Oxysterol-binding protein (OSBP)-related proteins (ORPs) are indispensable eukaryotic lipid transporters and promising targets for pharmaceutical and agrochemical exploitation. Among ORP family members across kingdoms, oomycete ORP1 constitutes a phylogenetically distinct subtype that evolved independently in oomycetes, which is markedly divergent from ORP homologues in animals, plants and fungi. Oxathiapiprolin, the first commercial fungicide targeting OSBP family proteins, specifically acts on oomycete ORP1 and exhibits robust inhibitory efficacy against diverse Phytophthora pathogens and downy mildews. Nevertheless, the molecular function of oomycete ORP1 and the inhibitory mechanism of oxathiapiprolin remain poorly defined. Here, we demonstrate that PsORP1 of Phytophthora sojae specifically localises to ER-Golgi membrane contact sites (MCSs) and is indispensable for vegetative growth and asexual/sexual development of P. sojae. In vitro liposome reconstitution assays confirmed that the conserved C-terminal OSBP-related domain (ORD) of PsORP1 mediates canonical phosphatidylserine (PS)/phosphatidylinositol 4-phosphate (PI4P) counter-transport. Biochemical binding assays further verified that oxathiapiprolin directly interacts with the ORD of PsORP1 and competitively blocks PS/PI4P lipid exchange. Collectively, this study demonstrates that PsORP1 localises to ER-Golgi MCSs and mediates ORD-dependent PS/PI4P counter-transport, which is essential for P. sojae development, and elucidates that oxathiapiprolin directly targets the ORD to competitively block this lipid exchange, providing a structural framework for rational design of next-generation OSBP-targeting inhibitors against oomycetes.
Colletotrichum asianum, the cause of mango anthracnose, is a major threat to mango production worldwide. However, the mechanisms underlying plant invasion by C. asianum are poorly understood. Mini-chromosomes are increasingly recognised as indispensable components in the virulence of plant-pathogenic fungi. Here, we identify CaMutA, a secreted glycoside hydrolase 71 effector encoded on a mini-chromosome, as a critical pathogenicity factor that suppresses plant immune responses and is essential for infection by C. asianum. CaMutA directly interacts with the mango chitinase MiChi1. When heterologously expressed in Arabidopsis thaliana, MiChi1 confers enhanced resistance against multiple pathogens, suggesting its role in plant defence, a process that CaMutA subverts. Together, our findings uncover that a mini-chromosome-encoded effector can subvert plant immunity by directing the ubiquitin-mediated degradation of conserved defence-related chitinases. This study thus identifies promising targets for controlling mango anthracnose.
Response regulators (RRs) of two-component signalling systems (TCSs) containing tandem receiver (REC) domains are widespread in bacteria, yet their functions and regulatory mechanisms remain poorly understood. In our previous study, DrdR, one such RR in the cruciferous black rot disease pathogen Xanthomonas campestris pv. campestris (Xcc) was demonstrated to positively regulate pilus-dependent motility and negatively regulate flagellum-dependent motility. We showed that DrdR modulates the ATPase activities of pili motor proteins PilT and PilB, thereby enhancing bacterial pilus-dependent swarming motility. However, how DrdR represses flagellar motility remained unknown. Here, we demonstrate that DrdR acts as a transcriptional repressor of flagellar gene expression. We used in vitro and in vivo approaches to identify FleQ, the master transcriptional regulator of flagellar genes, as a novel interaction partner of DrdR. Biochemical analyses revealed that DrdR binding inhibits FleQ's ATPase activity, which is essential for its transcriptional activation function. Microscale thermophoresis assays showed that DrdR reduces FleQ's DNA-binding capability to its cognate promoter. These findings collectively indicate that DrdR modulates FleQ transcriptional activity by reducing both its DNA-binding ability and ATPase activity. Our results demonstrate that DrdR serves as a specialized modulator of FleQ that acts upstream in the signalling cascade controlling the expression of flagellar genes in Xcc. This study exhibits a previously unknown mechanism whereby DrdR regulates bacterial motility. Combined with our previous finding, our data suggest that DrdR most likely acts as a conversion regulator between flagellum-dependent and pilus-dependent motility in Xcc.
Plant fungal pathogens secrete a plethora of effectors into host cells to facilitate their infection by interfering with the normal physiological processes of the host plant. However, the role of guanyl-specific ribonuclease T1 effector protein in the virulence of fungal pathogens remains largely unexplored. Here, we show that an effector protein EC19, secreted by the soil-borne fungus Fusarium oxysporum f. sp. lycopersici (Fol) that causes tomato wilt disease, contributes to the full virulence of Fol. In-locus knockout of EC19 significantly reduced the virulence of Fol, while complementing EC19 in the knockout mutant restored the pathogenicity of Fol on tomato. EC19, which contains the ribonuclease T1-like domain, is highly conserved across fungal species and exhibited the ability to cleave single-stranded RNA isolated from tomato. EC19 was specifically induced during Fol infection. The AlphaFold3-predicted structure of EC19 shows a high degree of structural similarity with ribonuclease T1 from Aspergillus oryzae, with limited similarity to RNase T2. Using Agrobacterium-mediated transient assay in the leaves of Nicotiana benthamiana, we found that EC19 predominantly localised to the nucleus of plant cells. Stable transgenic susceptible tomato plants overexpressing EC19 exhibited increased susceptibility to Fol infection compared to wild-type plants. RNA-seq analysis of EC19-overexpressing tomato lines revealed that downregulated differentially expressed genes were predominantly enriched in plant hormone signal transduction, phenylpropanoid biosynthesis, and plant-pathogen interaction pathways. Taken together, these findings indicate that EC19 with ribonuclease activity promotes Fol infection, expanding our understanding of the molecular mechanisms underlying Fol virulence.
Geminiviruses severely threaten global crop production. Tomato yellow leaf curl virus (TYLCV) encodes multifunctional effector C4, which participates in diverse biological processes and interacts with host proteins to facilitate infection. Despite extensive studies on geminiviral C4, how TYLCV C4 suppresses tomato immunity remains poorly characterized. In this study, we identified the tomato 14-3-3 protein SlTFT2 as a specific interaction partner of the TYLCV C4 protein. We demonstrated that SlTFT2 functions as a positive regulator of antiviral defence, as its silencing enhanced systemic viral infection, whereas its overexpression restricted infection. A critical serine residue at position 86 in C4 was essential for this interaction, and mutation of this residue (S86A or S86L) in TYLCV infectious clones significantly attenuated viral infectivity. Furthermore, C4, but not the S86A or S86L mutants, reduced the nuclear accumulation of SlTFT2. Collectively, our findings establish that the C4-SlTFT2 interaction is indispensable for TYLCV-mediated immunosuppression. Moreover, C4 promotes successful TYLCV infection by reducing the nuclear accumulation of SlTFT2 through this interaction, revealing a novel mechanism by which the virus subverts host defence by targeting a 14-3-3 protein.
Successful infection by plant-pathogenic fungi requires both penetration of the host cuticle and tolerance of the reactive oxygen species (ROS) burst associated with host immunity. However, how these early infection events are temporally coordinated remains unclear. Here, we identified a three-tier transcriptional cascade, ApHSF-ApCtf1β2-ApCUT3, in Arthrinium phaeospermum, the causal agent of shoot blight in hybrid bamboo (Bambusa pervariabilis × grandis). Yeast one-hybrid, electrophoretic mobility shift and dual-luciferase assays showed that ApHSF directly binds the CTAGAA core motif in the ApCtf1β2 promoter and activates its transcription. Functional analyses further showed that ApHSF promotes detoxification of host-derived ROS by activating the fungal antioxidant system, whereas pharmacological suppression of host ROS accumulation substantially restored the pathogenicity defect of the ΔApHSF mutant. ApHSF neither bound nor independently activated the ApCUT3 promoter. Instead, yeast three-hybrid and combinatorial dual-luciferase assays showed that, under early oxidative stress, ApHSF acts as a cofactor to enhance ApCtf1β2-dependent activation of ApCUT3. In vivo fluorescence imaging further demonstrated that ROS detoxification alone was insufficient for full pathogenicity, which additionally required an intact ApCtf1β2-ApCUT3 module for cuticle penetration and colonization. Phos-tag immunoblotting, λ-protein phosphatase treatment and kinase inhibition assays showed that heat and oxidative stress induced phosphorylation of ApHSF and ApCtf1β2 and that these phosphorylation responses depended on p38 MAPK activity. By contrast, host cuticle-derived cues preferentially induced the ApCtf1β2-ApCUT3 module. Together, these findings reveal how a plant-pathogenic fungus integrates oxidative and cuticle-associated signals to coordinate early infection.
Small G-proteins are crucial regulators in plant growth and environmental responses. However, the mechanistic basis underlying their regulation of plant immunity to different pathogens is still poorly understood. Here, we showed that the small GTPase Ras homologous 1 (RHO1) responded differently to infection by distinct pathogens. Overexpression of RHO1 increased the plant susceptibility to chilli veinal mottle virus (ChiVMV) and necrotrophic Botrytis cinerea infections but enhanced plant resistance to the biotrophic bacterium Pseudomonas syringae. Further exploration revealed that there existed a direct interaction between RHO1 and tonoplast intrinsic protein 1;1 (TIP1;1), an aquaporin involved in water movement and the transport of hydrogen peroxide (H2O2) between vacuoles and cytoplasm. Under pathogen infection, the interaction between RHO1 and TIP1;1 could affect the distribution of reactive oxygen species (ROS) in the cytoplasm and vacuoles, promote the accumulation of ROS in the cytoplasm, leading to different responses of plant cells to pathogens with different lifestyles. Furthermore, the expression level of TIP1;1 was altered under infection by different pathogens. Our results demonstrate a mechanism by which the small GTPase RHO1 regulates ROS compartmentalization to affect the plant response to different pathogen infections, indicating the diversity of responses of a plant gene to different biotic factors.
Powdery mildew disease (PMD), caused by Microsphaera diffusa, is a devastating soybean foliar disease. This study identified GmRmd1 as a candidate in Guangxi landrace MSRF (all-stage resistance to PMD) and validated it as a positive PMD resistance regulator. Hypersensitive response (HR) assays confirmed its Toll interleukin-1 receptor (TIR), nucleotide-binding site (NBS) and basic secretory protein (BSP) domains are critical for immune responses. GmRmd1 was induced by M. diffusa, and its expression was inhibited by GmWRKY27 and GmERF138 specifically binding to the W-box and GCC-box elements of the GmRmd1 promoter, respectively. RNA-Seq revealed that chromosome 16 (chr16) resistance cluster genes (Glyma.16G214100, Glyma.16G214200, Glyma.16G215100 and Glyma.16G215800) showed GmRmd1-related expression patterns. Yeast two-hybrid, bimolecular fluorescence complementation and luciferase assays demonstrated GmRmd1 interacts not only with itself, but also with GmRmd2 (Glyma.16G215100), GmRmd3 (Glyma.16G214900) and GmRnl1 (NLR cofactor). In addition, mutants of GmRmd3 and GmRnl1 are more susceptible to M. diffusa. Notably, GmRmd1 enhances the resistance of PMD by interacting with GmPER1 (lignin synthesis-related) and increasing the synthesis of lignin. Genomic analysis indicated that the number of soybean accessions carrying the GmRmd1 locus gradually decreases from north to south and from west to east in China. Taken together, GmRmd1 forms functional protein complexes with GmRmd2, GmRmd3, and GmRnl1 to regulate lignin biosynthesis and thereby modulate disease resistance. These insights provide novel perspectives into the molecular mechanisms of GmRmd1-mediated resistance to soybean PMD.
Xanthomonas oryzae pv. oryzicola (Xoc), the causal agent of bacterial leaf streak of rice, relies on a functional type III secretion system (T3SS) for full virulence and for induction of the hypersensitive response (HR) in nonhost plants. Although the HrpG-HrpX regulatory cascade is central to T3SS gene expression in Xanthomonas, the upstream regulatory mechanisms controlling this pathway in Xoc remain insufficiently understood. In the present study, we identified GpaR as a previously unrecognised transcriptional activator required for T3SS-associated pathogenicity in Xoc. Deletion of gpaR significantly attenuated virulence in rice and resulted in delayed and weakened HR in Nicotiana benthamiana. Reverse transcription-quantitative PCR analysis showed that transcript levels of hrpG, hrpX, and multiple T3SS-associated hrp genes were markedly reduced in the ΔgpaR mutant. Consistent with these results, β-glucuronidase (GUS) reporter assays demonstrated that promoter activities of hrpG and hrpX were substantially decreased in the absence of GpaR. Furthermore, constitutive expression of hrpG or hrpX in the ΔgpaR background largely restored virulence and HR, indicating that these regulators function downstream of GpaR. Electrophoretic mobility shift assays (EMSA) and chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) demonstrated that GpaR binds directly to the promoter regions of hrpG and hrpX in vitro and associates with them in vivo. In addition, in vitro transcription assays showed that GpaR directly activates transcription from both promoters. Collectively, these findings establish GpaR as a direct upstream activator of the HrpG-HrpX cascade and identify a new regulatory layer controlling T3SS expression and virulence in Xoc.
Calcium ion (Ca2+) signalling is crucial for multiple biological processes in fungi, including growth, stress adaptation and pathogenic behaviour. The vacuolar Ca2+/H+ exchanger (VCX) is vital for maintaining calcium homeostasis within fungal cells, yet its specific biological functions in phytopathogenic fungi remain poorly understood. This study focused on the role and transcriptional regulation of AaVCX in Alternaria alternata, the organism responsible for pear black spot disease. By employing a split-marker strategy, we generated AaVCX knockout (ΔAaVCX) and complemented (ΔAaVCX-C) strains. Phenotypic assessments revealed that ΔAaVCX exhibited reduced mycelial growth, abnormal accumulation of intracellular Ca2+ and heightened sensitivity to various stressors. Deletion of AaVCX severely hindered spore germination, differentiation of appressoria and invasive hyphae in A. alternata triggered by pear peel wax. The ΔAaVCX nearly lost its ability to penetrate cellophane, and its virulence on pear fruits and leaves was markedly diminished. Molecular docking analysis indicated that AaCrz1, a key transcription factor in the calcium signalling pathway, can bind to the promoter of AaVCX. Dual-luciferase and yeast one-hybrid assays demonstrated that AaCrz1 binds to the AaVCX promoter in vitro and positively regulates its expression, with a predicted GCC-core motif identified in the promoter region. Furthermore, transcript levels of AaVCX were significantly reduced in the ΔAaCrz1 background, indicating that AaVCX is positioned downstream of AaCrz1 in a regulatory cascade. Our findings enhance the understanding of calcium signalling networks in phytopathogenic fungi and propose that components involved in vacuolar calcium storage may serve as potential targets for disease management.
Bacterial pathogens of woody plants represent a pervasive yet underexplored threat to global agriculture and forestry, causing devastating diseases in fruit trees, shrubs, forest trees and ornamental species. Unlike pathogens of herbaceous plants, the molecular strategies enabling bacteria to colonise and damage woody tissues remain poorly understood, owing to the experimental challenges associated with woody host systems and the distinctive biology of these plants. Moreover, persistence within long-lived woody tissues requires prolonged modulation of host immune signalling, enabling pathogens to evade or attenuate defence responses across growing seasons. This review synthesises current knowledge of the virulence mechanisms underlying bacterial infection of woody hosts, highlighting host-specific strategies and conserved pathways critical for disease establishment. Key mechanisms include manipulation of plant immune responses through type III secretion system effectors and other secreted proteins, catabolism of host-derived metabolites, degradation of structural barriers, and the activity of bacterial toxins and extracellular polysaccharides. By integrating these molecular insights, we examine how bacterial pathogens have evolved adaptive strategies to overcome the unique challenges posed by woody tissues and emphasise the implications for disease management in economically important crops. Addressing knowledge gaps in woody-host infections is essential for developing innovative, targeted strategies to mitigate the impact of these pathogens and safeguard global woody crops and forestry systems.
Fusarium graminearum causes Fusarium head blight (FHB), a devastating wheat disease that threatens global food security and safety. Nuclear Dbf2-related (NDR) kinases regulate cellular morphogenesis, but their roles in phytopathogenic fungi remain elusive. Here, we characterized F. graminearum NDR kinase FgCot1, whose deletion severely disrupted vegetative growth, conidiation, polarized growth and pathogenicity. Notably, the Fgcot1 mutant showed genetic instability, producing fast-growing suppressors with primary (Gpmk1 pathway genes), secondary (MFS transporter SSF1) and tertiary (transcription factor TSF1) mutations. Functional analyses revealed that disrupting the Gpmk1 pathway partially rescued the Fgcot1 growth defects due to Gpmk1 hyperactivation, whereas SSF1 deletion independently enhanced growth. The TSF1R386C mutation suppressed the Fgcot1 growth defect via a Gpmk1/Ssf1-independent pathway. Moreover, FST11 deletion and TSF1R386C mutation significantly alleviated the Fgcot1 mutant's polarized growth defect and slightly restored conidiation, suggesting that Gpmk1 and Tsf1 function in parallel pathways downstream of FgCot1 kinase. Finally, we demonstrated that FgCot1 interacts with Tsf1 and regulates its protein stability and nuclear accumulation; R386C mutation restored these defects of Tsf1 in the Fgcot1 mutant. Collectively, FgCot1 kinase integrates Gpmk1 signalling and Tsf1-dependent transcription to govern polarized growth and conidiation in F. graminearum.
Reactive oxygen species (ROS) serve as critical immune factors in plants, defending against pathogens infection, but whether pathogenic fungi respond to host-derived ROS through autophagy remains obscure. We previously found that CfSnt2-mediated H3 deacetylation regulates autophagy and responses to oxidative stress in Colletotrichum fructicola, a widespread pathogenic fungus that infects over 50 crops. However, the specific regulatory mechanism is unclear, particularly how oxidative stress is linked to autophagy. Here, we provided evidence that autophagy is highly induced during C. fructicola infection and oxidative stress. We further conducted mass spectrometry analysis of CfSnt2-interacting proteins and identified the histone deacetylase CfRpd3 for functional characterization. We found that CfRpd3 was primarily localized in the nucleus and cooperated with CfSnt2 to regulate the histone H3 deacetylation. Moreover, we demonstrated that both CfRpd3 and CfSnt2 are autophagy repressors that undergo down-regulated expression during ROS-induced autophagy. Targeted gene-deletion of CfRPD3 generated a ΔCfrpd3 mutant that showed defects in growth, conidiation, appressorial formation, and responses to oxidative stress, similar to those observed in the ΔCfsnt2 mutant. These combined effects resulted in their pathogenicity defects. Taken together, our study illustrates a new mechanism by which the CfSnt2-CfRpd3-mediated H3 deacetylation precisely coordinates with autophagy to regulate ROS response and pathogenicity in C. fructicola.
Wheat leaf rust, caused by Puccinia triticina, is a widespread economically important wheat disease. During infection, P. triticina secretes effectors proteins to manipulate host immunity. Here we identified and characterized the P. triticina effector Pt3863, which is highly expressed during the early phase of infection and significantly enhances fungal virulence. We also identified the wheat receptor-like cytoplasmic kinase TaRLCK176 as a target of Pt3863. Functional assays demonstrated that TaRLCK176 positively regulates wheat resistance against leaf rust and is required for chitin-induced reactive oxygen species (ROS) accumulation. Pt3863 subverts this defence through a dual inhibitory mechanism: first, it suppresses TaRLCK176 phosphorylation; second, it promotes TaRLCK176 degradation via the ubiquitin-26S proteasome pathway. Host-induced gene silencing Pt3863 attenuated P. triticina virulence, while its overexpression in transgenic wheat lines increased susceptibility to P. tritici. Conversely, virus-induced gene silencing of TaRLCK176 compromised wheat resistance. Our findings establish TaRLCK176 as a critical immune hub that positively modulates wheat resistance to leaf rust and is specifically targeted by the P. triticina effector Pt3863. Notably, Pt3863 has evolved a sophisticated virulence strategy to simultaneously disrupt both the phosphorylation-mediated activation and proteasomal stability of TaRLCK176, thereby impairing host immune responses. This study elucidates a key molecular mechanism underlying the suppression of wheat immunity by P. triticina and highlights TaRLCK176 as a promising candidate target for the genetic engineering of durable resistance in wheat against leaf rust.
Rice is a staple crop primarily recognised for its high content of carbohydrates and proteins. Rice yellow mottle disease (RYMD) is a destructive disease affecting rice fields in sub-Saharan Africa and is caused by the rice yellow mottle virus (RYMV). Development of virus-resistant genotypes is a highly recommended and effective approach to controlling RYMV. A genetic approach that exploits recessive mutations in susceptibility (S) genes may enhance resistance to the virus. Reports indicate that most rice genotypes grown in Kenya are vulnerable to RYMV infection. Genome editing has shown promise in enhancing agronomic traits in crops. We obtained enhanced resistance to RYMV in the Indica rice cv. IR2793-80-01 using the CRISPR-Cas9 system. The eIF(iso)4G susceptibility gene was targeted because natural mutations in this gene confer recessive resistance to RYMV. A Cas9-OseIF(iso)4G-gRNA-expressing vector targeting the eIF(iso)4G gene was introduced into rice calli via Agrobacterium-mediated transformation. Ten T2 homozygous mutant plant lines were assessed for their reaction to RYMV, and infection was significantly reduced. There were no significant differences in the agronomic characteristics between the T2 mutant lines and the wild-type plants. CRISPR/Cas9-mediated knockout alleles of the eIF(iso)4G gene conferred enhanced resistance to RYMV, which may be classified as partial. Findings underscore the need to embrace precise editing strategies, such as prime editing, to generate superior resistance alleles. Overall, the study provides an alternative resistance enhancement strategy that can create knockout resistance alleles that can be incorporated into breeding programmes for RYMV resistance.
Late blight, caused by oomycete pathogen Phytophthora infestans, is one of the most devastating diseases of potato and tomato. Plant resistance to pathogens relies on a sophisticated innate immune system, which is often targeted by pathogen-derived effectors. P. infestans secretes numerous RXLR effectors to suppress host immunity. In this study, we show that the P. infestans core effector Pi05910 functions as a virulence factor and targets the host scaffold protein Receptor for Activated C Kinase 1 (RACK1), which is identified to positively regulate potato resistance to late blight. Functional analyses showed that StRACK1-silencing in potato, and tobacco rattle virus (TRV)-based virus-induced NbRACK1-silencing in Nicotiana benthamiana, consistently increased host susceptibility to P. infestans colonisation, whereas transient expression of NbRACK1 in N. benthamiana or stable overexpression of StRACK1 in potato enhanced late blight resistance. Pi05910 physically interacts with RACK1 and promotes its destabilisation via the host 26S proteasome pathway. The destabilisation of RACK1 led to the inhibition of PAMP elicitor INF1-triggered plant immune responses, including reactive oxygen species burst and expression of defence-related genes such as StWRKY7 and StWRKY8, and suppression of potato and N. benthamiana growth and global protein translation. Our findings reveal a strategy whereby a pathogen effector sabotages a key potato immune scaffold StRACK1 to promote plant susceptibility to P. infestans infection, providing new insight into mechanisms of effector-triggered plant susceptibility.
Mitogen-activated protein kinase (MAPK) cascades have been extensively reported to be involved in biotic and abiotic stress processes by regulating hydrogen peroxide (H2O2) homeostasis in plants. However, the detailed mechanisms by which MAPK cascades regulate H2O2 homeostasis in response to bacterial pathogens in rice remain largely unknown. Here, we demonstrate that rice CATALASE A (OsCATA) is a new substrate of OsMAPK6 and negatively regulates rice resistance to Xanthomonas oryzae pv. oryzae (Xoo) by directly suppressing H2O2 accumulation. Our results showed that OsMAPK6 interacts with OsCATA and specifically phosphorylates it at serine 460. The phosphorylation of OsCATA by OsMAPK6 attenuates OsCATA accumulation and reduces its catalase activity in vitro. The OsMAPK6-overexpressing (OsMAPK6-OE) plants showed lower catalase activity and higher accumulation of H2O2 compared with wild-type plants. The oscata mutant plants generated by the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) strategy showed higher accumulation of H2O2 and increased resistance to Xoo. Together, these results suggest that the OsMAPK6-OsCATA module is involved in modulating rice H2O2 homeostasis and immunity.
Fusarium sacchari, the causal agent of pokkah boeng disease (PBD), is a globally devastating pathogen of sugarcane that causes substantial economic losses. During infection, the fungus employs elicitors to induce necrosis in plant tissues, thereby enhancing pathogen fitness. However, the key elicitors in F. sacchari and the mechanism by which plants recognize them remain unclear. Here, we identified a predicted glycosylated phosphatidylinositol (GPI)-anchored protein FsEcm33 as an elicitor that activates plant immunity. FsEcm33 is perceived in the apoplast of Nicotiana benthamiana by the receptor-like protein NbRE02 and induces cell death in a manner that requires the co-receptors NbBAK1 and NbSOBIR1. Purified FsEcm33 triggers basal immune responses in N. benthamiana and enhances disease resistance in multiple plant species, including sugarcane, rice, wheat, and star anise. In F. sacchari, FsEcm33 localizes to the cell surface, where its recognition by the host limits pathogen colonization. Notably, FsEcm33 specifically interacts with a 14-3-3 protein, FsBmh1, which reduces its accumulation at the fungal cell surface, suggesting a spatial sequestration mechanism that helps F. sacchari evade host immunity. Together, these findings establish FsEcm33 as a cell-surface elicitor perceived by NbRE02 and reveal an evolutionary strategy in which FsBmh1 sequesters FsEcm33 to evade host recognition and facilitate infection in F. sacchari.
