Induction of defence-related enzymes and resistance by the plant activator acibenzolar-S-methyl in tomato seedlings against bacterial canker caused by Clavibacter michiganensis ssp. michiganensis

Using tomato seedlings, the plant defence activator acibenzolar-S-methyl (benzo-[1,2,3]-thiadiazole-7-carbothioic acid-S-methyl ester, ASM; Bion 50 WG) was assayed for its ability to induce resistance against Clavibacter michiganensis ssp. michiganensis , the causal agent of bacterial canker of tomato. In ASM-pretreated plants, reduction in disease severity (up to 76·3%) was correlated with lower bacterial growth (up to 68·2% lower) during the time course of infection. To understand the possible mechanism of action of ASM, alterations in the activities of peroxidase (POX) and chitinase were assessed as markers of resistance. The enhanced resistance of ASM-treated plants was associated with significant increases in the activities of POX and chitinase     

氟唑活化酯对黄瓜抗枯萎病的诱导作用

【目的】诱导抗病剂可以诱导寄主植物的系统抗病性作用,具有持效性和广谱性的特点,研究旨在明确新型诱导抗病剂氟唑活化酯（fluoro-substituted benzothiadiazole derivatives,FBT）对黄瓜抗枯萎病的诱导作用,为该化合物的诱导抗病性机理的深入研究提供参考。【方法】利用50 mg·L^-1 FBT在黄瓜苗期移栽前3-4片真叶时喷雾诱导1次,3 d后移栽定植于含有黄瓜枯萎病菌（Fusarium oxysporum f. sp. cucumerinum Owen）的土壤中,缓苗后以叶面喷雾的方式进行第2次诱导,之后每隔7 d喷雾诱导1次,共诱导3次,对照诱导抗病剂苯并噻二唑（BTH）也采用同样的诱导方法,对照杀菌剂70%甲基硫菌灵可湿性粉剂1 500倍液则采用灌根施药,通过调查病情指数以评价其对枯萎病的抗病作用;研究FBT对枯萎病菌侵染黄瓜的影响,将供试黄瓜催芽至0.5 cm胚根后,浸泡于50 mg·L^-1 FBT中胚根诱导1次,待播种后黄瓜生长至2片子叶期开始第2次诱导,以后每隔7 d诱导1次,共诱导3次,第3次诱导后24 h灌根接种黄瓜枯萎病菌,并于接种后1、3、5、7、9、11、14、16、20、24、29 d分别取黄瓜根组织,于冰水中清洗,利用酸性品红染色技术评价FBT诱导黄瓜后对枯萎病菌侵染的影响,利用Maule反应和甲苯胺蓝染色技术评价FBT对黄瓜根组织中木质素和酚类物质的沉积情况的影响,利用分光光度-比色法测定FBT诱导黄瓜后根组织中富含羟脯氨酸糖蛋白（HRGP）及β-1,3-葡聚糖酶活性,以分析FBT诱导黄瓜后根组织抗病性变化情况。【结果】诱导抗病性表达发现,50 mg·L^-1的FBT对黄瓜抗枯萎病的诱导效果可达62.01%,高于对照诱导抗病剂BTH和杀菌剂70%甲基硫菌灵可湿性粉剂的防治效果。FBT诱导后的黄瓜在接种后7 d开始有枯萎病菌的侵染,此时未诱导只接种的黄瓜根组织因受枯萎病菌侵染,已经出现大量菌丝及孢子,FBT的诱导增强了寄主的抗病性反应,从而抑制了病原菌的侵染。同时经FBT诱导后4 d未接种及诱导后接种两个处理的根组织中具有大量褐色木质素沉积,尤其是根表皮细胞壁及韧皮部木质素沉降量明显,表现深褐色。对酚类物质的观察发现,在FBT诱导后2 d开始出现酚类物质沉积,诱导后4和6 d时,根组织中荧光信号较强,酚类物质沉积量较大,诱导后8 d时,根组织中荧光信号消失,酚类无明显沉积,木质素和酚类物质积累量的增加,以达到增强细胞壁的抗性,抵御病原菌的侵染的作用。在FBT诱导后1 d抗病相关蛋白HRGP和β-1,3-葡聚糖酶活性也明显增强,并一直保持在较高水平,为抵御病原菌侵染做准备。【结论】FBT诱导黄瓜产生了对枯萎病的抗病作用,同时黄瓜根组织通过次生代谢物质沉积量的增加及抗病相关蛋白活性增强,达到增强寄主根组织细胞壁的抗性,从而抵御病原菌的侵染,是具有发展前途的新型诱导抗病剂。     

苯并噻二唑诱发水稻对稻瘟病抗性中防卫相关酶活性的变化

分析了苯并噻二唑（BTH）诱导水稻对稻瘟病抗性中苯丙氨酸解氨酶（PAL）、肉桂醇脱氢酶（CAD）、过氧化物酶（POD）、脂氧合酶（LOX）、β-1,3-葡聚糖酶和几丁酶等活性的变化。结果表明BTH诱导处理亲和性水稻品种第3叶后提高了处理叶及其上位第4叶中CAD、LOX和β-1,3-葡聚糖酶等的活性;经BTH处理的幼苗接种稻瘟菌后,处理叶和其上位叶中CAD、POD、LOX和β-1,3-葡聚糖酶等活性快速增加,且增长幅度均显著大于对照。几丁酶活性在受稻瘟菌侵染后升高,但BTH诱导处理并不能促进其增加;PAL活性在BTH处理及稻瘟菌接种后均无明显变化。这些结果说明,BTH处理能诱导CAD、POD、LOX和β-1,3-葡聚糖酶等活性的增加,而且这些酶活性的升高可能与BTH诱发系统获得抗性的表现有关。     

苯并噻二唑对漂浮育苗烟草白粉病的诱导抗性及其对烟苗安全性研究

测定了苯并噻二唑对烟草白粉病菌的毒力、防治烟草白粉病的持效期以及对烟苗的安全性。结果表明,苯并噻二唑对烟草白粉病具有很高的诱导活性,随着药剂浓度的增加,烟草白粉病的发病率和病情指数均显著降低,它对烟草白粉病菌的EC50和EC90分别为3.30μg/mL和10.49μg/mL;苯并噻二唑对烟草白粉病具有较长的持效期,50%苯并噻二唑水分散粒剂23g/hm2 2次喷雾处理4叶期烟苗,30d后的防效仍然达到100%,它对烟草新生烟叶具有良好的保护作用;此外,50%苯并噻二唑水分散粒剂>95g/hm2喷雾烟苗会给烟苗造成严重药害,主要表现为烟苗生长滞缓,叶片坏死和黄化。     

氟唑活化酯诱导大白菜抗根肿病效果与机理初步研究

为明确新型植物诱导抗病剂氟唑活化酯对大白菜根肿病的诱导抗病效果及抗病机理,研究了氟唑活化酯的诱导浓度、在白菜根部的运输过程以及氟唑活化酯诱导白菜后相关防御基因的表达情况。结果显示以氟唑活化酯25 mg ? L-1对大白菜进行叶面喷雾诱导时根肿病的病情指数最低。通过台盼蓝（Trypan blue）染色观察到氟唑活化酯诱导大白菜叶片后,根部对根肿菌也产生了一定的抗性。利用Real-time PCR技术检测大白菜防御相关基因的表达,发现氟唑活化酯诱导大白菜2 h后JA途径中的COI1和LOX2基因以及SA途径中的PR-1基因都有显著的过量表达,其中JA信号途径相关基因表达变化更明显。结果说明氟唑活化酯可以诱导大白菜产生系统获得抗性,两种信号传导途径都参与了抗病过程,但以JA途径为主,SA途径为辅。     

植物激活剂苯并噻二唑（BTH）的研究进展

苯并噻二唑（BTH）是第一个成功商品化的植物激活剂Bion的有效成分。BTH是一种典型的植物抗病诱导剂,离体条件下无杀菌活性,但能够诱导植物的免疫活性,起到抗病、防病的作用。现对苯并噻二唑的特点、诱导植物的种类、抗病机制等进行了归纳总结,分析了目前苯并噻二唑应用中存在的问题,探讨了其进一步的发展前景。     

苯并噻二唑诱发水稻对白叶枯病的系统获得抗性

用苯并噻二唑（benzothiadiazole, BTH)(0.5 mmol/L）、水杨酸（1 mmol/L）、硝酸镍(0.5 mmol/L)、多效唑（300 mg/L）和烯效唑（40 mg/L）处理4叶1心期稻苗后接种白叶枯病菌,病斑长度明显降低。BTH对白叶枯病病菌生长无明显抑制作用。BTH诱发稻苗对白叶枯病抗性的最佳浓度为0.5~1 mmol/L;在诱发处理和接种之间至少需要2 d才能诱导抗性,间隔7 d的诱导抗性效果最好,诱导抗性的持久期至少15 d。BTH处理稻苗第2叶,可使未处理的第3和第4叶上也表现出诱导抗性,但处理后至少需要24~36 h上部叶片才表现出诱导抗性。结果表明,BTH诱导对白叶枯病的抗性是一种系统获得抗性反应。     

Protection of Brassica seedlings against downy mildew and damping-off by seed treatment with CGA 245704, an activator of systemic acquired resistance

Control of seedling diseases is a major priority in many crop systems. Seed treatments that induce systemic resistance after seedling emergence may be an ideal way to provide protection against disease during the establishment of the crop. CGA 245704, a chemical activator of systemic acquired resistance, was tested as a seed treatment against two Brassica diseases with contrasting infection biologies, the airborne downy mildew pathogen, Peronospora parasitica, and the soilborne fungus, Rhizoctonia solani. Seeds of two Brassica spp. were either imbibed with various concentrations of the compound or imbibed and then dried. Both the imbibition treatment alone and the imbibition treatment followed by seed drying had a significant effect on the sporulation intensity of P. parasitica for all concentrations of the compound used, whereas the imbibition treatment provided some control of damping-off caused by R. solani, with the degree of control being highly dependent on the concentration applied to the seed. Seed treatment with the plant activator CGA 245704 might therefore simultaneously control several seedling diseases, thereby providing a novel option for management of these diseases. © 1998 SCI.