Defense Responses Research Articles

Quercetin, a natural flavonoid induced by the spider mite Tetranychus urticae or alamethicin, is involved in the defense of lima bean against spider mites.

Phaseolus lunatus, commonly known as the lima bean, is a leguminous crop cultivated in various regions worldwide. It is native to tropical America and is extensively grown in both tropical and temperate climates. Lima beans are highly nutritious and versatile, serving not only as a food and vegetable, but also as a source of green manure. During cultivation, lima beans can be vulnerable to numerous pests, including the spider mite, Tetranychus urticae. In large-scale outbreaks, T. urticae can cause significant yield losses or even crop failure, posing a serious threat to agricultural production. The treatment of lima bean plants with T. urticae or alamethicin (ALA) has been shown to enhance their insect-resistant defense responses. Understanding the transcriptional and metabolic mechanisms underlying these defense responses to T. urticae and ALA is crucial for improving herbivore resistance in lima bean crops. By integrated analysis of transcriptomics and metabolomics data, we found that both T. urticae and ALA treatments significantly induced the flavonoid biosynthesis pathway. Both treatments increased the flavonoid content in lima bean leaves by upregulating the expression of key genes in this pathway, potentially contributing to enhanced resistance to phytophagous insects. Notably, quercetin has been shown to reduce the number of eggs per female and survival rate of T. urticae. These findings provide a novel theoretical basis for understanding the response mechanisms of lima beans to T. urticae and ALA, while highlighting potential metabolites and genes that could be targeted to improve plant resistance to spider mite damage. © 2025 Society of Chemical Industry.

Nitric oxide as integral element in priming- induced tolerance and plant stress memory.

The beneficial effects of priming technology are aimed at the promotion of growth and development and stress tolerance in plants. Different seed pre-treatment and vegetative priming approaches (osmo-, chemical, physical, hormonal, redox treatments) increase the level of nitric oxide (NO) being an active contributor to growth regulation and defence responses. On the other hand, seed pre-treatment or vegetative priming mainly with the NO donor, sodium nitroprusside (SNP) helps to mitigate different abiotic stresses like salinity, cold, drought, excess metals. The effect of SNP/NO covers the alleviation of stress-specific effects (e.g. reduction of cadmium uptake in case of cadmium loading, improvement of water balance in case of drought), as well as general effects, such as alleviating oxidative stress. Seed pre-treatment or vegetative priming with SNP/NO up-regulates antioxidant enzymes at the activity level and increases the amount of a wide range of non-enzymatic antioxidants. However, due to adverse effects of SNP we urge the testing of other conventional NO donors (e.g. S-nitrosoglutathione) as well as new substances with more favourable properties (e.g. NO-releasing nanomaterials, plasmas, plasma treated liquids, combined donors) as seed pre-treating and vegetative priming materials. This review gives further suggestions on the methodology and future directions of fundamental research in relation to NO-associated pre-treatment and priming.

Cross-sectional study of proteomic differences between moderate and severe psoriasis

Although an ongoing understanding of psoriasis vulgaris (PV) pathogenesis, little is known about the proteomic differences between moderate and severe psoriasis. In this cross-sectional study, we evaluated the proteomic differences between moderate and severe psoriasis using data-independent acquisition mass spectrometry (DIA-MS). 173 differentially expressed proteins (DEPs) were significantly differentially expressed between the two groups. Among them, 85 proteins were upregulated, while 88 were downregulated (FC ≥ ± 1.5, P < 0.05). Eighteen DEPs were mainly enriched in the IL − 17 signalling pathway, Neutrophil extracellular trap formation, Neutrophil degranulation and NF − kappa B signalling pathway, which were associated with psoriasis pathogenesis. Ingenuity pathway Analysis (IPA) identified TNF and TDP53 as the top upstream up-regulators, while Lipopolysaccharide and YAP1 were the top potential down-regulators. The main active pathways were antimicrobial peptides and PTEN signalling, while the inhibitory pathways were the neutrophil extracellular trap pathway, neutrophil degranulation, and IL-8 signalling. 4D-parallel reaction monitoring (4D-PRM) suggested that KRT6A were downregulated in severe psoriasis. Our data identify Eighteen DEPs as biomarkers of disease severity, and are associated with IL − 17 signalling pathway, Neutrophil extracellular trap formation, NF − kappa B signalling pathway, and defence response to the bacterium. Targeting these molecules and measures to manage infection may improve psoriasis’s severity and therapeutic efficacy.

Induction of defence responses in apple trees by treatment with products of natural origin

Induction of defence responses in apple trees by treatment with products of natural origin

Atypical RXLR effectors are involved in Phytophthora cactorum pathogenesis

Abstract RXLR effectors are pathogenic factors secreted from oomycetes to manipulate the immunity of the host. Typical RXLR effectors contain an RXLR-dEER motif at the N-terminus, whereas atypical RXLRs show variations on this motif. The oomycete Phytophthora cactorum is known to infect over 200 plant species, resulting in significant agricultural economic losses. Although genome-wide identification and functional analyses of typical RXLRs from P. cactorum have been performed, little is known of atypical PcaRXLRs. Here, we identified RXLRs, both typical and atypical, in P. cactorum and compared them with those of other oomycete pathogens. Fewer RXLRs were identified in P. cactorum compared with other Phytophthora species, possibly due to fewer duplication events of RXLRs. In contrast, the percentage of atypical RXLRs was higher in P. cactorum than in other species, suggesting significant roles in P. cactorum pathogenesis. Analysis of RXLR gene expression showed that most were transcribed, suggesting their functionality. Transient expression of two atypical RXLRs in Nicotiana benthamiana showed that they induced necrosis dependent on host SGT1 and HSP90. Furthermore, two additional atypical RXLRs suppressed the defense response in N. benthamiana and promoted P. cactorum infection. These results demonstrate the vital role of atypical RXLRs in P. cactorum and provide valuable information on their evolutionary patterns and interactions with host plants.

Abstract A013: Shikonin, a strong inhibitor of Phosphoinositide 3-Kinase (PI3K) and Mitogen-Activated Protein (MAP) Kinase pathways, induces cell death in UV-B irradiated B16F10 melanoma cells

Abstract Ultraviolet (UV) radiation-induced skin damage plays a pivotal role in the pathogenesis of melanoma, a highly aggressive and fatal form of skin cancer. Shikonin, naturally occurring nathoquinone , is well-known for its inhibitory effects on phosphoinositide 3-kinase (PI3K) and mitogen-activated protein (MAP) kinase signaling pathways. It has previously been demonstrated to exert effects against various non-melanoma skin cancers. In this study, we investigated the effects of Shikonin treatment on UVB-irradiated B16F10 melanoma cells, revealing a dose-dependent reduction in cell viability and an enhancement of apoptosis. Invitro findings indicate that the pro-apoptotic effects of shikonin in UVB-exposed B16F10 cells are mediated by several mechanisms, including the generation of reactive oxygen species (ROS), modulation of the antioxidant defense response, and mitochondrial membrane potential (ΔΨM) depolarization. Further supporting the apoptotic role of Shikonin, we observed DNA fragmentation, caspase activation, poly(ADP-ribose) polymerase (PARP) cleavage, and an increase in sub-G2 cell populations. Shikonin treatment also significantly attenuated MEK-ERK signaling, influenced the PI3K/Akt pathway, and potentially inhibited UVB-induced nuclear translocation of NF-κB. Additionally, co-treatment with UVB and Shikonin led to a decrease in the Bcl-2/Bax ratio and upregulated the expression of pro-apoptotic proteins Bax and caspases. Collectively, these data suggest that Shikonin may act as a potential therapeutic agent for melanoma when combined with UVB exposure, providing a novel avenue for future treatment strategies. Citation Format: Aalim Maqsood Bhat, Sheikh Tasduq Abdullah. Shikonin, a strong inhibitor of Phosphoinositide 3-Kinase (PI3K) and Mitogen-Activated Protein (MAP) Kinase pathways, induces cell death in UV-B irradiated B16F10 melanoma cells. [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Targeted Therapies in Combination with Radiotherapy; 2025 Jan 26-29; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2025;31(2_Suppl):Abstract nr A013.

Differential responses of Bradyrhizobium sp. SUTN9-2 to plant extracts and implications for endophytic interactions within different host plants

Bradyrhizobium sp. strain SUTN9-2 demonstrates cell enlargement, increased DNA content, and efficient nitrogen fixation in response to rice (Oryza sativa) extract. This response is attributed to the interaction between the plant’s cationic antimicrobial peptides (CAMPs) and the Bradyrhizobium BacA-like transporter (BclA), similar to bacteroid in legume nodules. The present study reveals that SUTN9-2 can also establish functional endophytic interactions with chili (Capsicum annuum) and tomato (Solanum lycopersicum) plants. When exposed to extracts from chili and tomato, SUTN9-2 exhibits cell elongation, polyploidy, and reduced cell viability, with the effects being less pronounced for tomato extract. Transcriptomic and cytological analyses revealed that genes associated with CAMP resistance, nitrogen metabolism, nitrogen fixation, defense responses, and secretion systems were upregulated, while genes related to the cell cycle and certain CAMP-resistance mechanisms were downregulated, particularly in response to chili extract. This study suggests that SUTN9-2 likely evolves resistance mechanisms against CAMPs found in rice, chili, and tomato plants through mechanisms involving the protease-chaperone DegP, AcrAB-TolC multidrug efflux pumps, and polysaccharides. These mechanisms facilitate efflux, degradation, and the formation of protective barriers to resist CAMPs. Such adaptations enable SUTN9-2 to persist and colonize host plants despite antimicrobial pressures, influencing its viability, cell differentiation, and nitrogen fixation during endophytic interactions with various plant hosts.

A bi-kinase module sensitizes and potentiates plant immune signaling.

Systemic signaling is an essential hallmark of multicellular life. Pathogen encounter occurs locally but triggers organ-scale and organismic immune responses. In plants, elicitor perception provokes systemically expanding Ca2+ and H2O2 signals conferring immunity. Here, we identify a Ca2+ sensing bi-kinase module as becoming super-activated through mutual phosphorylation and as imposing synergistically enhanced NADPH oxidase activation. A combined two-layer bi-kinase/substrate phospho-code allows for sensitized signaling initiation already by near-resting elevations of Ca2+ concentration. Subsequently, it facilitates further signal wave proliferation with minimal Ca2+ amplitude requirement, triggering protective defense responses throughout the plant. Our study reveals how plants build and perpetuate trans-cellular immune signal proliferation while avoiding disturbance of ongoing cellular signaling along the path of response dissemination.

Proteomic Variation in the Oral Secretion of Spodoptera exigua and Spodoptera littoralis Larvae in Response to Different food Sources

The Spodoptera genus is defined as the pest-rich genus because it contains some of the most destructive lepidopteran crop pests, characterized by a wide host range. During feeding, the caterpillars release small amounts of oral secretion (OS) onto the wounded leaves. This secretion contains herbivore-induced molecular patterns (HAMPs) that activate the plant defense response, as well as effectors that may inhibit or diminish the plant’s anti-herbivory response. In this study, we explored the protein components of the OS of two Spodoptera species, Spodoptera exigua and Spodoptera littoralis. We identified 336 and 276 proteins, respectively, with a major role in digestion. Using a label-free quantitative proteomics approach, we investigated changes in protein abundance in the OS of both species after switching from a laboratory artificial diet to detached pepper and tomato leaves. Several proteins, such as various lipases, polycalin and a β-1,3-glucan binding protein, were more abundant in the OS of leaf-fed larvae in both species. Conversely, a tryptophan-aspartic acid (WD)-repeat containing protein significantly decreased upon feeding on plant leaves in both species. Phenotypic plasticity dependent on each Spodoptera-plant combination was observed for several peptidases, potentially related to the need to overcome the effects of proteinase inhibitors differentially produced by the two plant species, and for several REPAT proteins, possibly related to the specific modulation of each Spodoptera-plant interaction. Altogether, our results provide useful information for understanding the interaction of these two polyphagous Spodoptera species with the host plants, and help to identify evolutionary traits that may influence the outcome of herbivory in each of these two related species.

Crosstalk Between Abiotic and Biotic Stresses Responses and the Role of Chloroplast Retrograde Signaling in the Cross-Tolerance Phenomena in Plants

In the natural environment, plants are simultaneously exposed to multivariable abiotic and biotic stresses. Typical abiotic stresses are changes in temperature, light intensity and quality, water stress (drought, flood), microelements availability, salinity, air pollutants, and others. Biotic stresses are caused by other organisms, such as pathogenic bacteria and viruses or parasites. This review presents the current state-of-the-art knowledge on programmed cell death in the cross-tolerance phenomena and its conditional molecular and physiological regulators, which simultaneously regulate plant acclimation, defense, and developmental responses. It highlights the role of the absorbed energy in excess and its dissipation as heat in the induction of the chloroplast retrograde phytohormonal, electrical, and reactive oxygen species signaling. It also discusses how systemic- and network-acquired acclimation and acquired systemic resistance are mutually regulated and demonstrates the role of non-photochemical quenching and the dissipation of absorbed energy in excess as heat in the cross-tolerance phenomenon. Finally, new evidence that plants evolved one molecular system to regulate cell death, acclimation, and cross-tolerance are presented and discussed.

Stress resilience in plants: the complex interplay between heat stress memory and resetting.

Heat stress (HS) poses a major challenge to plants and agriculture, especially during climate change-induced heatwaves. Plants have evolved mechanisms to combatHS and remember past stress. This memory involves lasting changes in specific stress responses, enabling plants to better anticipate and react to future heat events. HS memory is a multi-layered cellular phenomenon that, in addition to epigenetic modifications, involves changes in protein quality control, metabolic pathways and broader physiological adjustments. An essential aspect of modulating stress memory is timely resetting, which restores defense responses to baseline levels and optimizes resource allocation for growth. Balancing stress memory with resetting enables plants to withstand stress while maintaining growth and reproductive capacity. In this review, we discuss mechanisms and regulatory layers of HS memory and resetting, highlighting their critical balance for enhancing stress resilience and plant fitness. We primarily focus on the model plant Arabidopsis thaliana due to the limited research on other species and outline key areas for future study.

The role of the jasmonate signalling transcription factors MYC2/3/4 in circadian clock-mediated regulation of immunity in Arabidopsis.

Plants are exposed to pathogens at specific, yet predictable times of the day-night cycle. In Arabidopsis, the circadian clock influences temporal differences in susceptibility to the necrotrophic pathogen Botrytis cinerea. The jasmonic acid (JA) pathway regulates immune responses against B. cinerea. The paralogous basic helix-loop-helix transcription factors MYC2, MYC3 and MYC4 are primary regulators of the JA pathway, but their role in regulating temporal variation in immunity is untested. This study aimed to investigate the roles of the MYC transcription factors in the temporal defence response to B. cinerea. We inoculated leaves from wild-type, myc single-, double- and triple-knockout mutants, and lines overexpressing MYC2, MYC3 or MYC4, with B. cinerea at two times of day in constant light, and compared lesion sizes. The presence of MYC2, MYC3 or MYC4 alone was sufficient to maintain temporal variation in susceptibility, but this was abolished in the myc234 triple-knockout mutant. Constitutive expression of MYC2, MYC3 or MYC4 abolished time-of-day differences in susceptibility. The data suggest that MYC2, MYC3 and MYC4 function redundantly in regulating temporal defence responses against B. cinerea and are a point of convergence between the JA pathway and the circadian clock in Arabidopsis.This article is part of the Theo Murphy meeting issue 'Circadian rhythms in infection and immunity'.

Arsenic-induced modulation of virulence and drug resistance in Pseudomonas aeruginosa.

Arsenic contamination of water sources, whether from natural or industrial origins, represents a significant risk to human health. However, its impact on waterborne pathogens remains understudied. This research explores the effects of arsenic exposure on the opportunistic pathogen Pseudomonas aeruginosa, a bacterium found in diverse environments. The arsenic exposure at concentrations of 0.12-20 mg/L As(III) resulted in rapid growth arrest of P. aeruginosa. Moreover, arsenic exposure significantly reduced the production of key virulence factors such as elastase (by 1.48- to 9.24-fold), pyocyanin, and flagella while increasing siderophore and extracellular polysaccharide production (by 1.44-1.75 and 1.36-2.59 times, respectively). Proteomic analysis revealed that both low (0.12 mg/L) and high (1.2 mg/L) As(III) levels activated an antioxidant defense response, with upregulation of Fnr-2, TrxB2, and Ohr. Furthermore, arsenic-induced the overexpression of multidrug resistance efflux proteins MexAB-OprM, MexCD-OprJ, and MexEF-OprN. At the same time, proteins associated with quorum sensing (QS), type III secretion system (T3SS), pyocyanin biosynthesis, and flagellar assembly were downregulated. In vitro assays confirmed that arsenic reduced bacterial virulence and significantly enhanced survival and proliferation under antibiotic treatment. These results indicate that arsenic exposure modulates the virulence and antibiotic resistance of P. aeruginosa, raising concerns about the public health risks posed by the convergence of arsenic-contaminated water and multidrug-resistant bacteria.

Cell deconvolution-based integrated time-series network of whole blood transcriptome reveals systemic antiviral activities and cell-specific immunological changes against PRRSV infection

Porcine reproductive and respiratory syndrome (PRRS) causes significant economic losses in the swine industry. However, the molecular mechanisms behind the common and cell type-specific systemic responses during PRRS virus (PRRSV) infection are not well understood. In this study, we collected viremia data, antibody levels, and whole-blood RNA-seq data obtained from eight PRRSV-infected piglets. We utilised a cell deconvolution approach to calculate cell type enrichment, constructed a time-serial gene co-expression network with differentially expressed genes, and conducted functional annotations. Three significant modules were identified within the network. The changes associated with viremia revealed an upregulated expression of genes related to antiviral activity. In the T-cell- and NK-cell-specific modules, infection led to an increased T-cell population and upregulation of genes related to T-cell defence responses. Conversely, in the monocyte- and neutrophil-specific module, genes involved in inflammatory responses were downregulated due to a decrease in monocyte proportion. This study highlights the time-series antiviral activities associated with viremia and the transcriptomic changes associated with immune responses in specific cell types. The findings provide comprehensive insights into host responses to PRRSV infection, including diagnostic biomarkers.

Green revolution gene drives adaptation of Arabidopsis to the extremely high altitude.

To elucidate the process of adaptation, particularly the traits subject to natural selection and the molecular mechanisms underlying their natural variation, is one of the primary objectives of evolutionary biology. The uplifted landscape offers an excellent framework for understanding how organisms adapt to dramatic climatic gradients. To investigate the genetic basis of plant adaptation to the extremely high altitude, we first compared the genomic and phenotypic variations of two closely related Arabidopsis thaliana accessions from high altitude (Xizang, also known as "Tibet") and low altitude (Yunnan), respectively. The Xizang population represents a relict group characterized by a small effective population size. Notably, the Xizang genome has more transposable elements (TEs) and more gene loss-of-function (LoF) mutations. Differentially expressed genes were enriched in biological processes of cellular response to oxygen-containing compound, regulation of defense response, and response to light intensity. Intriguingly, the phenotypic selection analysis revealed that silique density was under natural selection. Furthermore, we genetically mapped and validated that the LoF mutation of GA20ox1, the homologous gene of green revolution in rice, resulted in a higher silique density in Xizang Arabidopsis. Given that GA20ox1 is linked to Arabidopsis adaptation to the Alps Mountains, its parallel evolution plays an important role in the adaptation to Alpine habitats. Overall, our results highlight that identifying adaptive traits and elucidating the molecular mechanisms underlying natural variation of these traits is crucial for unraveling the mystery of adaptive evolution and has significant implications for crop breeding.

The branched-chain amino acid-related isoleucic acid: recent research advances.

Isoleucic acid (ILA) was identified in human patients with maple syrup urine disease (MSUD) half a century ago. MSUD patients, who are defective in the catabolism of branched-chain amino acids (BCAAs), that is, isoleucine, leucine, and valine, have urine with a unique maple syrup odour related to the accumulation of BCAA breakdown products, largely 2-keto acid derivatives and their reduced 2-hydroxy acids including ILA. A decade ago, ILA was identified in Arabidopsis thaliana. Subsequent studies in other plant species indicated that ILA is a ubiquitously present compound. Since its identification in plants, several efforts have been made to understand the biological significance and metabolic pathway of ILA. ILA plays a positive role in plant signalling for defence responses against bacterial pathogens by increasing the abundance of salicylic acid aglycone through competitive inhibition of SA deactivation by glucosylation. Here, we review recent progress in the characterization of ILA biosynthesis and function in plants and discuss current knowledge gaps and future directions in ILA research.

Alginate oligosaccharide induces resistance against Penicillium expansum in pears by priming defense responses.

The research intended to explore the control ability of alginate oligosaccharide (AOS) on Penicillium expansum infection in pear fruit by priming response and its mechanism. The results showed that 100mgL-1 AOS treatment could significantly reduce the incidence of postharvest blue mold and the lesion diameter in pear fruits and maintain their quality. The defense responses induced by AOS treatment alone were relatively mild in pear fruits. Still, AOS-treated pear fruits inoculated with P. expansum showed more intense disease resistance responses. These defense responses included enhanced activities of chitinase (CHI), β-1, 3-glucanase (GLU), peroxidase (POD), polyphenol oxidase (PPO), phenylalanine ammonia-lyase activity (PAL), along with the accumulation of total phenolic compounds, flavonoids and lignin. Additionally, the expression levels of defense-related genes, such as PbGLU, PbCHI, PbPAL, PbPOD and PbPPO, were significantly upregulated. However, AOS did not show a potential inhibitory effect on the in vitro growth of P. expansum. Our results indicated that AOS treatment in the postharvest pear fruit enhances disease resistance by priming its defense responses.

A central role of stimulator of interferon genes' adaptor protein in defensive immune response.

Cytotoxic DNAs, methylation, histones and histones binding proteins are speculated to induce DNA sensors. Under stressed condition, the antigenic patterns, PAMPs and DAMPs, trigger the hyperactive innate response through DNA, DNA-RNA hybrids, oligonucleotides, histones and mtDNA to initiate cGAMP-STING-IFN I cascade. HSV -1&2, HIV, Varicella- Zoster virus, Polyomavirus, Cytomegalovirus, and KSHV negatively regulate the STING-MAVS-TBK-1/1KKE pathway. Implications in STING-PKR-ER regulation often run into causing senescence and organ fibrosis. Post-translational modifications such as, phosphorylation, ubiquitination, SUMOylation, hydrolysis etc. downstream the processing of cGAS-STING that determine the fate of disease prognosis. Self-DNA under normal circumstances is removed through DNase III action; however, its deficiency is the great cause of RA diseases. Regular STING activation in chronic diseases could lead to exacerbate the neurodegenerative disorders due to constant mtDNA leakage. 2' 3' cGAMP or CDN or its associates are being explored as STING agonist therapeutics to treat solid/metastatic tumors to help infiltrate the immune cells, cytokines and chemokines to regulate the protective response. Liposomes, polymer nanoparticles, and cell-derived nanoparticles are also meant to increase the drug efficiency and stability for desired immune response to enhance the IFN I production. This review highlights the implications of cGAMP-STING- IFN I cascade and related pathways involved in the disease prognosis, therapeutics and considering the gaps on different aspects to utilize its greater potential in disease control.

Differential activation of defense responses in cucumbers by adapted versus non-adapted lineages of the cotton-melon aphid.

The cotton-melon aphid, Aphis gossypii Glover, is a polyphagous pest damaging plants across over 100 families. It has multiple host-specialized lineages, including one colonizing Malvaceae (MA) and one colonizing Cucurbitaceae (CU). The mechanisms underlying these host relationships remain unknown. Here, we compared defensive compounds, gene expressions and aphid susceptibility of cucumbers (Cucumis sativus L.) that were infested with both lineages for up to 14 days. Total jasmonic acid (JA) remained constant in CU-infested cucumbers while increased to a maximum of 19.11 folds at 1 dpi (days post infestation) in MA-infested cucumbers. Total salicylic acid (SA) increased to a maximum of 4.42 folds at 7 dpi in MA-infested cucumbers while increased to a maximum of 2.83 folds at 14 dpi in CU-infested cucumbers. Reactive oxygen species were constantly higher in MA-infested cucumbers than CU-infested cucumbers at each time point. Genes involved in defense signaling, for example, MAPKs, PR-1s, and WRKY, and genes involved in JA and SA biosynthesis, were largely up-regulated in MA-infested cucumbers compared with CU-infested ones. Both lineages exhibited more stylet probing, less phloem ingestion, higher mortality, and less reproduction on MA-infested cucumbers compared with CU-infested ones. MA lineage aphids elicited stronger defenses in cucumbers than the CU lineage aphids. A lack of salivary effectors specific to cucumbers most likely prevents MA lineage aphids from using cucumbers. Identifying lineage-specific elicitors or effectors is therefore expected to unveil the molecular mechanisms of host specificity of this aphid. © 2025 Society of Chemical Industry.

XopAE Effector from Xanthomonas phaseoli pv. manihotis Targets HSP20-Like p23 Cochaperone to Suppress Plant Basal Immunity.

Pathogenic bacteria use Type 3 effector proteins to manipulate host defenses and alter metabolism to favor their survival and spread. The non-model bacterial pathogen Xanthomonas phaseoli pv. manihotis (Xpm) causes devastating disease in cassava. The molecular role of Type 3 effector proteins from Xpm in causing disease is largely unknown. Here, we report that the XopAE effector from Xpm suppresses plant defense responses. Our results showed that XopAE is a suppressor of basal defenses such as callose deposition and the production of reactive oxygen species (ROS). XopAE targets a small heat shock protein (Mep23-1 cochaperone) in cassava and its homolog Atp23-1 in Arabidopsis. XopAE localizes to the nucleus and in scattered points throughout the cell border, while Mep23-1 shows a nucleocytoplasmic localization. Upon interaction, XopAE hijacks Mep23-1 to the scattered points throughout the cell border and they also interact in nucleus. Our results indicate that the interaction between XopAE and Mep23-1 is essential for suppressing basal plant defense. This study is one of the first to address the molecular mechanisms deployed by Xpm to cause disease in cassava, a non-model crop plant.