Ubiquitination of Receptorsomes, Frontline of Plant Immunity.

Yongming Chen,Jing Liu,Yingying Song,Daolong Dou,Guangyuan Xu

doi:10.3390/ijms23062937

Abstract

Sessile plants are constantly exposed to myriads of unfavorable invading organisms with different lifestyles. To survive, plants have evolved plasma membrane-resident pattern recognition receptors (PRRs) and intracellular nucleotide-binding domain leucine-rich repeat receptors (NLRs) to initiate sophisticated downstream immune responses. Ubiquitination serves as one of the most important and prevalent posttranslational modifications (PTMs) to fine-tune plant immune responses. Over the last decade, remarkable progress has been made in delineating the critical roles of ubiquitination in plant immunity. In this review, we highlight recent advances in the understanding of ubiquitination in the modulation of plant immunity, with a particular focus on ubiquitination in the regulation of receptorsomes, and discuss how ubiquitination and other PTMs act in concert to ensure rapid, proper, and robust immune responses.

Highlights

Sessile plants are constantly exposed to a large diversity of pathogens, including bacteria, fungi, oomycetes, nematodes, and viruses
During their evolutionary arms race with pathogens, plants have evolved a robust resistance response known as effector-triggered immunity (ETI), which is mediated by nucleotide-binding domain leucine-rich repeat proteins (NBS–LRRs or nucleotide-binding domain leucine-rich repeat receptors (NLRs)) that recognize pathogen effectors directly or through effector-induced perturbation [8]
We focus on the latest progress in the regulation of pattern recognition receptors (PRRs) and NLR signaling by ubiquitination, which is necessary for the appropriate activation of immune signaling and maintaining cellular homeostasis when a threat disappears

Summary

Introduction

Sessile plants are constantly exposed to a large diversity of pathogens, including bacteria, fungi, oomycetes, nematodes, and viruses. Plant PRRs include receptor-like kinases (RLKs) and receptor-like proteins (RLPs) with an ectodomain, a transmembrane domain, and an intracellular kinase domain for RLKs. host-adapted pathogens interfere with PTI responses by secreting effectors into the plant cell, resulting in effector-triggered susceptibility (ETS) [6,7]. Plant genomes encode a large number of E3 ligases, which are generally classified into three subgroups: the RING (really interesting new gene) and U-box type, the HECT (homologous to E6-associated protein C terminus) type, and the RBR (RING between RING) type [20] Some of these subgroups were identified to be involved in the regulation of plant immunity-related component turnover, endocytosis, and cytoplasmic transport [21–23]. The perception of flg induces the formation of FLS2 and BAK1, which in turn phosphorylates RLCK BIK1 and thereby leads to BIK1 s dissociation from the FLS2–BAK1 complex; this dissociation activates diverse downstream signaling events [25–27]. Two RING-type E3 ligases, RING-H2 FINGER A3A (RHA3A) and RHA3B, were identified to directly monoubiquinate BIK1, enabling endocytosis and signaling activation of BIK1 (Figure 1) [41]

Ubiquitination in Chitin-Triggered Immune Signaling

Intertwined Regulation of Plant Immunity via Ubiquitination and Phosphorylation

Coordinated Regulation of Plant Immunity by ADP-Ribosylation and K63-Linked Ubiquitination

Conclusions and Perspectives