Interactions between organisms, such as those between plants and microbes, require extensive signaling between and within each organism to detect and recognize the partner and elicit an appropriate response. Multiple families of small signaling peptides regulate plant interactions with beneficial or pathogenic microbes, and sometimes both. Some of these signaling peptides transmit information between different cells or organs of the host and allow plants to orchestrate a coordinated response towards microbial mutualists or pathogens. However, not only plants produce signaling peptides required for the interactions. Microbes themselves also secrete peptide signals, which are detected by host receptors and required for infection. Among these are microbial peptides mimicking those of plants, allowing mutualistic or pathogenic microbes to hijack endogenous plant signaling pathways and evade the host immune system. In this review, we provide a comprehensive summary of current knowledge on host- and microbe-derived signaling peptides and their cognate receptors regulating mutualistic and parasitic plant-microbe interactions. Furthermore, we describe how microbes hijack endogenous host signaling pathways, and discuss possible crosstalk between the plant signaling pathways controlling mutualism with those modulating immune responses to pathogens.

Receptor-like kinases (RLKs) are essential in nearly all plant life activities. To date, most RLK research focuses on their plasma membrane functions as holoreceptors. This review introduces a distin...

CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptides have emerged as key regulators of plant–microbe interactions, including arbuscular mycorr...

Throughout the life cycle of a plant, numerous responses need to be carefully regulated to ensure proper development and appropriate responses to external stimuli, and plant hormones play a crucial ro...

This study reconstructs legume nodule symbiotic cells using three-dimensional (3D) scanning electron microscopy (SEM) and uncovers that endoplasmic reticulum (ER) expansion and activation of the unfo....

Extracellular proteasomes are found in the Arabidopsis apoplastic fluid and shown to participate in biotic defense by proteolytically digesting pathogen proteins into microbe-associated molecular patt...

Eastman, Jiang, and Ficco et al. screen 165 root-associated bacteria for suppression of plant immune activation and growth restriction induced by the peptide immune elicitor flg22. They show that Dyella japonica uses the type II secreted subtilase IssA to cleave the peptide immune elicitors flg22 and AtPEP1 and suppress plant immune activation.

Plants recognize bacteria by perceiving a 22-residue epitope in flagellin. Plant-secreted SBT5.2 subtilases are found to inactivate this epitope, leading to elicitor removal and reducing costly immuni...