Chemical genetics reveals cross-regulation of plant developmental signaling by the immune peptide-receptor pathway.

Cells sense and integrate multiple signals to coordinate a response. A receptor-kinase signaling pathway for plant stomatal development shares components with the immunity pathway. The mechanism ensuring their signal specificities remains unclear.

Activation of three targets by a TAL effector confers susceptibility to bacterial blight of cotton.

Bacterial transcription activator-like effectors (TALEs) promote pathogenicity by activating host susceptibility (S) genes. To understand the pathogenicity and host adaptation of Xanthomonas citri pv. malvacearum (Xcm), we assemble the genome and the TALE repertoire of three recent Xcm Texas isolates.

Modulation of stress granule dynamics by phosphorylation and ubiquitination in plants.

The Arabidopsis tandem CCCH zinc finger 1 (TZF1) is an RNA-binding protein that plays a pivotal role in plant growth and stress response. In this report, we show that TZF1 contains two intrinsically disordered regions necessary for its localization to stress granules (SGs). TZF1 recruits mitogen-activated protein kinase (MAPK) signaling components and an E3 ubiquitin ligase KEEP-ON-GOING (KEG) to SGs.

Mechanistic study of SCOOPs recognition by MIK2-BAK1 complex reveals the role of N-glycans in plant ligand-receptor-coreceptor complex formation.

Ligand-induced receptor and co-receptor heterodimerization is a common mechanism in receptor kinase (RK) signalling activation. SERINE-RICH ENDOGENOUS PEPTIDEs (SCOOPs) mediate the complex formation of Arabidopsis RK MIK2 and co-receptor BAK1, triggering immune responses. Through structural, biochemical and genetic analyses, we demonstrate that SCOOPs use their SxS motif and adjacent residues to bind MIK2 and the carboxy-terminal GGR residues to link MIK2 to BAK1.

An emerging connected view: Phytocytokines in regulating stomatal, apoplastic, and vascular immunity.

Foliar pathogens exploit natural openings, such as stomata and hydathodes, to invade plants, multiply in the apoplast, and potentially spread through the vasculature. To counteract these threats, plants dynamically regulate stomatal movement and apoplastic water potential, influencing hydathode guttation and water transport. This review highlights recent advances in understanding how phytocytokines, plant small peptides with immunomodulatory functions, regulate these processes to limit pathogen entry and proliferation.

The antagonistic role of an E3 ligase pair in regulating plant NLR-mediated autoimmunity and fungal pathogen resistance.

Plant immune homeostasis is achieved through a balanced immune activation and suppression, enabling effective defense while averting autoimmunity. In Arabidopsis, disrupting a mitogen-activated protein (MAP) kinase cascade triggers nucleotide-binding leucine-rich-repeat (NLR) SUPPRESSOR OF mkk1/2 2 (SUMM2)-mediated autoimmunity. Through an RNAi screen, we identify PUB5, a putative plant U-box E3 ligase, as a critical regulator of SUMM2-mediated autoimmunity.

Perfluorooctanesulfonic Acid Alters the Plant's Phosphate Transport Gene Network and Exhibits Antagonistic Effects on the Phosphate Uptake.

Per- and polyfluoroalkyl substances (PFASs), with significant health risks to humans and wildlife, bioaccumulate in plants. However, the mechanisms underlying plant uptake remain poorly understood. This study deployed transcriptomic analysis coupled with genetic and physiological studies using to investigate how plants respond to perfluorooctanesulfonic acid (PFOS), a long-chain PFAS.

Unlocking Nature's Defense: Plant Pattern Recognition Receptors as Guardians Against Pathogenic Threats.

Embedded in the plasma membrane of plant cells, receptor kinases (RKs) and receptor proteins (RPs) act as key sentinels, responsible for detecting potential pathogenic invaders. These proteins were originally characterized more than three decades ago as disease resistance (R) proteins, a concept that was formulated based on Harold Flor's gene-for-gene theory. This theory implies genetic interaction between specific plant R proteins and corresponding pathogenic effectors, eliciting effector-triggered immunity (ETI).

Dual phosphorylation of DGK5-mediated PA burst regulates ROS in plant immunity.

Phosphatidic acid (PA) and reactive oxygen species (ROS) are crucial cellular messengers mediating diverse signaling processes in metazoans and plants. How PA homeostasis is tightly regulated and intertwined with ROS signaling upon immune elicitation remains elusive. We report here that Arabidopsis diacylglycerol kinase 5 (DGK5) regulates plant pattern-triggered immunity (PTI) and effector-triggered immunity (ETI).

Small holes, big impact: Stomata in plant-pathogen-climate epic trifecta.

The regulation of stomatal aperture opening and closure represents an evolutionary battle between plants and pathogens, characterized by adaptive strategies that influence both plant resistance and pathogen virulence. The ongoing climate change introduces further complexity, affecting pathogen invasion and host immunity. This review delves into recent advances on our understanding of the mechanisms governing immunity-related stomatal movement and patterning with an emphasis on the regulation of stomatal opening and closure dynamics by pathogen patterns and host phytocytokines.

Arabidopsis RNA polymerase II C-terminal domain phosphatase-like 1 targets mitogen-activated protein kinase cascades to suppress plant immunity.

Mitogen-activated protein kinase (MAPK) cascades play pivotal roles in plant defense against phytopathogens downstream of immune receptor complexes. The amplitude and duration of MAPK activation must be strictly controlled, but the underlying mechanism remains unclear. Here, we identified Arabidopsis CPL1 (C-terminal domain phosphatase-like 1) as a negative regulator of microbe-associated molecular pattern (MAMP)-triggered immunity via a forward-genetic screen.

The PTI-suppressing Avr2 effector from Fusarium oxysporum suppresses mono-ubiquitination and plasma membrane dissociation of BIK1.

Plant pathogens use effector proteins to target host processes involved in pathogen perception, immune signalling, or defence outputs. Unlike foliar pathogens, it is poorly understood how root-invading pathogens suppress immunity. The Avr2 effector from the tomato root- and xylem-colonizing pathogen Fusarium oxysporum suppresses immune signalling induced by various pathogen-associated molecular patterns (PAMPs).

dsRNA-induced immunity targets plasmodesmata and is suppressed by viral movement proteins.

Emerging evidence indicates that in addition to its well-recognized functions in antiviral RNA silencing, dsRNA elicits pattern-triggered immunity (PTI), likely contributing to plant resistance against virus infections. However, compared to bacterial and fungal elicitor-mediated PTI, the mode-of-action and signaling pathway of dsRNA-induced defense remain poorly characterized. Here, using multicolor in vivo imaging, analysis of GFP mobility, callose staining, and plasmodesmal marker lines in Arabidopsis thaliana and Nicotiana benthamiana, we show that dsRNA-induced PTI restricts the progression of virus infection by triggering callose deposition at plasmodesmata, thereby likely limiting the macromolecular transport through these cell-to-cell communication channels.

A phospho-switch constrains BTL2-mediated phytocytokine signaling in plant immunity.

Enabling and constraining immune activation is of fundamental importance in maintaining cellular homeostasis. Depleting BAK1 and SERK4, the co-receptors of multiple pattern recognition receptors (PRRs), abolishes pattern-triggered immunity but triggers intracellular NOD-like receptor (NLR)-mediated autoimmunity with an elusive mechanism. By deploying RNAi-based genetic screens in Arabidopsis, we identified BAK-TO-LIFE 2 (BTL2), an uncharacterized receptor kinase, sensing BAK1/SERK4 integrity.

Disarm resistance: Fungal effectors target WAK alternative splicing variant for virulence.

Molecular interactions between pathogen effectors and plant immunity underpin the arms race of disease resistance and susceptibility. In a recently published Cell Reports paper, Zuo et al. reported the mechanistic characterization of Fusarium graminearum CFEM effectors that dampen ZmWAK17-mediated defenses in maize (Zea mays).

Phytocytokine signalling reopens stomata in plant immunity and water loss.

Stomata exert considerable effects on global carbon and water cycles by mediating gas exchange and water vapour. Stomatal closure prevents water loss in response to dehydration and limits pathogen entry. However, prolonged stomatal closure reduces photosynthesis and transpiration and creates aqueous apoplasts that promote colonization by pathogens.

Knowing me, knowing you: Self and non-self recognition in plant immunity.

Perception of non-self molecules known as microbe-associated molecular patterns (MAMPs) by host pattern recognition receptors (PRRs) activates plant pattern-triggered immunity (PTI). Pathogen infections often trigger the release of modified-self molecules, termed damage- or danger-associated molecular patterns (DAMPs), which modulate MAMP-triggered signaling to shape the frontline of plant immune responses against infections. In the context of advances in identifying MAMPs and DAMPs, cognate receptors, and their signaling, here, we focus on the most recent breakthroughs in understanding the perception and role of non-self and modified-self patterns.

Deubiquitinating enzymes UBP12 and UBP13 stabilize the brassinosteroid receptor BRI1.

Protein ubiquitination is a dynamic and reversible post-translational modification that controls diverse cellular processes in eukaryotes. Ubiquitin-dependent internalization, recycling, and degradation are important mechanisms that regulate the activity and the abundance of plasma membrane (PM)-localized proteins. In plants, although several ubiquitin ligases are implicated in these processes, no deubiquitinating enzymes (DUBs), have been identified that directly remove ubiquitin from membrane proteins and limit their vacuolar degradation.

A tale of many families: calcium channels in plant immunity.

Plants launch a concerted immune response to dampen potential infections upon sensing microbial pathogen and insect invasions. The transient and rapid elevation of the cytosolic calcium concentration [Ca2+]cyt is among the essential early cellular responses in plant immunity. The free Ca2+ concentration in the apoplast is far higher than that in the resting cytoplasm.

Malectin-like receptor kinases as protector deities in plant immunity.

Plant malectin-like receptor kinases (MLRs), also known as Catharanthus roseus receptor-like kinase-1-like proteins, are well known for their functions in pollen tube reception and tip growth, cell wall integrity sensing, and hormonal responses. Recently, mounting evidence has indicated a critical role for MLRs in plant immunity. Here we focus on the emerging functions of MLRs in modulating the two-tiered immune system mediated by cell-surface-resident pattern recognition receptors (PRRs) and intracellular nucleotide-binding leucine-rich repeat receptors (NLRs).

Stomata in a state of emergency: HO is the target locked.

Stomatal movements are essential for plants to regulate photosynthesis rate, water status, and immunity. Upon stress stimulation, the production of hydrogen peroxide (HO) in the apoplasts and its accumulation within the guard cells are among key determinatives for stomatal closure. The regulatory mechanisms of HO production and transport under plant-pathogen interaction and drought stress response in stomata are important fields of research.