Expression of the tobacco β-1,3-glucanase gene, PR-2d, following induction of SAR with Peronospora tabacina

Systemic acquired resistance (SAR) is induced following inoculation of Peronospora tabacina sporangia into the stems of Nicotiana tabacum plants highly susceptible to the pathogen. Previous results have shown that accumulation of acidic β-1,3-glucanases (PR-2's) following induction of SAR by P. tabacina may contribute to resistance to P. tabacina. We showed that up-regulation of the PR-2 gene, PR-2d, following stem inoculation with P. tabacina, is associated with SAR. Studies using plants transformed with GUS constructs containing the full length promoter from PR-2d or promoter deletions, provided evidence that a previously characterized regulatory element that is involved in response to salicylic acid (SA), may be involved in regulation of PR-2d following induction of SAR with P. tabacina. This work provides evidence that regulation of PR-2 genes during P. tabacina-induced SAR may be similar to regulation of these genes during infection of N-gene tobacco by TMV or following exogenous application of SA, and provides further support for the role of SA in regulation of genes during P. tabacina-induced SAR.     

The salicylic acid-dependent defence pathway is effective against different pathogens in tomato and tobacco

The role of salicylic acid (SA) was investigated in basal defence and induced resistance to powdery mildew ( Oidium neolycopersici ) and grey mould ( Botrytis cinerea ) in tomato ( Lycopersicon esculentum ) and tobacco ( Nicotiana tabacum ). A comparison of NahG transgenic tomato and tobacco (unable to accumulate SA) to their respective wild types revealed that in tomato, SA was not involved in basal defence against O. neolycopersici but NahG tobacco showed an enhanced susceptibility to O. neolycopersici infection, the effect becoming more obvious as the plants grew older. In contrast, SA played no role in the basal defence of tobacco against B. cinerea , but seemed to contribute to basal defence of tomato against B. cinerea. Activation of the SA-dependent defence pathway via benzothiadiazole (BTH) resulted in induced resistance against O. neolycopersici in tobacco but not in tomato. Microscopic analysis revealed that BTH treatment could prevent penetration of the Oidium germ tube through tobacco leaves, whereas penetration was successful on tomato leaves irrespective of BTH treatment. In contrast, soil or leaf treatment with BTH induced resistance against B. cinerea in tomato but not in tobacco. It is concluded that the SA-dependent defence pathway is effective against different pathogens in tomato and tobacco.     

大豆凝集素基因lec-s转化烟草>增强对烟草花叶病毒的抗性

 将编码大豆凝集素的lec-s基因插入植物表达载体pBI121中,构建植物重组表达质粒pBI121:: lec-s。由根癌土壤杆菌EHA105介导的叶盘法转化烟草,获得了转基因烟草株系。PCR和RT-PCR检测证明lec-s基因已转入烟草植株中。接种烟草花叶病毒（Tobacco mosaic virus,TMV）进行抗病性试验结果表明,转基因烟草叶片上的病斑数显著减少,说明转基因烟草表现出对TMV的抗性。定量RT-PCR检测发现,接种TMV后,抗病防卫基因（PR-1a、GST1、Pal和hsr515）在转基因烟草叶片中显著上调表达。这些结果表明,大豆凝集素基因lec-s转化烟草可对TMV产生抗性,其作用机制可能在于lec-s基因参与了植物的防卫信号通路,诱导了抗病防卫基因在转基因植株体内的表达,增强了植株对TMV的系统抗性。     

Induction of antiviral resistance and stimulary effect by oligochitosan in tobacco

Oligochitosan was applied by spraying it on tobacco leaves for inhibition of tobacco mosaic virus (TMV). The maximum inhibition of TMV by oligochitosan was observed when inoculation occurred at 24 h after spraying 50 μg ml⁻¹ oligochitosan. The production of H₂O₂ and NO in epidermal tobacco cells induced by oligochitosan was investigated by epidermal strip bioassay and LSCM, using cell permeable fluorophore diaminofluorescein diacetate (DAF-2D) and 2′,7′-dichlorofluorescin diacetate (H₂DCF-DA), respectively. Epidermal tobacco cells treated with oligochitosan resulted in a strong increase of intracellular NO and H₂O₂. Oligochitosan and NO donor sodium nitroprusside (SNP) induced the defense reaction against tobacco mosaic virus (TMV), and increased phenylalanine ammonia-lyase (PAL) activity. Co-treatment of the tobacco cells with oligochitosan and NO scavenger CPTIO blocked the inducing resistance. The results indicated that the defense response induced by oligochitosan was connected with NO pathway.     

Control of Tobacco mosaic virus by PopW as a result of induced resistance in tobacco under greenhouse and field conditions

In a previous study, we isolated a new harpin protein, PopW, from the bacterium Ralstonia solanacearum ZJ3721 that can induce a hypersensitive response in tobacco, Nicotiana tabacum, leaves. In the current study, we demonstrate that, in a greenhouse experiment, PopW induced tobacco-acquired resistance against the Tobacco mosaic virus (TMV) with a biocontrol efficacy of 80.9 to 97.4% at a concentration as low as 25 μg/ml in both PopW-treated and neighboring leaves. The resistance induced by PopW is systemic acquired resistance mediated by salicylic acid, which was certified by the development of resistance being accompanied by the expression of the pathogenesis-related-1 gene (PR1) 8 h after PopW was sprayed onto the tobacco leaves. In addition, hydrogen peroxide began to accumulate 10 h after PopW spraying, peaking at 24 h with a maximum concentration of 1.97 μM/g fresh weight. The activities of phenylalanine ammonia lyase (EC4.3.1.5), polyphenoloxidase (EC1.14.18.1), and peroxidase (EC1.11.1.7) also increased, peaking at different times in the PopW-treated tobacco leaves. PopW also reduced the level of TMV disease in field trials with a biocontrol efficacy of 45.2%. Furthermore, PopW both increased tobacco yield (by 30.4 more than in control plants) and improved tobacco foliar quality, with an increase of 50.2% in the number of first-class tobacco leaves from treated compared with untreated plants. All of these results indicate that the new harpin protein PopW has the potential to be an effective biocontrol agent against TMV in tobacco.     

Virus-specific expression of systemic acquired resistance in tobacco mosaic virus- and tobacco necrosis virus-infected ‘Samsun NN’ and ‘Samsun’ tobacco

Systemic acquired resistance induced in intact ‘Samsun NN’ tobacco plants by either tobacco mosaic virus (TMV) or tobacco necrosis virus (TNV) was more effective against challenge inoculation with the same than with the other of the two viruses. However, in trimmed ‘Samsun NN’ plants resistance induced by either of these viruses was stronger against TMV than against TNV. In intact ‘Samsun’ tobacco plants TNV induced a systemic resistance against itself identical to the one expressed in ‘Samsun NN’. Moreover, it induced systemic resistance against TMV as based on a decrease in TMV content in challeng-inoculated leaves. These observations indicate that systemic acquired resistance is not limited to combinations in which both inducing and challenging virus give rise to a hypersensitive reaction, and further point to virus-specific factors regulating the extent of resistance expressed.     

Suppressive effect of abscisic acid on systemic acquired resistance in tobacco plants

Recent studies have indicated that the phytohormone abscisic acid (ABA), induced in response to a variety of environmental stresses, plays an important role in modulating diverse plant–pathogen interactions. In Arabidopsis thaliana, we previously clarified that ABA suppressed the induction of systemic acquired resistance (SAR), a plant defense system induced by pathogen infection through salicylic acid (SA) accumulation. We investigated the generality of this suppressive effect by ABA on SAR using tobacco plants. For SAR induction, we used 1,2-benzisothiazole-3(2H)-one 1,1-dioxide (BIT) and benzo(1,2,3)thiadiazole-7-carbothioic acid S-methyl ester (BTH) that activate upstream and downstream of SA in the SAR signaling pathway, respectively. Wild-type tobacco plants treated with BIT or BTH exhibited enhanced disease resistance against Tobacco mosaic virus (TMV) and tobacco wildfire bacterium, Pseudomonas syringae pv. tabaci (Pst), however, which was suppressed by pretreatment of plants with ABA. Pretreatment with ABA also suppressed the expression of SAR-marker genes by BIT and BTH, indicating that ABA suppressed the induction of SAR. ABA suppressed BTH-induced disease resistance and pathogenesis-related (PR) gene expression in NahG-transgenic plants that are unable to accumulate SA. The accumulation of SA in wild-type plants after BIT treatment was also suppressed by pretreatment with ABA. These data suggest that ABA suppresses both upstream and downstream of SA in the SAR signaling pathway in tobacco.     

沼泽红假单胞菌蛋白Rhp-PSP对烟草花叶病毒的系统抗性诱导及互作蛋白筛选

本文研究了蛋白Rhp-PSP诱导烟草抗TMV过程中相关防御酶的活性以及丙二醛（MDA）含量的变化，同时测定了抗病相关基因的表达情况。试验证明，蛋白Rhp-PSP处理烟草后，叶片中苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）和多酚氧化酶（PPO）的活性显著提高，但降低了MDA含量。同时基因PR-1、PR-3、PR-5、PDF1.2表达显著上调，证明了蛋白Rhp-PSP具有诱导烟草产生抗TMV的活性。为阐明诱导抗性机制，利用酵母双杂交系统从烟草cDNA文库进行互作蛋白的筛选并验证，结果表明GPI锚定蛋白、VAN3结合蛋白及叶绿素结合蛋白A与蛋白Rhp-PSP互作。     

海带多糖对烟草花叶病毒的抑制作用及其对烟草酶活性的影响

为明确海带多糖抗病毒剂对烟草抗烟草花叶病毒（Tobacco mosaic virus,TMV）病的诱导抗性及其对TMV感染后的保护作用,采用间接酶联免疫吸附法（ELISA）研究0.5 mg/mL海带多糖水剂、0.5 mg/mL香菇多糖水剂、6.25 mg/L氨基寡糖素水剂和0.1 mg/mL盐酸吗啉胍.铜可湿性粉剂对TMV侵染的预防保护作用和对TMV感染植株的治疗作用,并检测施用海带多糖后烟草体内过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）及超氧化物歧化酶（SOD）活性的变化和海带多糖对感染TMV后烟草叶绿素含量的影响。接种前喷施0.5 mg/mL海带多糖后,再接种TMV病毒,其抑制率可达42.42%,与喷施6.25 mg/L氨基寡糖素抑制率44.96%的效果相当,预防保护作用较好;但两种药剂处理感病植株的治疗效果较差,其抑制率仅分别为38.93%和40.13%。海带多糖能够系统地诱导烟草体内POD、PAL及SOD活性,从而控制了感染TMV后烟草叶绿素含量下降。说明海带多糖可诱导植物产生抗病性。     

激活蛋白PeaT1诱导烟草对TMV的系统抗性

枯斑三生烟草(Samsun-NN)经激活蛋白PeaT1诱导后接种烟草花叶病毒(Tobacco mosaic virus,TMV),对TMV产生了明显的系统获得抗性,枯斑抑制率达54.15%,枯斑大小也受到一定程度的限制。研究结果表明,PeaT1处理烟草植株下位三片叶不同时间后,其上部叶片中PPO、POD和PAL 3种抗病防御酶活性均比对照提高,第4 d酶活性达到最高值。实时荧光定量PCR检测结果显示,经PeaT1诱导4 d后烟草叶片中抗病相关基因PR1a、PR1b、NPR1在转录表达水平上较未诱导对照都有不同程度的上调。由以上结果我们推测PeaT1诱导烟草产生了系统获得抗性,本研究为进一步阐明PeaT1诱导植物抗病的信号传导途径奠定了基础。     

Salicylic Acid Suppresses Potato virus Y Isolate N:O-Induced Symptoms in Tobacco Plants

ABSTRACT The effects of salicylic acid (SA) and 1-aminocyclopropane-1-carboxylic acid (ACC) on the systemic development of symptoms induced by a severe isolate of Potato virus Y group N:O (PVY(N:O)) in tobacco were investigated. Upon inoculation, the systemic development of symptoms in tobacco plants could be divided into three stages: virus incubation stage, rapid symptom-progress stage, and partial recovery and symptom-shifting stage. Treatment of seedlings with SA delayed the virus-induced necrosis in stems by 1 to 2 days. SA, not ACC, also significantly suppressed the symptom severity in stems. However, neither SA nor ACC treatment affected the partial recovery phenotype exhibited in the latterly emerged upper parts of the plants. Further analysis indicated that the accumulation of PVY was retarded by SA at the early stage of infection, and the effects were more profound in stems than leaves. Peroxidase (POX) activity and pathogenesis-related (PR) genes PR-1a and PR-1b were enhanced by PVY infection. SA not only increased POX activity in stems and PR genes in stems and leaves of mock-inoculated plants, but also elevated the activity of POX in both leaves and stems and the expression of PR-1a in leaves of PVY-infected plants. Together, the results suggest that systemic acquired resistance plays a key role in suppressing PVY(N:O)-induced symptom development through SA-mediated and ethylene-independent pathways. The symptom suppression was correlated with reduced replication/ accumulation of virus at the early stage of infection. The results also suggest that neither SA nor ethylene plays a role in the recovery phenotype.     

Comparison of the effects of salicylic acid and ethephon with virus-induced hypersensitivity and acquired resistance in tobacco

The induction of a hypersensitive reaction in Samsun NN tobacco by tobacco mosaic virus (TMV) at 20°C leads to the development of both localized and systemic acquired resistance, and is associated with the appearance of pathogenesis-related proteins (PR's) and large increases in peroxidase activity and ethylene production. Salicylic acid (SA) induced a similar resistance in treated plant parts and occasionally also in untreated upper leaves of plants of which three lower leaves had been injected. SA also induced the same four PR's, but these were confined to the treated leaves. Thus, the connection between the presence of PR's and the reduction of TMV multiplication and spread may not be direct.In contrast to TMV, SA did not stimulate ethylene production and hardly increased peroxidase activity. Induction of acquired resistance and PR's by SA developed equally well at 20°C and at 32°C. However, pricking leaves with needles moistened with the ethylene-releasing compound ethephon mimicked TMV infection in inducing acquired resistance and PR's in both treated and untreated leaves at 20°C, but not at 32°C. Ethephon increased peroxidase activity at both temperatures, but only at 20°C dit it induce changes in both the anodic and the cathodic isoenzymes that were similar to those induced as a result of TMV infection. SA induced PR's and reduced TMV multiplication in Samsun tobacco, and inhibited virus spread in Samsun NN at 32°C.These observation indicate that neither the induction of PR's, nor the development of acquired resistance is temperature-sensitive. On the other hand, the effects of ethephon are temperature-sensitive in the same way as the hypersensitive response to TMV. It can thus be hypothesized that ethylene, produced naturally during the hypersensitive reaction of tobacco to TMV, leads to the temperature-sensitive synthesis or release of a presumably benzoic acid-type compound that functions as the natural inducer of PR's and acquired resistance. Although vanillic acid has been shown to accumulate in hypersensitively reacting tobacco leaves, it produced none of the effects of SA, and thus cannot be the natural inducer.Samenvatting Inductie van een overgevoeligheidsreactie in Samsun NN-tabak door tabaksmozaïekvirus (TMV) bij 20°C leidt tot de ontwikkeling van een verworven resistentie die zowel lokaal als systemisch werkzaam is, en gaat samen met het verschijnen van pathogenesis-related proteins (PR's) en sterke toename in de activitieit van peroxidase en de produktie van ethyleen. Salicylzuur (SA) induceerde een vergelijkbare resistentie in behandelde plantedelen en af en toe ook in niet behandelde bovenbladeren van planten waarvan drie onderbladeren waren ingespoten. SA induceerde ook dezelfde vier PR's, maar deze waren beperkt tot de behandelde bladeren. Er bestaat dus geen directe samenhang tussen de aanwezigheid van PR's en de remming van de vermeerdering en uitbreiding van TMV in de plant.In tegenstelling tot TMV stimuleerde SA de ethyleenproduktie niet en verhoogde het de peroxidaseactiviteit nauwelijks. Inductie van verworven resistentie en PR's door SA trad even goed op bij 32°C als bij 20°C. Net als infectie met TMV leidde aanprikken van bladeren met naalden die gedoopt waren in een oplossing van ethefon — waaruit in het blad ethyleen vrijkomt — echter tot inductie van verworven resistentie en PR's in zowel behandelde als onbehandelde bladeren bij 20°C, maar niet bij 32°C. Ethefon verhoogde de peroxidaseactiviteit bij beide temperaturen, maar alleen bij 20°C induceerde het veranderingen in zowel de anodische als de kathodische isoënzymen die vergelijkbaar waren met die welke geïnduceerd werden als gevolg van infectie met TMV. SA induceerde PR's en verminderde de vermenigvuldiging van TMV in Samsun tabak, en remde de uitbreiding van het virus in Samsun NN bij 32°C.Deze waarnemingen tonen dat noch de inductie van PR's, noch de ontwikkeling van verworven resistentie een temperatuurgevoelig proces is. Daarentegen zijn de effecten van ethefon op dezelfde wijze temperatuurgevoelig als de overgevoeligheidsreactie op TMV. Men kan daarom veronderstellen dat ethyleen, dat op natuurlijke wijze geproduceerd wordt tijdens de overgevoeligheidsreactie van tabak op TMV, aanleiding geeft tot een temperatuurgevoelig proces, namelijk de synthese of het vrijkomen van een verbinding, vermoedelijk een benzoëzuurderivaat, dat fungeert als de natuurlijke inductor van PR's en verworven resistentie. Hoewel is aangetoond dat vanillinezuur zich ophoopt in overgevoelig reagerende tabaksbladeren, veroorzaakte deze verbinding geen enkel van de effecten van SA. Vanillinezuur kan dus niet de natuurlijke inductor zijn.     

Systemic resistance induced in Arabidopsis thaliana by Trichoderma asperellum SKT-1, a microbial pesticide of seedborne diseases of rice

BACKGROUND: Trichoderma asperellum SKT-1 is a microbial pesticide of seedborne diseases of rice. To investigate the mechanisms of disease suppression in SKT-1, the ability to induce systemic resistance by SKT-1, or its cell-free culture filtrate (CF), was tested using Arabidopsis thaliana Col-0 plants. RESULTS: Both SKT-1 and its CF elicit an induced systemic resistance against the bacterial leaf speck pathogen Pseudomonas syringae pv. tomato DC3000 in Col-0 plants. Involvement of plant hormones in the induced resistance by SKT-1 and CF was assessed using Arabidopsis genotypes such as the jasmonic acid (JA)-resistant mutant jar1, the ethylene (ET)-resistant mutant etr1, the plant impaired in salicylic acid (SA) signalling transgenic NahG and the mutant npr1 impaired in NPR1 activity. In soil experiments using SKT-1, no significant disease suppression effect was observed in NahG transgenic plants or npr1 mutant plants. Expression levels of SA-inducible genes such as PR-1, PR-2 and PR-5 increased substantially in the leaves of Col-0 plants. Expression levels of JA/ET-induced genes such as PDF1.2a, PR-3, PR-4 and AtVsp1 were also induced, but the levels were not as high as for SA-inducible genes. In a hydroponic experiment using CF from SKT-1, all Arabidopsis genotypes showed an induced systemic resistance by CF and increased expression levels of JA/ET- and SA-inducible genes in leaves of CF-treated plants. CONCLUSION: The SA signalling pathway is important in inducing systemic resistance to colonisation by SKT-1, and both SA and JA/ET signalling pathways combine in the signalling of induced resistance by CF. These results indicate that the response of A. thaliana is different from that found in root treatments with barley grain inoculum and CF from SKT-1. Copyright © 2011 Society of Chemical Industry     

牛蒡低聚果糖诱导烟草对烟草花叶病毒的抗性

在室内条件下,研究了牛蒡低聚果糖对烟草花叶病毒抗性的影响及其影响机制。结果表明,在牛蒡低聚果糖处理叶（第三叶）中,接种烟草花叶病毒24h时对照处理叶片中该病毒含量大约是牛蒡低聚果糖处理叶片中的2.6倍,相对防效达61%;在未处理叶（第四叶）中,接种烟草花叶病毒24h时对照处理叶片可检测到TMV-CP的表达,而牛蒡低聚果糖处理叶则检测不到TMV-CP的表达。通过对抗病相关基因的检测发现,牛蒡低聚果糖处理和接种烟草花叶病毒都可诱导抗病相关基因（包括PR-1a、PR-2、PR-3、PI-1、PI-2和PAL）在烟草局部叶和系统叶中大量表达。这些结果表明,牛蒡低聚果糖可诱导烟草对烟草花叶病毒产生抗性,其作用机制可能在于诱导了抗病相关基因在植株体内的表达,增强了植株的系统抗性。     

Activation of Defense Pathways: Synergism between Reactive Oxygen Species and Salicylic Acid and Consideration of Field Applicability

Treatment of tobacco with a mixture containing reactive oxygen species (ROS) and salicylic acid (SA) provided greater protection of tobacco against infection by Pseudomonas syringae pv. tabaci than either treatment alone. Synergism in expression from the promoter of the defense gene PR-1a was also observed. Although the ROS hydrogen peroxide and peracetic acid were poor inducers alone, they enhanced the level of -glucuronidase (GUS) activity expressed from the PR-1a promoter when applied with SA to a transgenic plant bearing a PR-1a::GUS fusion. PR-1a expression was not correlated with increased cell death as determined by Evans blue staining. There was no effect on the timing at which expression was increased by the mixture compared with the separate treatments. The mixture of hydrogen peroxide and SA partially mimicked the effect of a commercial product Oxycom that has field efficacy in improving plant performance. Repetitive applications of Oxycom enhanced expression from the PR-1a promoter and the production of the PR-1 protein. Enhanced activity occurred systemically both from aerial applications to single leaves and from root drenches. Root application strongly promoted veinal expression for the PR-1a promoter compared with confluent production in leaves of sprayed seedlings. Application methods and timing may aid in the success of activators of systemic acquired resistance in field conditions.     

The enhanced disease susceptibility phenotype of ethylene-insensitive tobacco cannot be counteracted by inducing resistance or application of bacterial antagonists

In an attempt to overcome the enhanced disease susceptibility phenotype that is typical for transgenic ethylene-insensitive tobacco (Tetr), Tetr plants were treated with chemical agents that induce resistance or with antagonistic rhizobacteria. Treatments with β-aminobutyric acid (BABA), benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH), methyl jasmonate (MeJA), or salicylic acid (SA) induced PR-genes generally to a lesser extent than in non-transformed plants and did not reduce wilting symptoms upon infection with Pythium sp., except for a marginal effect of SA. In Tetr lines overexpressing PR-1g, PR-5c, or both, no significant reduction in disease development was apparent. Also treatment of Tetr plants with the antagonistic rhizobacteria Bacillus cereus UW85, Pseudomonas aeruginosa 7NSK2, Pseudomonas fluorescens WCS417r or Q8r-196, Pseudomonas putida WCS358r, or antibiotic-producing derivatives of WCS358r, did not reduce symptoms caused by Pythium.     

Induction of systemic resistance against Cucumber mosaic virus by Penicillium simplicissimum GP17‐2 in Arabidopsis and tobacco

The plant growth‐promoting fungus, Penicillium simplicissimum GP17‐2, was evaluated for its ability to induce resistance against Cucumber mosaic virus (CMV) in Arabidopsis thaliana and tobacco plants. Treatment with barley grain inoculum (BGI) of GP17‐2 significantly enhanced fresh weight, dry weight and leaf number of A. thaliana and tobacco plants 6 weeks after planting. Two weeks after CMV inoculation, all plants treated with BGI of GP17‐2 or its culture filtrate (CF) showed a significant reduction in disease severity compared with non‐treated control plants, which exhibited severe mosaic symptoms by the end of the experiment. The enzyme‐linked immunosorbent assay (ELISA) demonstrated that CMV accumulation was significantly reduced in plants treated with GP17‐2 or its CF relative to control plants. Based on RT‐PCR, plants treated with GP17‐2 (BGI or CF) also exhibited increased expression of regulatory and defence genes involved in the SA and JA/ET signalling pathways. These results suggested that multiple defence pathways in A. thaliana and tobacco were involved in GP17‐2‐mediated resistance to CMV, although neither the transgenic NahG line, nor the npr1, jar1 or ein3 mutants disrupted the response in A. thaliana. This is the first report to demonstrate the induction of systemic resistance against CMV by GP17‐2 or its CF.     

Differential necrotic lesion formation in soybean cultivars in response to soybean mosaic virus

In this study, we examined the necrosis phenotype on leaves of two cultivars of soybean (ZheA8901 and Nannong1138-2) that show varying level of resistance to soybean mosaic virus (SMV). The necrotic symptoms seen on inoculated and systemic leaves of soybean cultivar ZheA8901 were reminiscent of programmed cell death (PCD). The cell death phenotypes were evaluated using the TUNEL method, quantification of hydrogen peroxide (H₂O₂) and salicylic acid, callose production, as well as by monitoring expression of defence genes GmPR-1 and GmNPR1. Our results show that SMV inoculation induced PCD on ZheA8901 is associated with rapid increase in H₂O₂, increased SA and callose accumulation and higher defence gene expression.