Induce Plant Defense Responses Research Articles

Algae and Their Metabolites as Potential Bio-Pesticides.

An increasing human population necessitates more food production, yet current techniques in agriculture, such as chemical pesticide use, have negative impacts on the ecosystems and strong public opposition. Alternatives to synthetic pesticides should be safe for humans, the environment, and be sustainable. Extremely diverse ecological niches and millions of years of competition have shaped the genomes of algae to produce a myriad of substances that may serve humans in various biotechnological areas. Among the thousands of described algal species, only a small number have been investigated for valuable metabolites, yet these revealed the potential of algal metabolites as bio-pesticides. This review focuses on macroalgae and microalgae (including cyanobacteria) and their extracts or purified compounds, that have proven to be effective antibacterial, antiviral, antifungal, nematocides, insecticides, herbicides, and plant growth stimulants. Moreover, the mechanisms of action of the majority of these metabolites against plant pests are thoroughly discussed. The available information demonstrated herbicidal activities via inhibition of photosynthesis, antimicrobial activities via induction of plant defense responses, inhibition of quorum sensing and blocking virus entry, and insecticidal activities via neurotoxicity. The discovery of antimetabolites also seems to hold great potential as one recent example showed antimicrobial and herbicidal properties. Algae, especially microalgae, represent a vast untapped resource for discovering novel and safe biopesticide compounds.

Активность гидролаз в листьях картофеля при обработке ризобактериями и индукторами устойчивости в условиях заражения фитофторой и недостатка влагообеспечения

Changes in the activity of amylases, proteases, and cellulases in the leaves of potato plants grown under late blight infection and deficiency of soil moisture under the influence of pretreatment with Bacillus subtilis bacteria, salicylic acid (SA), jasmonic acid (JA), and their mixture were studied. In plants treated with B. subtilis in combination with signal molecules, higher amylolytic and proteolytic activity was observed, this effect was especially pronounced when treated with B. subtilis in combination with both signal molecules. Treatment of plants with bacteria together with SA and JA, which activates a whole complex of signaling pathways, can be considered as a potential way to induce plant defense responses to increase resistance to pathogen attack.

A glutamate synthase mutant of Bradyrhizobium sp. strain ORS285 is unable to induce nodules on Nod factor-independent Aeschynomene species

The Bradyrhizobium sp. strain ORS285 is able to establish a nitrogen-fixing symbiosis with both Nod factor (NF) dependent and NF-independent Aeschynomene species. Here, we have studied the growth characteristics and symbiotic interaction of a glutamate synthase (GOGAT; gltD::Tn5) mutant of Bradyrhizobium ORS285. We show that the ORS285 gltD::Tn5 mutant is unable to use ammonium, nitrate and many amino acids as nitrogen source for growth and is unable to fix nitrogen under free-living conditions. Moreover, on several nitrogen sources, the growth rate of the gltB::Tn5 mutant was faster and/or the production of the carotenoid spirilloxanthin was much higher as compared to the wild-type strain. The absence of GOGAT activity has a drastic impact on the symbiotic interaction with NF-independent Aeschynomene species. With these species, inoculation with the ORS285 gltD::Tn5 mutant does not result in the formation of nodules. In contrast, the ORS285 gltD::Tn5 mutant is capable to induce nodules on NF-dependent Aeschynomene species, but these nodules were ineffective for nitrogen fixation. Interestingly, in NF-dependent and NF-independent Aeschynomene species inoculation with the ORS285 gltD::Tn5 mutant results in browning of the plant tissue at the site of the infection suggesting that the mutant bacteria induce plant defence responses.

Foliar Application or Seed Priming of Cholic Acid-Glycine Conjugates can Mitigate/Prevent the Rice Bacterial Leaf Blight Disease via Activating Plant Defense Genes.

Xanthomonas Oryzae pv. oryzae (Xoo) causes bacterial blight and Rhizoctonia solani (R. solani) causes sheath blight in rice accounting for >75% of crop losses. Therefore, there is an urgent need to develop strategies for the mitigation of these pathogen infections. In this study, we report the antimicrobial efficacy of Cholic Acid-Glycine Conjugates (CAGCs) against Xoo and R. solani. We show that CAGC C6 is a broad-spectrum antimicrobial and is also able to degrade biofilms. The application of C6 did not hamper plant growth and showed minimal effect on the plant cell membranes. Exogenous application of C6 on pre-infection or post-infection of Xoo on rice susceptible genotype Taichung native (TN1) can mitigate the bacterial load and improve resistance through upregulation of plant defense genes. We further demonstrate that C6 can induce plant defense responses when seeds were primed with C6 CAGC. Therefore, this study demonstrates the potential of CAGCs as effective antimicrobials for crop protection that can be further explored for field applications.

Isolation and identification of Amycolatopsis sp. strain 1119 with potential to improve cucumber fruit yield and induce plant defense responses in commercial greenhouse

The application of chemical fungicides is the first strategy to control plant fungal diseases. This approach is highly polluting for the environment and affects human health. The artificial introduction of beneficial rhizobacteria into the soil can be an economical and practical way to control phytopathogenic fungi in commercial greenhouses. Here, we recount the travel of a rare Actinomycete (Amycolatopsis strain 1119) from a maize field to a commercial cucumber greenhouse. Culturable bacteria from rhizosphere and bulk soils of dicot and monocot crops were isolated and screened. About 20% of the representative colonies showed Actinobacteria appearance. 106 Actinobacteria that had antagonistic activity against Phytophthora capsici and were able to produce IAA-like molecules were selected for further analysis. Two Streptomyces strains (432 and 615) and 2 Amycolatopsis strains (3513 and 1119) that showed a positive effect on plant growth in greenhouse conditions were selected to evaluate the biocontrol potential. Strains 432, 3513, 615 and 1119 controlled incidence of the damping-off by 65%, 42%, 83% and 100% respectively. Application of strain 1119 under commercial greenhouse conditions resulted in an increase in fruit yield (20%) and a decrease in fruit nitrate content (70%). Increased antioxidant enzymes activity and increased LOX and APX transcription and also, increased expression of two genes PR1-1a and GLU (SAR genes) showed that strain 1119 could induce both ISR and SAR in cucumber without pathogen exposure. Our results demonstrate that the Amycolatopsis strain 1119 has a great potential to be used as an active principle for bio-inoculant development because of the ability to improve cucumber fruit yield and induce plant defense responses in a commercial greenhouse.

Greenhouse and field experiments revealed that clove oil can effectively reduce bacterial blight and increase yield in pomegranate

AbstractBacterial blight in pomegranate is a devastating disease caused by bacterial pathogen Xanthomonas axonopodis pv. punicae (XAP), recording huge damage to pomegranate crop worldwide. Antibiotics and copper‐based chemicals are being used for the management of this blight, while in this present work, we investigated the effect of eugenol and clove oil either singly or in combination with copper oxychloride (COC) on the induction of plant defense responses and concomitant prevention of bacterial blight. Our results provided evidence that clove oil (0.2%–1%) and eugenol (0.1% and 0.2%) successfully inhibit the growth of XAP in paper disk diffusion assay. Strikingly under the greenhouse condition, clove oil (0.2%) as foliar application 24 h before XAP inoculation recorded the lowest disease severity of 7.34%, whereas eugenol (0.2%) recorded maximum disease severity of 14.56%. However, the combination of clove oil (0.2%) and copper oxychloride (0.3%) recorded the least disease severity of 2.38%. A similar trend was observed in field conditions. Prophylactic application of clove oil leads to enhanced nitrate reductase activity and nitric oxide production which was further enhanced in clove oil pre‐treated plants challenged with XAP. Strikingly, the total ROS and H2O2 levels were reduced in response to clove oil application. Clove oil also induced the systemic response by inducing expression levels of defense genes. The reduction of disease severity by clove oil and COC combination also reflected on total yield recording via large‐scale field experiments where maximum yield of 14.04 tonnes/acre was observed, whereas streptocycline application recorded 11.12 tonnes/acre. Application of COC and clove oil resulted in a high remunerative value of ₹ 1:5.6, compared to streptocycline (1:4.85) and control (1:1.85). The present study revealed that clove oil as a plant derivative and eugenol as a synthetic option can be effectively used for the successful management of bacterial blight in pomegranate.

Methyl jasmonate‐induced resistance to Delia platura (Diptera: Anthomyiidae) in Lupinus mutabilis

Andean lupin (Lupinus mutabilis Sweet) is an important leguminous crop from South America with a high protein content. In Ecuador, lupin yields are severely affected by the infestation of Delia platura larvae on germinating seeds. The application of elicitor molecules with activity against herbivorous insects to control D. platura infestation constitutes an unexplored and promising alternative for chemical insecticides. In this study, methyl jasmonate (MeJA), hexanoic acid, menadione sodium bisulfite, and DL-β-aminobutyric acid were evaluated for their ability to induce resistance against D. platura in three commercial lupin cultivars. Only seeds pretreated with MeJA significantly impaired insect performance during choice and no-choice assays. Additionally, fitness indicators such as seed germination and growth were not affected by MeJA treatment. To investigate the molecular mechanisms behind the MeJA-mediated resistance, RT-qPCR assays were performed. First, RT-qPCR reference genes were validated, showing that LmUBC was the most stable reference gene. Next, expression analysis over time revealed that MeJA application up-regulated the activity of the jasmonic acid biosynthetic genes LmLOX2 and LmAOS, together with other jasmonate-related defense genes, such as LmTPS1, LmTPS4, LmPI2, LmMBL, LmL/ODC, LmCSD1, and LmPOD. This study indicates that MeJA can be used as an environmentally friendly elicitor molecule to protect Andean lupin from D. platura attack without fitness cost. MeJA application induces plant defense responses to insects in Andean lupin that may be modulated by the onset of terpenoid biosynthesis, proteinase inhibitors, lectins, polyamines, and antioxidative enzymes. © 2021 Society of Chemical Industry.

Identification of Riptortuspedestris Salivary Proteins and Their Roles in Inducing Plant Defenses.

Simple SummaryThe bean bug, Riptortus pedestris (Fabricius) is a notorious pest of soybean crops in Asia. During the feeding process, the bug secretes a mixture of salivary components, which play critical roles in the insect–plant interactions. In the present study, a total of 136 salivary proteins were identified by transcriptomic and proteomic approaches. Among them, five proteins (RpSP10.3, RpSP13.4, RpSP13.8, RpSP17.8, and RpSP10.2) were capable of inducing cell death, reactive oxygen species (ROS) burst, and hormone signal changes, indicating the potential roles of these proteins in eliciting plant defenses. Our results provide a good resource for future functional studies of bug salivary effectors and might be useful in pest management.The bean bug, Riptortus pedestris (Fabricius), is one of the most important soybean pests. It damages soybean leaves and pods with its piercing-sucking mouthparts, causing staygreen-like syndromes in the infested crops. During the feeding process, R. pedestris secretes a mixture of salivary proteins, which play critical roles in the insect–plant interactions and may be responsible for staygreen-like syndromes. The present study aimed to identify the major salivary proteins in R. pedestris saliva by transcriptomic and proteomic approaches, and to screen the proteins that potentially induced plant defense responses. Altogether, 136 salivary proteins were identified, and a majority of them were involved in hydrolase and binding. Additionally, R. pedestris saliva contained abundant bug-specific proteins with unknown function. Transient expression of salivary proteins in Nicotiana benthamiana leaves identified that RpSP10.3, RpSP13.4, RpSP13.8, RpSP17.8, and RpSP10.2 were capable of inducing cell death, reactive oxygen species (ROS) burst, and hormone signal changes, indicating the potential roles of these proteins in eliciting plant defenses. Our results will shed more light on the molecular mechanisms underlying the plant–insect interactions and are useful for pest management.

A Small Cysteine-Rich Phytotoxic Protein of Phytophthora capsici Functions as Both Plant Defense Elicitor and Virulence Factor.

Small cysteine-rich (SCR) proteins, including fungal avirulence proteins, play important roles in pathogen-plant interactions. SCR protein-encoding genes have been discovered in the genomes of Phytophthora pathogens but their functions during pathogenesis remain obscure. Here, we report the characterization of one Phytophthora capsici SCR protein (namely, SCR82) with similarity to Phytophthora cactorum phytotoxic protein PcF. The scr82 gene has 10 allelic sequences in the P. capsici population. Homologs of SCR82 were not identified in fungi or other organisms but in Phytophthora relative species. Initially, scr82 was weakly expressed during the mycelium, sporangium, and zoospore stages but quickly upregulated when the infection initiated. Both ectopic expression of SCR82 and recombinant yeast-expressed protein (rSCR82) caused cell death on tomato leaves. Upon treatment, rSCR82 induced plant defense responses, including the induction of defense gene expression, reactive oxygen species burst, and callose deposition. Knockout of scr82 in P. capsici by CRISPR/Cas9 severely impaired its virulence on host plants and significantly reduced its resistance against oxidative stress. Inversely, its overexpression increased the pathogen's virulence and tolerance to oxidative stress. Our results collectively demonstrate that SCR82 functions as both an important virulence factor and plant defense elicitor, which is conserved across Phytophthora spp.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Protection of tomato plants against Fusarium oxysporum f. sp. lycopersici induced by chitosan

Physiological processes of plants infected by vascular pathogens are mainly affected by vascular bundle obstruction, decreasing the absorption of water and nutrients and gas exchange by stomatal closure, and inducing oxidative cascades and PSII alterations. Chitosan, a derivative of chitin present in the cell wall of some organisms including fungi, induces plant defense responses, activating systemic resistance. In this study, three chitosan molecules (low, medium and high molecular weight) at different concentrations (0.5, 1, 1.5, 2, 2.5 and 3 mg mL-1) were assessed by in vitro tests against Fusarium oxysporum f. sp. lycopersici (Fol). Concentrations higher than 1 mg mL-1 were found to inhibit significantly the mycelial growth of Fol, with 95.8% of inhibition using chitosan with high molecular weight (3 mg mL-1). For in planta assays, chitosan treatment (low molecular weight 2.5 mg mL-1) showed significantly lower incidence and severity of wilting disease symptoms, 70 and 91%, respectively, compared to healthy plants used as a negative control. The effect of chitosan on the physiological and molecular responses of tomato plants infected with Fol was studied, evaluating the maximum potential quantum efficiency of PSII photochemistry (Fv/Fm), photochemical efficiency of PSII (Y(II)), stomatal conductance (gs), relative water content (RWC), proline content, photosynthetic pigments, dry mass, and differential gene expression (PAL, LOXA, ERF1, and PR1) of defense markers. A reduction of 70% in the incidence and 91% in the severity of the disease was achieved in plants treated with chitosan, mitigating the damage caused by Fol on Fv/Fm, Y(II), and chlorophyll contents by 23, 36, and 47%, respectively. Less impact was observed on gs, RWC, and dry mass (55, 11, and 26%, respectively). Chitosan-treated and Fol-infected plants over-expressed PR1a gene suggesting a priming-associated response. These results demonstrate the high potential of chitosan to protect tomato plants against Fol by regulating physiological and molecular responses in tomato plants.

Electrical Stimulation Enhances Plant Defense Response in Grapevine through Salicylic Acid-Dependent Defense Pathway.

Concern over environmental pollution generated by chemical fungicides has led to the introduction of alternative pest management strategies to chemical fungicide application. One of those strategies is the induction of plant defense response by an abiotic elicitor. In the present study, field-grown grapevines were subjected to electrical stimulation using a solar panel from two weeks before flowering to harvest in the 2016 and 2020 growing seasons. In both years, electrical stimulation decreased the incidence of gray mold and/or ripe rot on bunches and downy mildew on leaves of the field-grown grapevine. Transcription of a gene encoding β-1,3-glucanase but not class IV chitinase in leaves of potted grapevine seedlings was upregulated 20 days after electrical stimulation, suggesting that electrical stimulation acts as an abiotic elicitor of plant defense response to fungal diseases. The gene expression of PR1 but not PDF1.2 was upregulated in Arabidopsis plants subjected to electrical stimulation. On the other hand, PR1 gene expression was not induced in salicylic acid (SA)-insensitive Arabidopsis mutant npr1-5 subjected to electrical stimulation. Taken together, electrical stimulation is responsible for plant defense response through the SA-dependent defense pathway. These findings would help us develop a novel and innovative practical technique that uses electrical stimulation in integrated pest management.

The non-sulfated ulvanobiuronic acid of ulvans is the smallest active unit able to induce an oxidative burst in dicot cells

Ulvans from green algae are promising compounds for plant protection because they are environmentally friendly and induce plant defense responses. We analyzed the structure-function relationship of ulvan polymers and oligomers for their elicitor activity in suspension-cultured cells of three dicot species. The polysaccharide from Ulva fasciata was characterized regarding its monosaccharide composition, degree of sulfation, and molecular mass. The polymer was partially depolymerized using acid hydrolysis, and the oligomers were separated using size exclusion chromatography. The oligomeric fractions were analyzed revealing mostly sulfated and de-sulfated ulvan dimers. Both the polymer and the oligomer fractions induced an NADPH oxidase-dependent oxidative burst in plant cells. The elicitor activity of the ulvan dimers did not require sulfation. By identifying the smallest elicitor-active unit, HexA-Rha, we took an important next step to understand how the structure influences ulvan elicitor responses. The desulfated ulvan dimer is discussed as a promising agro-biologic for sustainable agriculture.

How to Unravel the Key Functions of Cryptic Oomycete Elicitin Proteins and Their Role in Plant Disease.

Pathogens and plants are in a constant battle with one another, the result of which is either the restriction of pathogen growth via constitutive or induced plant defense responses or the pathogen colonization of plant cells and tissues that cause disease. Elicitins are a group of highly conserved proteins produced by certain oomycete species, and their sterol binding ability is recognized as an important feature in sterol–auxotrophic oomycetes. Elicitins also orchestrate other aspects of the interactions of oomycetes with their plant hosts. The function of elicitins as avirulence or virulence factors is controversial and is dependent on the host species, and despite several decades of research, the function of these proteins remains elusive. We summarize here our current understanding of elicitins as either defense-promoting or defense-suppressing agents and propose that more recent approaches such as the use of ‘omics’ and gene editing can be used to unravel the role of elicitins in host–pathogen interactions. A better understanding of the role of elicitins is required and deciphering their role in host–pathogen interactions will expand the strategies that can be adopted to improve disease resistance and reduce crop losses.

Temperature Differentially Influences the Capacity of Trichoderma Species to Induce Plant Defense Responses in Tomato Against Insect Pests

Temperature Differentially Influences the Capacity of Trichoderma Species to Induce Plant Defense Responses in Tomato Against Insect Pests

Temperature Differentially Influences the Capacity of Trichoderma Species to Induce Plant Defense Responses in Tomato Against Insect Pests.

Species of the ecological opportunistic, avirulent fungus, Trichoderma are widely used in agriculture for their ability to protect crops from the attack of pathogenic fungi and for plant growth promotion activity. Recently, it has been shown that they may also have complementary properties that enhance plant defense barriers against insects. However, the use of these fungi is somewhat undermined by their variable level of biocontrol activity, which is influenced by environmental conditions. Understanding the source of this variability is essential for its profitable and wide use in plant protection. Here, we focus on the impact of temperature on Trichoderma afroharzianum T22, Trichoderma atroviride P1, and the defense response induced in tomato by insects. The in vitro development of these two strains was differentially influenced by temperature, and the observed pattern was consistent with temperature-dependent levels of resistance induced by them in tomato plants against the aphid, Macrosiphum euphorbiae, and the noctuid moth, Spodoptera littoralis. Tomato plants treated with T. afroharzianum T22 exhibited enhanced resistance toward both insect pests at 25°C, while T. atroviride P1 proved to be more effective at 20°C. The comparison of plant transcriptomic profiles generated by the two Trichoderma species allowed the identification of specific defense genes involved in the observed response, and a selected group was used to assess, by real-time quantitative reverse transcription PCR (qRT-PCR), the differential gene expression in Trichoderma-treated tomato plants subjected to the two temperature regimens that significantly affected fungal biological performance. These results will help pave the way toward a rational selection of the most suitable Trichoderma isolates for field applications, in order to best face the challenges imposed by local environmental conditions and by extreme climatic shifts due to global warming.

Wide-Field, Real-Time Imaging of Local and Systemic Wound Signals in <em>Arabidopsis</em>

Extracellular glutamate-triggered systemic calcium signaling is critical for the induction of plant defense responses to mechanical wounding and herbivore attack in plants. This article describes a method to visualize the spatial and temporal dynamics of both these factors using Arabidopsis thaliana plants expressing calcium- and glutamate-sensitive fluorescent biosensors.

β-Aminobutyric acid treatment accelerates the deposition of suberin polyphenolic and lignin at wound sites of potato tubers during healing

β-Aminobutyric acid (BABA) is a nonprotein amino acid that induces plant defense responses to numerous biotic and abiotic stresses. However, whether BABA treatment affects the wound healing process of potato tubers has yet to be reported. In this study, we examined the effects of BABA treatment on the weight loss and disease index of Solanum tuberosum L. cv. Atlantic potato tubers inoculated with Fusarium sulphureum and assessed the deposition of suberin polyphenolic (SPP) and lignin at the wound sites of these tubers during healing. We also investigated the indexes involved in phenylpropane metabolism, H2O2, and peroxidase in the underlying effect mechanism. BABA treatment effectively reduced the weight loss of wounded tubers (by 41.0 %) and the disease index of inoculated tubers (by 43.2 %) during healing (at 21 d and relative to the control). BABA treatment also accelerated the deposition of SPP and lignin at wound sites. SPP and lignin cell layers in the treated tubers were 58.45 % and 54.72 % thicker, respectively, than the equivalent cell layers in the controls at 7 d of healing. Additionally, BABA treatment significantly enhanced the activities of phenylalanine ammonia-lyase (PAL), 4-coumaryl coenzyme A ligase (4CL), cinnamic acid-4-hydroxylase (C4H), and cinnamyl alcohol dehydrogenase (CAD) while also promoting the synthesis of cinnamic acid, p-coumaric acid, caffeic acid, ferulic acid, sinapic acid, cinnamyl alcohol, coniferyl alcohol, and sinapyl alcohol, as well as increasing total phenolic and lignin content, at wound sites during healing. Furthermore, BABA treatment increased H2O2 content and peroxidase activity at the wounds. These results suggest that BABA treatment activates phenylpropanoid metabolism, increases H2O2 content and peroxidase activity, and accelerates the deposition of SPP and lignin in potato tuber wounds, all of which lead to reductions in the weight loss and disease index of tubers during healing.

Evaluation of the symbiotic performance of tomato plants inoculated with Bacillus velezensis NKG-2 and challenged with Fusarium wilt pathogen

There has been an increased interest in investigating how plants interact with microbes by inoculation of bacteria that promote plant growth. In this study, the effect of co-inoculation of tomato seedlings with B. velezensis NKG-2 and induction of plant defense response against F. oxysporum f. sp. lycopersici was assessed in greenhouse assay. This antagonistic strain protected tomato plants from the detrimental effect of Fusarium oxysporum f. sp. lycopersici, reducing the Fusarium wilt incidence. The plant fitness parameters (total chlorophyll and shoot nitrogen contents) from the plants inoculated with NKG-2 and fungal-pathogen-challenged plants were significantly higher than those in un-inoculated challenged plants. NKG-2-inoculated plants improved its root surface colonisation by forming biofilm-like structures and protected the plants against infectious pathogens. The results showed in this work will help to expand our understanding of the mode of action of NKG-2 as a biological control agent and consequently, its application in agriculture.

The molecular mechanism of efficient transmission of plant viruses in variable virus–vector–plant interactions

Plant viruses are mainly transmitted by insect vectors in the non-persistent, semi-persistent, or persistent modes. In the non-persistent mode, plant viruses are retained in the stylets of their insect vectors. In the semi-persistent mode, plant viruses are carried to vector foreguts or salivary glands, but they cannot spread to salivary glands. In the persistent mode, plant viruses are retained in vector guts and can spread to salivary glands. In the non-persistent and semi-persistent modes, plant viruses are retained for a short time and cannot enter the hemolymph of insect vectors, whereas in the persistent mode, plant viruses are retained for a relatively long time and can be found in the hemolymph. Here, we reviewed recent studies that uncovered molecular mechanisms of how plant viruses manipulate host traits for efficient transmission by insect vectors. Normally, plants that are infected with viruses, regardless of the transmission mode, tend to release more attractive volatiles to vectors. However, plant defensive systems are regulated differently by viruses in these three modes. In the non-persistent mode, virus infections significantly induce plant defense responses, which probably trigger vectors (e.g., winged aphids) to disperse and transmit viruses in a short time. In the semi-persistent mode, virus infections frequently suppress plant defense responses, resulting in an increase of vector population and facilitating viral transmissions during vector outbreaks. In the persistent mode, virus infections reduce plant defense responses and manipulate plant traits to become suitable feeding sites in a relatively long period of time. Understanding the underlying mechanisms of virus–vector–plant interactions will lay a foundation for preventing virus transmission.

FoEG1, a secreted glycoside hydrolase family 12 protein from Fusarium oxysporum, triggers cell death and modulates plant immunity.

Fusarium oxysporum is an important soilborne fungal pathogen with many different formae speciales that can colonize the plant vascular system and cause serious crop wilt disease worldwide. We found a glycoside hydrolase family 12 protein FoEG1, secreted by F. oxysporum, that acted as a pathogen‐associated molecular pattern (PAMP) targeting the apoplast of plants to induce cell death. Purified FoEG1 protein triggered cell death in different plants and induced the plant defence response to enhance the disease resistance of plants. The ability of FoEG1 to induce cell death was mediated by leucine‐rich repeat (LRR) receptor‐like kinases BAK1 and SOBIR1, and this ability was independent of its hydrolase activity. The mutants of cysteine residues did not affect the ability of FoEG1 to induce cell death, and an 86 amino acid fragment from amino acid positions 144 to 229 of FoEG1 was sufficient to induce cell death in Nicotiana benthamiana. In addition, the expression of FoEG1 was strongly induced in the early stage of F. oxysporum infection of host plants, and FoEG1 deletion or loss of enzyme activity reduced the virulence of F. oxysporum. Therefore, our results suggest that FoEG1 can contribute to the virulence of F. oxysporum depending on its enzyme activity and can also act as a PAMP to induce plant defence responses.