Jasmonate perception by inositol-phosphate-potentiated COI1-JAZ co-receptor

The Nuclear Effector MiISE23 From Meloidogyne incognita Targets JAZ Proteins and Suppresses Jasmonate Signalling, Increasing Host Susceptibility

Meloidogyne incognita is an economically important plant-parasitic nematode that can infect thousands of different plant species. During its interaction with host plants, M. incognita synthesises numerous effectors in oesophageal glands, which are then secreted into plant tissues. Here, we characterised the effector MiISE23 and found that it could suppress plant immune responses. In situ hybridisation showed that MiISE23 was expressed in the subventral glands. Transgenic Arabidopsis plants expressing MiISE23 were more susceptible to M. incognita, whereas host-derived RNAi of MiISE23 was found to decrease M. incognita infection in Arabidopsis. In vitro and in vivo experiments showed that MiISE23 repressed jasmonate (JA) signalling by directly interacting with and suppressing jasmonoyl-isoleucine (JA-Ile)-induced degradation of jasmonate ZIM-domain proteins by COI1. The expression of MiISE23 in Arabidopsis repressed the expression of JA-responsive genes and reduced the levels of endogenous JA-Ile. AtJAZ6 transgenic lines of Arabidopsis showed increased susceptibility to M. incognita infection. Collectively, our results show that MiISE23 stabilises JAZ proteins and interferes with JA signalling, revealing a novel mechanism utilised by root-knot nematodes to hijack phytohormone signalling and promote parasitism.

Role of jasmonates in plant response to temperature stress

The ambient temperature exerts a significant influence on the growth and development of plants, which are sessile organisms. Exposure to extreme temperatures, both low and high, has a detrimental impact on plant growth and development, crop yields, and even geographical distribution. Jasmonates constitute a class of lipid hormones that regulate plant tolerance to biotic and abiotic stresses. Recent studies have revealed that jasmonate biosynthesis and signaling pathways are integral to plant responses to both high and low temperatures. Exogenous application of jasmonate improves cold and heat tolerance in plants and reduces cold injury in fruits and vegetables during cold storage. Jasmonate interacts with low and high temperature key response factors and engages in crosstalk with primary and secondary metabolic pathways, including hormones, under conditions of temperature stress. This review presents a comprehensive summary of the jasmonate synthesis and signal transduction pathway, as well as an overview of the functions and mechanisms of jasmonate in response to temperature stress.

Fungi deploy host phosphate signaling disrupter

Plants have evolved sophisticated phosphate starvation response (PSR) mechanisms to maintain intracellular phosphate (Pi) homeostasis for proper growth and survival. Recently, McCombe et al. demonstrated that phytopathogens employ a novel strategy to promote disease progression by secreting conserved Nudix hydrolase effector proteins, which disrupt host Pi signaling pathways.

The MYC2-JAMYB transcriptional cascade regulates rice resistance to brown planthoppers

Plant defense against herbivores is primarily regulated by the phytohormone jasmonate (JA). At the core, JA signaling is the MYC2 transcription factor (TF) that regulates the expression of an extensive array of defense-related genes. However, the regulatory mechanisms underlying MYC2-mediated herbivore resistance in rice are not fully understood. We employed brown planthopper (BPH) bioassays, transcriptional activation assays, transcriptome profiling, targeted metabolomics and cleavage under targets and tagmentation-sequencing analysis to investigate the biological function and regulatory mechanism of the JAMYB TF. JAMYB is induced by BPH infestation and is transcriptionally regulated by MYC2. Mutations of JAMYB rendered rice plants susceptible to BPH attacks under laboratory and field conditions, indicating that JAMYB positively contributes to BPH resistance. BPH-elicited biosynthesis of phenolamides and volatile compounds was reduced in jamyb mutants compared with wild-type plants. These specialized metabolites, regulated by JAMYB, function as direct and indirect defenses to deter BPH damage or attract parasitoid wasps of BPH eggs. Furthermore, we found that JAMYB directly binds to AC motifs of key phenylpropanoid pathway genes and activates their expression, likely altering the metabolic flux for phenolamide biosynthesis. This study reveals the role of the MYC2-JAMYB module in JA-mediated rice resistance to BPH.

Perception of viral infections and initiation of antiviral defence in rice

Crop production faces persistent threats from insect-vector-borne viral diseases1,2. Recent advancements have revealed the intricate immune mechanisms that plants deploy against viral pathogens3-8. However, the molecular mechanisms through which plant hosts recognize viral infections and initiate antiviral defence at disease onset have not been elucidated. Here, through the natural infection of rice by inoculation with insect vectors carrying the natural forms of viruses, we show that viral coat proteins are perceived by the RING1-IBR-RING2-type ubiquitin ligase (RBRL), initiating the first step of the natural antiviral response in rice. RBRL subsequently targets an adaptor protein of the transcriptional repression complex of the jasmonate pathway, NOVEL INTERACTOR OF JAZ 3 (NINJA3), for degradation through the ubiquitination system, inducing jasmonate signalling and activating downstream antiviral defence. We further show that this phenomenon is a universal molecular mechanism used by rice plants to perceive viral infections and initiate antiviral signalling cascades. This approach is important not only for obtaining a deeper understanding of virus-host interactions but also for further disease resistance breeding.

Harnessing the Power of Natural Products for Targeted Protein Degradation

Natural products have garnered significant attention due to their complex chemical structures and remarkable pharmacological activities. With inherent recognition capabilities for protein surfaces, natural products serve as ideal candidates for designing proteolysis-targeting chimeras (PROTACs). The utilization of natural products in PROTAC development offers distinct advantages, including their rich chemical diversity, multitarget activities, and sustainable sourcing. This comprehensive review explores the vast potential of harnessing natural products in PROTAC research. Moreover, the review discusses the application of natural degradant technology, which involves utilizing natural product-based compounds to selectively degrade disease-causing proteins, as well as the implementation of computer-aided drug design (CADD) technology in identifying suitable targets for degradation within the realm of natural products. By harnessing the power of natural products and leveraging computational tools, PROTACs derived from natural products have the potential to revolutionize drug discovery and provide innovative therapeutic interventions for various diseases.

Recent advances in the chemistry and biology of plant oxylipin hormones

Jasmonates, including jasmonic acid (JA) and its derivatives, are lipid-based signaling molecules critical for plant growth, development, and defense. Among these, jasmonoyl-L-isoleucine (JA-Ile) has been identified as a bioactive plant hormone that mediates various physiological responses. JA-Ile functions in planta as a 'molecular glue' in protein-protein associations to induce the defense-related gene expression for plant-pathogen and plant-insect communications, and it affects many aspects of plant development and stress responses. This review explores the historical journey of jasmonate research, emphasizing the discovery of JA-Ile, its biosynthesis, function as a molecular glue, and the ligand-receptor co-evolutional aspect. The elucidation of the SCFCOI1-JAZ receptor complex and the crystallization of this co-receptor system marked significant advancements in understanding the chemical background of jasmonate biology. This review focuses on the advances in the chemistry and biology of jasmonate bioscience in the past two decades.

Verticillium dahliae effector Vd06254 disrupts cotton defence response by interfering with GhMYC3-GhCCD8-mediated hormonal crosstalk between jasmonic acid and strigolactones

Verticillium dahliae is among the most destructive plant pathogens, posing a significant threat to global cotton production. Cotton plants have developed sophisticated immune networks to inhibit V. dahliae colonization. Ingeniously, V. dahliae employs numerous virulent effectors to surmount plant immune responses. However, the pathogenic mechanisms of V. dahliae-derived effectors remain elusive. In this study, we demonstrate that the Vd06254 effector from V. dahliae disrupts the synergistic interaction between jasmonic acid (JA) and strigolactones (SL), thereby suppressing cotton immunity. Ectopic expression of Vd06254 enhanced susceptibility to both viral and V. dahliae infections in Nicotiana benthamiana and cotton, respectively. Vd06254 directly interacts with the JA pathway regulator GhMYC3. The nuclear localization signal (NLS) was found to be essential for the virulence of Vd06254 and its interaction with GhMYC3. Additionally, overexpression and knockout of GhMYC3 in cotton modified the plant's resistance to V. dahliae. Our findings further reveal that GhMYC3 inhibits the expression of GhCCD8 by binding to its promoter, potentially regulating SL homeostasis in cotton through a negative feedback loop. This repression was enhanced by Vd06254, highlighting its crucial role in modulating cotton immunity and illustrating how V. dahliae effectors reprogram cotton transcription to disrupt this regulatory mechanism.

Analysis of the Genes from Gibberellin, Jasmonate, and Auxin Signaling Under Drought Stress: A Genome-Wide Approach in Castor Bean (Ricinus communis L.)

Castor bean (Ricinus communis L.) can tolerate long periods of dehydration, allowing the investigation of gene circuits involved in drought tolerance. Genes from gibberellins, jasmonates, and auxin signaling are important for crosstalk in the developmental and environmental adaptation process to drought conditions. However, the genes related to these signals, as well as their transcription profiles under drought, remain poorly characterized in the castor bean. In the present work, genes from gibberellins, jasmonates, and auxin signaling were identified and molecularly characterized. These analyses allowed us to identify genes encoding receptors, inhibitory proteins, and transcription factors from each signaling pathway in the castor bean genome. Chromosomal distribution, gene structure, evolutionary relationships, and conserved motif analyses were performed. Expression analysis through RNA-seq and RT-qPCR revealed that gibberellins, jasmonates, and auxin signaling were modulated at multiple levels under drought, with notable changes in specific genes. The gibberellin receptor RcGID1c was downregulated in response to drought, and RcDELLA3 was strongly repressed, whereas its homologues were not, reinforcing the suggestion of a nuanced regulation of gibberellin signaling during drought. Considering jasmonate signaling, the downregulation of the transcription factor RcMYC2 aligned with the drought tolerance observed in mutants lacking this gene. Altogether, these analyses have provided insights into hormone signaling in the castor bean, unveiling transcriptional responses that enhance our understanding of high drought tolerance in this plant. This knowledge opens avenues for identifying potential candidate genes suitable for genetic manipulation in biotechnological approaches.

Overexpression of the Transcription Factor GmbZIP60 Increases Salt and Drought Tolerance in Soybean (Glycine max)

The regulation of downstream responsive genes by transcription factors (TFs) is a critical step in the stress response system of plants. While bZIP transcription factors are known to play important roles in stress reactions, their functional characterization in soybeans remains limited. Here, we identified a soybean bZIP gene, GmbZIP60, which encodes a protein containing a typical bZIP domain with a basic region and a leucine zipper region. Subcellular localization studies confirmed that GmbZIP60 is localized in the nucleus. Expression analysis demonstrated that GmbZIP60 is induced by salt stress, drought stress, and various plant hormone treatments, including abscisic acid (ABA), ethylene (ETH), and methyl jasmonate acid (MeJA). Overexpressing GmbZIP60 (OE-GmbZIP60) in transgenic soybean and rice enhanced tolerance to both salt and drought stresses. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the expression levels of abiotic stress-responsive genes were significantly higher in transgenic plants than in wild-type (WT) plants under stress conditions. Chromatin immunoprecipitation-qPCR (ChIP-qPCR) analysis further confirmed that GmbZIP60 directly binds to the promoters of abiotic stress-related genes induced by ABA, ETH, JA, and salicylic acid (SA). Overall, these findings revealed GmbZIP60 as a positive regulator of salt and drought stress tolerance.

Genome-wide insights into the nomenclature, evolution and expression of tobacco TIFY/JAZ genes

MAIN CONCLUSION

A systematic nomenclature for tobacco TIFY/JAZ proteins was established via genome-wide analysis, and the gene transcription patterns and potential functions of these proteins were analyzed as well. Intensive studies focused on the plant-specific JAZ regulators of jasmonate (JA) signaling in tobacco due to their critical roles in regulating JA-mediated development, secondary metabolism, and stress responses. JAZs comprise a subfamily of the TIFY proteins, yet the reported TIFY/JAZ regulators of tobacco spp. are tangled in naming confusion, which resulted in nomenclature chaos. Here, we identified 32 TIFY/JAZ proteins via genome-wide analysis of tobacco cultivar TN90 and obtained their homologues in Nicotiana sylvestris and Nicotiana tomentosiformis. By bioinformatic analysis, these TIFY/JAZ regulators were classified into 4 subfamilies (i.e., 21 JAZs, 5 ZIM & ZMLs, 2 TIFY8s, and 4 PPDs) based on their phylogenetic relationship to establish a systematic nomenclature, which indicated gene loss or genomic rearrangement during the formation of common tobacco. Analysis of JA-induced expression revealed that these TIFY/JAZ genes displayed distinct expression patterns in the leaves and roots upon JA treatment. Further microarray and metabolomics assays observed that 5 TIFY/JAZ genes were differentially expressed in the plants with dysfunction of COI1, the receptor protein of JA hormone and that the abundance of a series of primary and secondary metabolites was altered as well. A predicted protein interaction network of tobacco TIFY/JAZ proteins was also constructed, and it indicated that 120 proteins may interact with these regulators. Findings of this work provide valuable information about TIFY/JAZ proteins in regulating JA responses and metabolic processes in tobacco and may contribute greatly to future studies on tobacco TIFY/JAZ proteins.

Research advancements in molecular glues derived from natural product scaffolds: Chemistry, targets, and molecular mechanisms

The mechanism of action of traditional Chinese medicine (TCM) remains unclear. Historically, research on TCM has mainly focused on exploring the mechanisms of active components acting on single targets. However, it is insufficient to explain the complex mechanisms by which these active components in TCM treat diseases. In recent years, the emergence of molecular glues (MGs) theory has provided new strategies to address this issue. MGs are small molecules that can promote interactions between proteins at their interface. The characteristic of MGs is to establish connections between diverse protein structures, thereby enabling a chemically-mediated proximity effect that triggers a wide spectrum of biological functions. Natural products are the result of billions of years of evolutionary processes in the natural environment. Thus, the extensive structural diversity of natural products renders them a rich source of MGs, including polyketides, terpenoids, steroids, lignans, organic acids, alkaloids and other classes. Currently, several well-known natural MGs, including the immunosuppressants cyclosporin A (CsA) and tacrolimus (FK506), as well as the anticancer agent taxol, have been incorporated into clinical practice. Meanwhile, the advancement of new technologies is propelling the discovery of novel MGs from natural products. Thus, we primarily summarize a growing variety of MGs from natural origins reported in recent years and categorize them based on the chemical structural types. Moreover, the main sources of TCM are natural products. The discovery of natural MGs promises to provide a new perspective for the elucidation of the molecular mechanism behind the efficiency of TCM. In summary, this review aims to provide insights from the perspective of natural products that could potentially influence TCM and modern drug development.

A review of the interaction mechanisms between jasmonic acid (JA) and various plant hormones, as well as the core regulatory role of MYC2

Jasmonic acid (JA), as a defensive plant hormone, can synergistically or antagonistically interact with common hormones such as gibberellin (GA), abscisic acid (ABA), indole-3-acetic hormone acid (IAA), and ethylene (ETH) during the plant growth process, as well as interact with hormones such as melatonin (MT), brassinolide (BR), and resveratrol to regulate plant growth and development processes such as metabolite synthesis, pest and disease defense, and organ growth. The core regulatory factor MYC2 of JA mainly mediates the signal transduction pathways of these hormone interactions by interacting with other genes or regulating transcription. This article reviews the mechanism of cross-talk between JA and hormones such as ABA, GA, and salicylic acid (SA), and discusses the role of MYC2 in hormone interactions.

Plant volatile organic compounds: Emission and perception in a changing world

Volatile organic compounds (VOCs) are produced by all kingdoms of life and play crucial roles in mediating the communication between organisms and their environment through emission and perception. Plants, in particular, produce and emit an exceptional variety of VOCs that together serve as a complex chemical language facilitating intra-plant, inter-plant, plant-animal, and plant-microbe interactions. VOC signals are perceived and decrypted by receiver plants; however, the emission, composition, distribution and effective range, as well as uptake of these infochemicals depend on temperature and atmospheric chemistry in addition to their physicochemical properties. Since both emission and perception are directly affected by ongoing climate change, research into these processes is urgently needed to develop mitigation strategies against this threat to plant communication networks. In this brief review, we highlight the recent advances about plant VOC emission and perception, emphasizing the effect of the current climate crisis on these processes. Despite some progress in understanding VOC emission and perception, significant gaps remain in elucidating their molecular mechanisms in plants.

Harnessing Jasmonate Pathways: PgJAR1's Impact on Ginsenoside Accumulation in Ginseng

Ginsenosides, the most active components in Panax ginseng, exhibit pharmacological and therapeutic properties but are limited by their low abundance. Jasmonates (JAs), a class of stress-induced phytohormones, are integral in modulating plant defense responses and the biosynthesis of secondary metabolites, including ginsenosides. Jasmonoyl-isoleucine (JA-Ile), the primary bioactive JA compound, is biosynthesized by JA-Ile synthase 1 (JAR1). In this study, we cloned the 1555 bp PgJAR1 gene from ginseng roots and analyzed its structure, enzyme activity, and expression pattern. The PgJAR1 protein encompasses all the hallmark elements characteristic of the GH3 family. It exhibits N/C-terminal domains analogous to ANL, three ATP/AMP-binding motifs, and distinct secondary structures: an N-terminal beta-barrel with beta-sheets and alpha-helices, and a C-terminal beta-sheet surrounded by alpha-helices, similarly to AtGH3.11/AtJAR1. The recombinant PgJAR1 enzyme expressed in Escherichia coli BL21 specifically catalyzed jasmonic acid (JA) to JA-Ile. PgJAR1 is predominantly expressed in leaves and is upregulated by MeJA treatment. Moderate transient overexpression of PgJAR1 promoted the biosynthesis of both JA-Ile and ginsenosides, highlighting the crucial role of PgJAR1 in JA-Ile biosynthesis and its positive impact on ginsenoside accumulation. Nevertheless, elevated JA-Ile levels can impede cellular growth, reducing ginsenoside production. Consequently, balancing JA-Ile biosynthesis through PgJAR1 expression is essential for optimizing ginseng cultivation and enhancing its medicinal properties. Modulating endogenous JA-Ile levels offers a strategy for increasing ginsenoside production in ginseng plants.

Ectopic Overexpression of Rapeseed BnaNTL1 Transcription Factor Positively Regulates Plant Resistance to Sclerotinia sclerotiorum through Modulating JA Synthesis and ROS Accumulation

Oilseed rape is one of the most important oil crops worldwide. Stem rot disease of rapeseed is caused by Sclerotinia sclerotiorum, posing a threat to oil crop yield. NTL is a small class of membrane-tethered NAC transcription factors, which are stored on the membrane in dormant form, released upon stimuli, and then transported to the nucleus. Here, we identified BnaNTL1 from oilseed rape, and its relocation from the ER to the nucleus is induced by S. sclerotiorum. Plants overexpressing BnaNTL1-ΔTM (a truncated form without the transmembrane domain) are resistant to S. sclerotiorum infection and are accumulated with more JA and ROS. Genes related to the JA pathway and ROS signal were significantly induced by BnaNTL1. Furthermore, the dual-luciferase and EMSA results showed that BnaNTL1-ΔTM directly binds to the promoter regions of AOC3, LOX2, OPCL1, and PDF1.2, and it activates their expression. In summary, we identified that BnaNTL1 positively regulates plant resistance to S. sclerotiorum infection by modulating JA synthesis and ROS production.

UM171 glues asymmetric CRL3-HDAC1/2 assembly to degrade CoREST corepressors

UM171 is a potent agonist of ex vivo human haematopoietic stem cell self-renewal1. By co-opting KBTBD4, a substrate receptor of the CUL3-RING E3 ubiquitin ligase (CRL3) complex, UM171 promotes the degradation of the LSD1-CoREST corepressor complex, thereby limiting haematopoietic stem cell attrition2,3. However, the direct target and mechanism of action of UM171 remain unclear. Here we show that UM171 acts as a molecular glue to induce high-affinity interactions between KBTBD4 and HDAC1/2 to promote corepressor degradation. Through proteomics and chemical inhibitor studies, we identify the principal target of UM171 as HDAC1/2. Cryo-electron microscopy analysis of dimeric KBTBD4 bound to UM171 and the LSD1-HDAC1-CoREST complex identifies an asymmetric assembly in which a single UM171 molecule enables a pair of KELCH-repeat propeller domains to recruit the HDAC1 catalytic domain. One KBTBD4 propeller partially masks the rim of the HDAC1 active site, which is exploited by UM171 to extend the E3-neosubstrate interface. The other propeller cooperatively strengthens HDAC1 binding through a distinct interface. The overall CoREST-HDAC1/2-KBTBD4 interaction is further buttressed by the endogenous cofactor inositol hexakisphosphate, which acts as a second molecular glue. The functional relevance of the quaternary complex interaction surfaces is demonstrated by base editor scanning of KBTBD4 and HDAC1. By delineating the direct target of UM171 and its mechanism of action, we reveal how the cooperativity offered by a dimeric CRL3 E3 can be leveraged by a small molecule degrader.

Phytohormones and emerging plant growth regulators in tailoring plant immunity against viral infections

Viral infections are major contributors to crop yield loss and represent a significant threat to sustainable agriculture. Plants respond to virus attacks by activating sophisticated signalling cascades that initiate multiple defence mechanisms. Notably, several phytohormones, including salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), and ethylene (ET), are known to shape these defence responses. In recent years, various plant growth regulators (PGRs) such as melatonin, carrageenans, sulfated fucan oligosaccharides, nitric oxide (NO), brassinosteroids (BRs), and hydrogen sulfide (H2S) have also emerged as crucial regulators of plant defence responses against virus infections. Emerging evidence indicates that these PGRs coordinate with phytohormones to activate various defence strategies, including (1) stomatal closure to limit pathogen entry, (2) callose deposition to block plasmodesmata and restrict viral spread within host tissues, (3) attenuation of viral replication, and (4) activation of RNA interference (RNAi), a crucial antiviral defence response. However, the interactions and crosstalk between PGRs and phytohormones remain largely underexplored, thereby limiting our ability to develop innovative strategies for managing viral diseases. This review discusses the diverse functions and crosstalk among various phytohormones and PGRs in orchestrating the plant defence mechanisms, highlighting their impact on viral replication, movement, and intercellular transport.

Plant pathogenic fungi hijack phosphate signaling with conserved enzymatic effectors

Inorganic phosphate (Pi) is essential for life, and plant cells monitor Pi availability by sensing inositol pyrophosphate (PP-InsP) levels. In this work, we describe the hijacking of plant phosphate sensing by a conserved family of Nudix hydrolase effectors from pathogenic Magnaporthe and Colletotrichum fungi. Structural and enzymatic analyses of the Nudix effector family demonstrate that they selectively hydrolyze PP-InsP. Gene deletion experiments of Nudix effectors in Magnaporthe oryzae, Colletotrichum higginsianum, and Colletotrichum graminicola indicate that PP-InsP hydrolysis substantially enhances disease symptoms in diverse pathosystems. Further, we show that this conserved effector family induces phosphate starvation signaling in plants. Our study elucidates a molecular mechanism, used by multiple phytopathogenic fungi, that manipulates the highly conserved plant phosphate sensing pathway to exacerbate disease.

The Monochoria genome provides insights into the molecular mechanisms underlying floral heteranthery

Heteranthery, the occurrence of functionally and structurally distinct stamens within a flower, represents a striking example of convergent evolution among diverse animal-pollinated lineages. Although the ecological basis of this somatic polymorphism is understood, the developmental and molecular mechanisms are largely unknown. To address this knowledge gap, we selected Monochoria elata (Pontederiaceae) as our study system due to its typical heterantherous floral structure. We constructed a chromosome-level genome assembly of M. elata, conducted transcriptomic analyses and target phytohormone metabolome analysis to explore gene networks and hormones associated with heteranthery. We focused on three key stamen characteristics-colour, spatial patterning, and filament elongation-selected for their significant roles in stamen differentiation and their relevance to the functional diversity observed in heterantherous species. Our analyses suggest that gene networks involving MelLEAFY3, MADS-box, and TCP genes regulate stamen identity, with anthocyanin influencing colour, and lignin contributing to filament elongation. Additionally, variation in jasmonic acid and abscisic acid concentration between feeding and pollinating anthers appears to contribute to their morphological divergence. Our findings highlight gene networks and hormones associated with intra-floral stamen differentiation and indicate that whole genome duplications have likely facilitated the evolution of heteranthery during divergence from other Pontederiaceae without heteranthery.

Plant PI-PLC signaling in stress and development

Phosphoinositide-specific phospholipase C (PI-PLC) signaling is involved in various plant stress and developmental responses. Though several aspects of this lipid signaling pathway are conserved within animals and plants, clear differences have also emerged. While animal PLC signaling is characterized by the hydrolysis of PIP2 and production of IP3 and DAG as second messengers to activate Ca2+ and PKC signaling, plant PI-PLCs seem to predominantly use PIP as substrate and convert IP2 and DAG into inositolpolyphosphates and phosphatidic acid (PA) as plant second messengers. Sequencing of multiple plant genomes confirmed that plant PLC signaling evolved differently from animals, lacking homologs of the IP3 gated-Ca2+ channel, PKC and TRP channels, and with PLC enzymes resembling the PLCζ subfamily, which lacks the conserved PH domain that binds PIP2. With emerging tools in plant molecular biology, data analyses, and advanced imaging, plant PLC signaling is ready to gain momentum.

Getting attached to membranes-How plant signaling networks employ PtdIns(4,5)P2

In eukaryotes, a small subset of membrane lipids, the phosphoinositides (PIs), exert regulatory effects on membrane-associated processes with profound impact on the organism, and PIs are relevant also for the physiology and development of plants. The PI, phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) has emerged as an important regulatory player in plants, and in recent years this lipid has received substantial attention. This Update Review focuses on our current understanding of how PtdIns(4,5)P2 exerts its regulatory functions, how biosynthesis and degradation of this important regulatory lipid are controlled, and how PtdIns(4,5)P2 is linked to upstream and downstream elements within plant signalling networks.

Silencing CsMAP65-2 and CsMAP65-3 in cucumber reduces susceptibility to Meloidogyne incognita

Root knot nematodes (RKNs) induce hypertrophy and cell proliferation within the vascular cylinders of host plants, leading to the formation of giant cells (GCs) that are enlarged, multinucleate cells with high metabolic activity. These GCs are formed through repeated karyokinesis without cytokinesis and are accompanied by significant changes in cytoskeleton organization. In this study, two microtubule-binding protein genes, CsMAP65-2 and CsMAP65-3, are upregulated in cucumber roots upon RKNs infection, specifically at 3, 96, and 120 hpi. GUS expression analysis further confirmed the induction of CsMAP65-2 and CsMAP65-3 in both roots and nematode-induced galls. Silencing CsMAP65-2 or CsMAP65-3 using VIGS technology led to a reduction in gall size and number, as well as a decrease in GCs number (24.98% for CsMAP65-2; 19.48% for CsMAP65-3) and area (6% for CsMAP65-2; 4% for CsMAP65-3), compared to control plants. Furthermore, qRT-PCR analysis revealed upregulation of CsMYC2、CsPR1、CsPAD4, and CsPDF1 in CsMAP65-2 silenced lines and upregulation of CsFRK1 in CsMAP65-3 silenced lines, while CsJAZ1 was downregulated in both silenced lines. These findings suggest that CsMAP65-2 and CsMAP65-3 are critical for GCs development during RKN infection and provide a foundation for breeding nematode-resistant cucumber varieties. This research also offers insights for developing sustainable nematode management strategies in gourd crop cultivation.

Design, synthesis and systemic acquired resistance of 2-benzothiadiazolylquinoline-4-carboxamides by COI1 based virtual screening

Coronatine-insensitive 1 (COI1) has been identified as a target receptor of plant elicitor coronatine (COR). To discover novel plant elicitor leads, most of the potential molecules among 129 compounds discovered from the ZINC database by docking based virtual screening targeting COI1 were quinoline amides. On this lead basis, 2-benzothiadiazolylquinoline-4-carboxamides were rationally designed and synthesized for bioassay. All target compounds did not show significantly in vitro antifungal activity, compounds 4d, 4e and 4o displayed good in vivo systemic acquired resistance activity for Arabidopsis thaliana against Hyaloperonospora arabidopsidis isolate Noco2 with over 80% of inhibitory rate at the concentration of 50 μM. These results indicate that 2-benzothiadiazolylquinoline-4-carboxamides are promising plant elicitor leads for further study.

ERF114/115/109 are essential for jasmonate-repressed non-canonical JAZ8 activity in JA signaling

Jasmonate (JA), a key plant hormone, regulates various aspects of plant development and stress responses, primarily through the degradation of canonical jasmonate-ZIM domain (JAZ) proteins by the SCFCOI1 complex. While JAZ8, a non-canonical JAZ protein lacking the degron signal, has been shown to repress JA responses, the mechanism by which JA inhibits JAZ8 activity remains unclear. Here, we demonstrate that Arabidopsis ethylene response factor 114 (ERF114), ERF115, and ERF109 regulate JA signaling through interacting with JAZ8. This interaction disrupts the formation of the MYC2/3/4-JAZ8 and root hair defective 6 (RHD6)-JAZ8 complexes. We show that ERF114 positively regulates JA-induced transcriptional responses and that JA-promoted root hair growth is highly alleviated in erf114 mutants. Furthermore, the transcription of ERF114/115/109 is induced by JA in an MYC2-dependent manner, thus forming a positive feedback loop in JA signaling. Collectively, this study reveals a regulatory pathway in which ERF114/115/109 regulate JA signaling by targeting non-canonical JAZ proteins.

A multiprotein regulatory module, MED16-MBR1&2, controls MED25 homeostasis during jasmonate signaling

Mediator25 (MED25) has been ascribed as a signal-processing and -integrating center that controls jasmonate (JA)-induced and MYC2-dependent transcriptional output. A better understanding of the regulation of MED25 stability will undoubtedly advance our knowledge of the precise regulation of JA signaling-related transcriptional output. Here, we report that Arabidopsis MED16 activates JA-responsive gene expression by promoting MED25 stability. Conversely, two homologous E3 ubiquitin ligases, MED25-BINDING RING-H2 PROTEIN1 (MBR1) and MBR2, negatively regulate JA-responsive gene expression by promoting MED25 degradation. MED16 competes with MBR1&2 to bind to the von Willebrand Factor A (vWF-A) domain of MED25, thereby antagonizing the MBR1&2-mediated degradation of MED25 in vivo. In addition, we show that MED16 promotes hormone-induced interactions between MYC2 and MED25, leading to the activation of JA-responsive gene expression. Collectively, our findings reveal a multiprotein regulatory module that robustly and tightly maintains MED25 homeostasis, which determines the strength of the transcriptional output of JA signaling.

SlVQ15 recruits SlWRKY30IIc to link with jasmonate pathway in regulating tomato defence against root-knot nematodes

Tomato is one of the most economically important vegetable crops in the world and has been seriously affected by the devastating agricultural pest root-knot nematodes (RKNs). Current understanding of tomato resistance to RKNs is quite limited. VQ motif-containing family proteins are plant-specific regulators; however, whether and how tomato VQs regulate resistance to RKNs is unknown. Here, we found that SlVQ15 recruited SlWRKY30IIc to coordinately control tomato defence against the RKN Meloidogyne incognita without affecting plant growth and productivity. The jasmonate (JA)-ZIM domain (JAZ) repressors of the phytohormone JAs signalling associated and interfered with the interaction of SlVQ15 and SlWRKY30IIc. In turn, SlWRKY30IIc bound to SlJAZs promoters and cooperated with SlVQ15 to repress their expression, whereas this inhibitory effect was antagonized by SlJAZ5, forming a feedback regulatory mechanism. Moreover, SlWRKY30IIc expression was directly regulated by SlMYC2, a SlJAZ-interacting negative regulator of resistance to RKNs. In conclusion, our findings revealed that a regulatory circuit of SlVQ15-SlWRKY30IIc and the JA pathway fine-tunes tomato defence against the RKN M. incognita, and provided candidate genes and clues with great potential for crop improvement.

A frameshift mutation in JAZ10 resolves the growth versus defense dilemma in rice

CRISPR-Cas9 genome editing systems have revolutionized plant gene functional studies by enabling the targeted introduction of insertion-deletions (INDELs) via the nonhomologous end-joining (NHEJ) pathway. Frameshift-inducing INDELs can introduce a premature termination codon and, in other instances, can lead to the appearance of new proteins. Here, we found that mutations in the rice jasmonate (JA) signaling gene OsJAZ10 by CRISPR-Cas9-based genome editing did not affect canonical JA signaling. However, a type of mutant with an INDEL that yielded a novel frameshift protein named FJ10 (Frameshift mutation of JAZ10), exhibited enhanced rice growth and increased resistance to brown planthopper attacks. Overexpression of FJ10 in wild-type plants phenocopies OsJAZ10 frameshift mutants. Further characterization revealed that FJ10 interacts with Slender Rice 1 (OsSLR1) and F-box/Kelch 16 (OsFBK16). These interactions disrupt the function of OsSLR1 in suppressing gibberellin-mediated growth and the function of OsFBK16 in repressing lignin-mediated defense responses, respectively. Field experiments with FJ10-expressing plants demonstrate that this protein uncouples the growth-defense tradeoff, opening broad avenues to obtain cultivars with enhanced yield without compromised defenses.

Receptor-like Kinase GOM1 Regulates Glume-Opening in Rice

Glume-opening of thermosensitive genic male sterile (TGMS) rice (Oryza sativa L.) lines after anthesis is a serious problem that significantly reduces the yield and quality of hybrid seeds. However, the molecular mechanisms regulating the opening and closing of rice glumes remain largely unclear. In this study, we report the isolation and functional characterization of a glum-opening mutant after anthesis, named gom1. gom1 exhibits dysfunctional lodicules that lead to open glumes following anthesis. Map-based cloning and subsequent complementation tests confirmed that GOM1 encodes a receptor-like kinase (RLK). GOM1 was expressed in nearly all floral tissues, with the highest expression in the lodicule. Loss-of-function of GOM1 resulted in a decrease in the expression of genes related to JA biosynthesis, JA signaling, and sugar transport. Compared with LK638S, the JA content in the gom1 mutant was significantly reduced, while the soluble sugar, sucrose, glucose, and fructose contents were significantly increased in lodicules after anthesis. Together, we speculated that GOM1 regulates carbohydrate transport in lodicules during anthesis through JA and JA signaling, maintaining a higher osmolality in lodicules after anthesis, which leads to glum-opening.

Amide conjugates of the jasmonate precursor cis-(+)-12-oxo-phytodienoic acid regulate its homeostasis during plant stress responses

Jasmonates are a family of oxylipin phytohormones regulating plant development and growth and mediating "defense versus growth" responses. The upstream JA biosynthetic precursor cis-(+)-12-oxo-phytodienoic acid (cis-OPDA) acts independently of CORONATIVE INSENSITIVE 1-mediated JA signaling in several stress-induced and developmental processes. However, its perception and metabolism are only partially understood. An isoleucine analog of the biologically active JA-Ile, OPDA-Ile, was detected years ago in wounded leaves of flowering plants, opening up the possibility that conjugation of cis-OPDA to amino acids might be a relevant mechanism for cis-OPDA regulation. Here, we extended the analysis of amino acid conjugates of cis-OPDA and identified naturally occurring OPDA-Val, OPDA-Phe, OPDA-Ala, OPDA-Glu, and OPDA-Asp accumulating in response to biotic and abiotic stress in Arabidopsis (Arabidopsis thaliana). The OPDA amino acid conjugates displayed cis-OPDA-related plant responses in a JA-Ile-dependent manner. We also showed that the synthesis and hydrolysis of cis-OPDA amino acid conjugates are mediated by members of the amidosynthetase GRETCHEN HAGEN 3 and the amidohydrolase INDOLE-3-ACETYL-LEUCINE RESISTANT 1/ILR1-like families. Thus, OPDA amino acid conjugates function in the catabolism or temporary storage of cis-OPDA in stress responses instead of acting as chemical signals per se.

Jasmonate induces translation of the Arabidopsis transfer RNA-binding protein YUELAO1, which activates MYC2 in jasmonate signaling

Jasmonate is ubiquitous in the plant kingdom and regulates multiple physiological processes. Although jasmonate signaling has been thoroughly investigated in Arabidopsis thaliana, most studies have focused on the transcriptional mechanisms underlying various jasmonate responses. It remains unclear whether (and how) translation-related pathways help improve transcription efficiency to modulate jasmonate signaling, which may enable plants to respond to stressful conditions effectively. Here, we demonstrate that jasmonate induces translation of the transfer RNA (tRNA)-binding protein YUELAO 1 (YL1) via a specific region in its 3' untranslated region (3' UTR). YL1 and its homolog YL2 redundantly stimulate jasmonate responses such as anthocyanin accumulation and root growth inhibition, with the YL1 3' UTR being critical for YL1-promoted jasmonate responses. Once translated, YL1 acts as an activator of the MYC2 transcription factor through direct interaction, and disrupting YL1 3' UTR impairs the YL1-mediated transcriptional activation of MYC2. YL1 enhances jasmonate responses mainly in a MYC2-dependent manner. Together, these findings reveal a translational mechanism involved in jasmonate signaling and advance our understanding of the transcriptional regulation of jasmonate signaling. The YL1 3' UTR acts as a crucial signal transducer that integrates translational and transcriptional regulation, allowing plants to respond to jasmonate in a timely fashion.

Dinor-12-oxo-phytodienoic acid conjugation with amino acids inhibits its phytohormone bioactivity in Marchantia polymorpha

Jasmonates (JAs) are important phytohormones that regulate plant tolerance to biotic and abiotic stresses, and developmental processes. Distinct JAs in different plant lineages activate a conserved signaling pathway that mediates these responses: dinor-12-oxo-phytodienoic acid (dn-OPDA) isomers in bryophytes and lycophytes, and JA-Ile in most vascular plants. In many cases, the final responses triggered by these phytohormones depend on the accumulation of specialized metabolites. To identify compounds regulated by the dn-OPDA pathway in the liverwort Marchantia polymorpha, untargeted metabolomic analyses were carried out in response to wounding, a stress that activates the dn-OPDA pathway. A previously unreported group of molecules was identified from these analyses: dn-OPDA-amino acid conjugates (dn-OPDA-aas). Their accumulation after wounding and herbivory was confirmed by targeted metabolic profiling in Marchantia and in all species in which we previously detected dn-iso-OPDA. Mutants in GRETCHEN-HAGEN 3A (MpGH3A) failed to accumulate dn-OPDA-aa conjugates and showed a constitutive activation of the OPDA pathway and increased resistance to herbivory. Our results show that dn-iso-OPDA bioactivity is reduced by amino acid conjugation. Therefore, JA conjugation in land plants plays dichotomous roles: jasmonic acid conjugation with isoleucine (Ile) produces the bioactive JA-Ile in tracheophytes, whereas conjugation of dn-iso-OPDA with different amino acids deactivates the phytohormone in bryophytes and lycophytes.

Using native and synthetic genes to disrupt inositol pyrophosphates and phosphate accumulation in plants

Inositol pyrophosphates are eukaryotic signaling molecules that have been recently identified as key regulators of plant phosphate sensing and homeostasis. Given the importance of phosphate to current and future agronomic practices, we sought to design plants, which could be used to sequester phosphate, as a step in a phytoremediation strategy. To achieve this, we expressed diadenosine and diphosphoinositol polyphosphate phosphohydrolase (DDP1), a yeast (Saccharomyces cerevisiae) enzyme demonstrated to hydrolyze inositol pyrophosphates, in Arabidopsis thaliana and pennycress (Thlaspi arvense), a spring annual cover crop with emerging importance as a biofuel crop. DDP1 expression in Arabidopsis decreased inositol pyrophosphates, activated phosphate starvation response marker genes, and increased phosphate accumulation. These changes corresponded with alterations in plant growth and sensitivity to exogenously applied phosphate. Pennycress plants expressing DDP1 displayed increases in phosphate accumulation, suggesting that these plants could potentially serve to reclaim phosphate from phosphate-polluted soils. We also identified a native Arabidopsis gene, Nucleoside diphosphate-linked moiety X 13 (NUDIX13), which we show encodes an enzyme homologous to DDP1 with similar substrate specificity. Arabidopsis transgenics overexpressing NUDIX13 had lower inositol pyrophosphate levels and displayed phenotypes similar to DDP1-overexpressing transgenics, while nudix13-1 mutants had increased levels of inositol pyrophosphates. Taken together, our data demonstrate that DDP1 and NUDIX13 can be used in strategies to regulate plant inositol pyrophosphates and could serve as potential targets for engineering plants to reclaim phosphate from polluted environments.

Mitogen-activated protein kinase 4 phosphorylates MYC2 transcription factors to regulate jasmonic acid signaling and herbivory responses in maize

Regulation of responses induced by herbivory and jasmonic acid (JA) remains poorly understood in the important staple crop maize (Zea mays). MYC2 is the key transcription factor regulating many aspects of JA signaling, while mitogen-activated protein kinases (MAPKs or MPKs) play important roles in various plant physiological processes. Using a combination of reverse genetics, transcriptome analysis, and biochemical assays, we elucidated the important role of mitogen-activated protein kinase 4 (MPK4) in maize resistance to insects and in JA signaling. Silencing MPK4 increased the JA and jasmonoyl-isoleucine levels elicited by wounding or simulated herbivory but decreased maize resistance to armyworm (Mythimna separata) larvae. We showed that MPK4 is required for transcriptional regulation of many genes responsive to methyl jasmonate, indicating the important role of maize MPK4 in JA signaling. Biochemical analyses indicated that MPK4 directly phosphorylates MYC2s at Thr115 of MYC2a and Thr112 of MYC2b. Compared with nonphosphorylated MYC2s, phosphorylated MYC2s were more prone to degradation and exhibited enhanced transactivation activity against the promoters of several benzoxazinoid biosynthesis genes, which are important for maize defense against insects. This study reveals the essential role of maize MPK4 in JA signaling and provides insights into the functions of MAPKs in maize.

Insight into Rice Resistance to the Brown Planthopper: Gene Cloning, Functional Analysis, and Breeding Applications

This review provides a comprehensive overview of the current understanding of rice resistance to the brown planthopper (BPH), a major pest that poses significant threats to rice production through direct feeding damage and by transmitting viruses such as Rice grassy stunt virus (RGSV) and Rice ragged stunt virus (RRSV). We highlight the emergence of various BPH biotypes that have overcome specific resistance genes in rice. Advances in genetic mapping and cloning have identified 17 BPH resistance genes, classified into typical R genes encoding nucleotide-binding leucine-rich repeat (NLR) proteins and atypical R genes such as lectin receptor kinases and proteins affecting cell wall composition. The molecular mechanisms of these genes involve the activation of plant defense pathways mediated by phytohormones like jasmonic acid (JA), salicylic acid (SA), and ethylene, as well as the production of defensive metabolites. We also examine the complex interactions between BPH salivary proteins and rice defense responses, noting how salivary effectors can both suppress and trigger plant immunity. The development and improvement of BPH-resistant rice varieties through conventional breeding and molecular marker-assisted selection are discussed, including strategies like gene pyramiding to enhance resistance durability. Finally, we outline the challenges and future directions in breeding for durable BPH resistance, emphasizing the need for continued research on resistance mechanisms and the development of rice varieties with broad-spectrum and long-lasting resistance.

In vivo and in silico evaluation of the phytoalexin-eliciting activity in common bean (Phaseolus vulgaris L.) of jasmonoyl-l-isoleucine analogs having a pyrazolidin-3-one ring

Jasmonates are phytohormones derived from jasmonic acid that regulate metabolic processes involved in the chemical response of plants to biotic and abiotic stress. As part of this response, some species synthesize de novo compounds with biological activity against some pathogens. In this work, nine analogs of jasmonoyl-l-isoleucine containing a pyrazolidin-3-one core were tested in their activity to elicit the production of phytoalexins (daidzein, genistein, coumestrol, and phaseollin) in common bean (Phaseolus vulgaris L.) cultivars when added exogenously. Some variations in selected parts of the analogs, such as the side chain, the linker, or the conjugated amino acid, allowed the establishment of qualitative relations with the observed activity. The analogs were tested at two levels of concentration, and the observed activity was, in most cases, higher than the observed for methyl jasmonate at 0.5 mM, even at the lower level. Seedlings treated with most heterocyclic compounds exhibited significantly higher amounts of phaseollin than untreated seedlings. Jasmonoyl-l-isoleucine analogs having a pyrazolidin-3-one ring trigger the production of phytoalexins and can be used for crop protection. Additionally, the protein-complex receptor involved in the jasmonate signaling mechanism was modeled by homology for P. vulgaris, using that for Arabidopsis thaliana as a template. After being modeled, it was assessed and used to qualitatively correlate the observed activity values and the vina scores from the docking of the tested analogs.

Rice E3 ubiquitin ligases: From key modulators of host immunity to potential breeding applications

To combat pathogen attacks, plants have developed a highly advanced immune system, which requires tight regulation to initiate robust defense responses while simultaneously preventing autoimmunity. The ubiquitin-proteasome system (UPS), which is responsible for degrading excess or misfolded proteins, has vital roles in ensuring strong and effective immune responses. E3 ligases, as key UPS components, play extensively documented roles in rice immunity by modulating the ubiquitination and degradation of downstream substrates involved in various immune signaling pathways. Here, we summarize the crucial roles of rice E3 ligases in both pathogen/microbe/damage-associated molecular pattern-triggered immunity and effector-triggered immunity, highlight the molecular mechanisms by which E3 ligases function in rice immune signaling, and emphasize the functions of E3 ligases as targets of pathogen effectors for pathogenesis. We also discuss potential strategies for application of immunity-associated E3 ligases in breeding of disease-resistant rice varieties without growth penalty. This review provides a comprehensive and updated understanding of the sophisticated and interconnected regulatory functions of E3 ligases in rice immunity and in balancing immunity with growth and development.

Western corn rootworm resistance in maize persists in the absence of jasmonic acid

MAIN CONCLUSION

Larva growth, survival, and development speed were not affected by the absence of jasmonic acid (JA) indicating that JA does not have a direct role in maize resistance to western corn rootworm. Jasmonic acid (JA) is a plant hormone that regulates multiple physiological processes including defense against herbivory by chewing insects. Previous research showed its importance for resistance to aboveground herbivory. While few studies have investigated the role of JA in resistance to belowground root-feeding herbivores, none has directly tested the role of JA in such resistance. In this study, we used an opr7opr8 double mutant to directly test the role of JA in resistance to western corn rootworm (Diabrotica virgifera virgifera, WCR), a devastating and specialist pest of maize. The opr7opr8 double mutant is deficient in JA accumulation as we found that it does not accumulate JA nor JA-Ile independently of exposure to WCR. We found no significant difference in growth (body mass), survival, and development of WCR larvae in response to JA deficiency, suggesting that disruption of JA biosynthesis does not impact resistance in maize roots to WCR. Additionally, we observed no significant effect on loss of root tissue caused by WCR associated with JA deficiency, while we found a reduction in shoot growth (mass) associated with WCR herbivory in the opr7opr8 mutant that was not observed in the wildtype. This suggested a role for JA in aboveground growth response to WCR herbivory rather than resistance to WCR.

Genome-wide identification of the eggplant jasmonate ZIM-domain (JAZ) gene family and functional characterization of SmJAZ10 in modulating chlorophyll synthesis in leaves

The jasmonate ZIM-domain (JAZ) plays a crucial role in regulating several economic traits in crops. Despite its importance, the characterization of the SmJAZ gene family in eggplant (Solanum melongena L.) has not been documented. In this study, we identified 13 SmJAZ distributed across 9 chromosomes, which were categorized into 5 subgroups based on phylogenetic analysis. Both of them possess TIFY-motif and CCT_2 domains with varying degrees of variation. Promoter cis-element analysis predicted 42 distributed cis-elements that respond to diverse signals. Gene expression analysis demonstrated that SmJAZ exhibited responsiveness to JA, ABA, NaCl, PEG, 4 °C, blue light, and UV-B treatments. Moreover, microRNA interaction predictions identified 150 potential miRNAs, among which ath-miR5021 was found to target 8 SmJAZ mRNAs. Yeast two-hybrid assays demonstrated that most of the SmJAZs were able to interact with SmMYC2 and SmNINJA and could form JAZ-JAZ complexes. Subcellular localization analysis unveiled a diverse array of intranuclear and extranuclear localization signals for SmJAZs. Overexpressing of SmJAZ10 could decrease the chlorophyll content of seedling leaves, and the transcriptome showed that genes related to chlorophyll synthesis, such as SmCHLH, SmPORA, and SmGLK2, underwent down-regulated expression. Overall, these findings serve as a valuable resource for leveraging JA signaling to enhance eggplant quality.

Cryo-EM structure and molecular mechanism of the jasmonic acid transporter ABCG16

Jasmonates (JAs) are a class of oxylipin phytohormones including jasmonic acid (JA) and derivatives that regulate plant growth, development and biotic and abiotic stress. A number of transporters have been identified to be responsible for the cellular and subcellular translocation of JAs. However, the mechanistic understanding of how these transporters specifically recognize and transport JAs is scarce. Here we determined the cryogenic electron microscopy structure of JA exporter AtABCG16 in inward-facing apo, JA-bound and occluded conformations, and outward-facing post translocation conformation. AtABCG16 structure forms a homodimer, and each monomer contains a nucleotide-binding domain, a transmembrane domain and an extracellular domain. Structural analyses together with biochemical and plant physiological experiments revealed the molecular mechanism by which AtABCG16 specifically recognizes and transports JA. Structural analyses also revealed that AtABCG16 features a unique bifurcated substrate translocation pathway, which is composed of two independent substrate entrances, two substrate-binding pockets and a shared apoplastic cavity. In addition, residue Phe608 from each monomer is disclosed to function as a gate along the translocation pathway controlling the accessing of substrate JA from the cytoplasm or apoplast. Based on the structural and biochemical analyses, a working model of AtABCG16-mediated JA transport is proposed, which diversifies the molecular mechanisms of ABC transporters.

Jasmonate-mediated polyamine oxidase 6 drives herbivore-induced polyamine catabolism in rice

Polyamines (PAs) along with their conjugated forms, are important mediators of plant defense mechanisms against both biotic and abiotic stresses. Flavin-containing polyamine oxidases (PAOs) regulate PA levels through terminal oxidation. To date, the role of PAOs in plant-herbivore interaction remains poorly understood. We discovered that infestation by the brown planthopper (BPH) disrupts PA homeostasis within the leaf sheaths of rice plants, which co-occurs with the upregulation of OsPAO6, a tissue-specific inducible, apoplast-localized enzyme that regulates the terminal catabolism of spermidine (Spd) and spermine. Functional analysis using CRISPR-Cas9 genome-edited plants revealed that pao6 mutants accumulated significantly higher levels of Spd and phenylpropanoid-conjugated Spd in response to BPH infestation compared to wild-type controls. In addition, BPH feeding on pao6 mutants led to increased honeydew excretion and plant damage by female adults, consistent with in vitro experiments in which Spd enhanced BPH feeding. Furthermore, OsPAO6 transcription is regulated by jasmonate (JA) signaling, and it is dependent on MYC2, which directly binds to the G-box-like motif in the OsPAO6 promoter. Our findings reveal an important role of OsPAO6 in regulating polyamine catabolism in JA-induced responses triggered by herbivore attacks in rice.

Loss-of-function of LIGULELESS1 activates the jasmonate pathway and promotes maize resistance to corn leaf aphids

Corn leaf aphids (Rhopalosiphum maidis) are highly destructive pests of maize (Zea mays) that threaten growth and seed yield, but resources for aphid resistance are scarce. Here, we identified an aphid-resistant maize mutant, resistance to aphids 1 (rta1), which is allelic to LIGULELESS1 (LG1). We confirmed LG1's role in aphid resistance using the independent allele lg1-2, allelism tests and LG1 overexpression lines. LG1 interacts with, and increases the stability of ZINC-FINGER PROTEIN EXPRESSED IN INFLORESCENCE MERISTEM (ZIM1), a central component of the jasmonic acid (JA) signalling pathway, by disturbing its interaction with the F-box protein CORONATINE INSENSITIVE 1a (COI1a). Natural variation in the LG1 promoter was associated with aphid resistance among inbred lines. Moreover, a loss-of-function mutant in the LG1-related gene SPL8 in the dicot Arabidopsis thaliana conferred aphid resistance. This study revealed the aphid resistance mechanism of lg1, providing a theoretical basis and germplasm for breeding aphid-resistant crops.

Spatiotemporal expression analysis of jasmonic acid and saponin-related genes uncovers a potential biosynthetic regulation in Panax notoginseng

BACKGROUND

Sanqi, the root of Panax notoginseng, has long been recognized for its therapeutic effects on cardiovascular diseases. Saponins, including ginsenosides and notoginsenosides, are the main bioactive components of P. notoginseng. The biosynthesis of saponins is closely related to the defense responses orchestrated by endogenous hormones.

RESULTS

To provide new insights into the underlying role of phytohormone jasmonic acid (JA) in the synthesis and regulation of saponins, we performed an ultra-performance liquid chromatography analysis of different tissues of P. notoginseng aged 2-4 years. Moreover, by combined evaluation of saponin content and transcriptome profiling of each tissue, the spatial and temporal distribution of saponins was analyzed. N notoginsenoside R1, ginsenoside Rb1 and ginsenoside Rd accumulated in the underground tissues, including the root, tuqi, fibril and rhizome. In agreement with this data, the corresponding genes of the endogenous hormone JAs, especially coronatine insensitive 1 (COI1) and myelocytomatosis proteins 2 (MYC2), were predominantly expressed in the underground tissues. The tissue- and age-specific distribution of saponins was consistent with the expression of genes involved in JA biosynthetic, metabolic and signaling pathways.

CONCLUSION

The present study has revealed the temporal and spatial effects of endogenous phtohormones in the synthesis and regulation of notoginsenosides, which will provide a significant impact on improving the ecological planting technology, cultivating new high-quality varieties and protecting the rare resources of medicinal P. notoginseng. © 2024 Society of Chemical Industry.

Genome-wide survey and expression analysis of JAZ genes in watermelon (Citrullus lanatus)

BACKGROUND JAZ: (Jasmonate ZIM-domain) genes play important roles in plant growth and JA signaling pathway which is correlated with fruit ripening process. However, there have been few reports on the genome-wide identification of JAZ genes in watermelon and its relationship with fruit ripening. METHODS AND RESULTS: In this study, bioinformatics approaches were employed to identify ClaJAZ genes of watermelon at the genome-wide levels. Further exploration delved into the phylogenetic relationships, chromosomal mappings, promoter dynamics, expression, and architectural features of the JAZ genes. The results showed that a total of 9 ClaJAZ genes unevenly distributed across six chromosomes were identified in the watermelon genome, and they all have conserved Jas and TIFY domains. These JAZ genes were divided into four distinct groups with five genes involved in inter-chromosomal tandem duplication events, and members of the same subgroup exhibited a high degree of similarity in their gene structure and protein motif patterns. Analysis of the promoter regions of the ClaJAZ genes indicated the presence of cis-acting elements associated with hormonal responses, stress, and developmental processes. Gene expression analysis through real-time quantitative PCR (qRT-PCR) showed that there were spatiotemporal differences in the expression of ClaJAZ genes at various stages of fruit development. Among them, ClaJAZ7 has the highest level of transcriptional expression and showed strong promoter activity. CONCLUSIONS: This study conducted a comprehensive analysis of the ClaJAZ genes and provided insights into the role of ClaJAZ in the development and ripening of watermelon fruit.

Touch, light, wounding: how anaesthetics affect plant sensing abilities

KEY MESSAGE

Anaesthetics affect not only humans and animals but also plants. Plants exposed to certain anaesthetics lose their ability to respond adequately to various stimuli such as touch, injury or light. Available results indicate that anaesthetics modulate ion channel activities in plants, e.g. Ca2+ influx. The word anaesthesia means loss of sensation. Plants, as all living creatures, can also sense their environment and they are susceptible to anaesthesia. Although some anaesthetics are often known as drugs with well-defined target to their animal/human receptors, some other are promiscuous in their binding. Both have effects on plants. Application of general volatile anaesthetics (GVAs) inhibits plant responses to different stimuli but also induces strong cellular response. Of particular interest is the ability of GVAs inhibit long-distance electrical and Ca2+ signalling probably through inhibition of GLUTAMATE RECEPTOR-LIKE proteins (GLRs), the effect which is surprisingly very similar to inhibition of nerve impulse transmission in animals or human. However, GVAs act also as a stressor for plants and can induce their own Ca2+ signature, which strongly reprograms gene expression . Down-regulation of genes encoding enzymes of chlorophyll biosynthesis and pigment-protein complexes are responsible for inhibited de-etiolation and photomorphogenesis. Vesicle trafficking, germination, and circumnutation movement of climbing plants are also strongly inhibited. On the other hand, other cellular processes can be upregulated, for example, heat shock response and generation of reactive oxygen species (ROS). Upregulation of stress response by GVAs results in preconditioning/priming and can be helpful to withstand abiotic stresses in plants. Thus, anaesthetic drugs may become a useful tool for scientists studying plant responses to environmental stimuli.

Role of TIR1/AFB family genes during grafting in Carya cathayensis

Auxins play significant roles in plant growth and development. The transporter inhibitor response1/auxin signaling F-box (TIR1/AFB) gene family encodes the auxin receptor proteins and plays an essential role in the auxin signaling pathway. Here we identified and characterized the TIR1/AFB family in Carya cathayensis (Cc) plants (named as CcTIR1/AFB). Seven CcTIR1/AFBs were identified and further confirmed by cloning. All proteins encoded by these genes conservatively contained two domains, the F-box and leucine-rich repeat (LRR) domains. The CcTIR1/AFBs were located in the nucleus. Phylogenetic analysis suggested that CcTIR1/AFBs were evenly scattered in four different subgroups. The cis-acting element analysis indicates that CcTIR1/AFBs might be activated by auxin. The spatial and temporal expression of CcTIR1/AFBs during grafting suggested that both CcAFB1 and CcAFB2 in scions and CcAFB4 in the rootstocks were significantly upregulated at 3 days after grafting, which indicated the specialization of three CcAFBs during grafting. The Y2H assay indicated that three CcAFBs were capable of interacting with CcIAA16, CcIAA27b, and CcIAA29a, among which CcAFB4 interacted strongly with CcIAA1 and CcIAA16. Our study provides the opportunity to understand the potential role of not only CcTIR1/AFBs but also special CcAFBs (CcAFB1, CcAFB2, and CcAFB4), which is a great aspect to further explore the molecular mechanism during the grafting process.

Ethyl acetate extract of Artemisia argyi improves the resistance of cotton to Verticillium dahliae by activating the immune response

Verticillium wilt, a significant pathogen affecting cotton, has historically been challenging to control, posing a substantial threat to the sustainable development of the cotton industry. This study demonstrates that resistance to Verticillium dahliae in cotton can be enhanced by treating the roots with an ethyl acetate extract (EAAA) extracted from Artemisia argyi. The mechanisms by which EAAA activates immunity in cotton were elucidated by examining the expression levels of resistance genes post-treatment, evaluating salicylic acid (SA) and jasmonic acid (JA) levels, analyzing transcriptome data, and employing virus-induced gene silencing (VIGS) technology. Additionally, pot experiments were conducted to validate the efficacy of EAAA in controlling Verticillium wilt. The flavonoid content in EAAA was qualitatively analyzed using Ultra-Performance Liquid Chromatography coupled with Tandem Mass Spectrometry (UPLC-MS/MS), identifying three specific flavonoids that were further screened to verify their roles in activating cotton immunity. Cotton plants treated with EAAA exhibited reduced leaf chlorosis and browning in the vascular bundles. Genes involved in SA and JA synthesis and signaling in the root system were highly expressed, resulting in increased levels of SA and JA. Transcriptome analysis revealed that most upregulated differentially expressed genes were primarily enriched in the Mitogen-Activated Protein Kinase (MAPK) signaling pathway. Two specific genes, RLK and MAPKKK18, were identified through VIGS technology as key regulators of the immune pathway in cotton. The flavonoid monomer activation experiment demonstrated that eupatilin, hispidulin, jaceosidin, and a mixture of these three could induce the expression of cotton-related resistance genes. Collectively, these findings provide a research basis for the development of EAAA as a natural plant immune-inducing agent against cotton Verticillium wilt.

The inositol phosphate signalling network in physiology and disease

Combinatorial substitution of phosphate groups on the inositol ring gives rise to a plethora of inositol phosphates (InsPs) and inositol pyrophosphates (PP-InsPs). These small molecules constitute an elaborate metabolic and signalling network that influences nearly every cellular function. This review delves into the knowledge accumulated over the past decades regarding the biochemical principles and significance of InsP metabolism. We focus on the biological actions of InsPs in mammals, with an emphasis on recent findings regarding specific target proteins. We further discuss the roles of InsP metabolism in contributing to physiological homeostasis and pathological conditions. A deeper understanding of InsPs and their metabolic pathways holds the potential to address unresolved questions and propel advances towards therapeutic applications.

BpTCP19 targets BpWRKY53 to negatively regulate jasmonic acid- and dark-induced leaf senescence in Betula platyphylla

TCP (TEOSINTE-LIKE1, CYCLOIDEA, and PROLIFERATING CELL FACTOR1) is a plant-specific transcription factor that has garnered significant attention due to its wide-ranging involvement in the regulation of plant growth or developmental processes. However, the molecular mechanisms through which TCP genes orchestrate leaf senescence have not been extensively elucidated. BpTCP19, a member of the PCF subfamily in Betula platyphylla, and has high homology to AtTCP19. BpTCP19 displayed pronounced downregulation in response to methyl jasmonate (MeJA) and dark treatment. Overexpressing BpTCP19 in Betula platyphylla led to a delay in leaf senescence, resulting in prolonged leaf greenness under both MeJA and dark conditions. Transcriptome analysis revealed that overexpression of BpTCP19 induced alterations in the expression levels of genes linked to cell proliferation, hormone signaling transduction, and leaf senescence, including the early responsive factor BpWRKY53. Furthermore, through Yeast one-hybrid assays and GUS analysis, BpTCP19 was shown to bind to the promoter region of BpWRKY53, suppressing its expression and thereby retarding leaf senescence. This study elucidates the physiological and molecular functions of BpTCP19 as a central transcriptional regulatory module in leaf senescence and provides a potential target gene for delaying leaf senescence by mitigating sensitivity to external aging signals such as Jasmonic acid (JA) and darkness.

Time-Course Transcriptome Analysis Reveals Distinct Transcriptional Regulatory Networks in Resistant and Susceptible Grapevine Genotypes in Response to White Rot

Grapevine (Vitis vinifera L.) is a globally significant economic crop. However, its widely cultivated varieties are highly susceptible to white rot disease. To elucidate the mechanisms of resistance in grapevine against this disease, we utilized time-ordered gene co-expression network (TO-GCN) analysis to investigate the molecular responses in the grapevine varieties 'Guifeimeigui' (GF) and 'Red Globe' (RG). An assessment of their resistance demonstrated that GF is highly resistant to white rot, whereas RG is highly susceptible. We conducted transcriptome sequencing and a TO-GCN analysis on leaf samples from GF and RG at seven time points post-infection. Although a significant portion of the differentially expressed genes related to disease resistance were shared between GF and RG, the GF variety rapidly activated its defense mechanisms through the regulation of transcription factors during the early stages of infection. Notably, the gene VvLOX3, which is a key enzyme in the jasmonic acid biosynthetic pathway, was significantly upregulated in GF. Its upstream regulator, Vitvi08g01752, encoding a HD-ZIP family transcription factor, was identified through TO-GCN and yeast one-hybrid analyses. This study provides new molecular insights into the mechanisms of grapevine disease resistance and offers a foundation for breeding strategies aimed at enhancing resistance.