppress part of the host immune response, while favoring the colonization of opportunistic pathogens -- infectious microorganisms that are normally harmless to their host but can cause disease when favorable conditions arise.
Read on: https://www.sciencedaily.com/releases/2021/05/210524161804.htm