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硅和苯并噻二唑诱导烟草抗青枯病的机理分析

  • 摘要: 为了揭示叶面喷施矿质元素硅(Silicon, Si)和植物诱抗剂苯并噻二唑(Benzothiadiazole, BTH)对烟草抗青枯病的影响机制,分析测定了Si和BTH处理后烟株根系青枯病菌及根茎叶的硅含量(质量分数)、叶片防御酶系活性、叶片抗性相关基因的表达量,以及室内、田间烟草青枯病发病情况。结果表明,Si和BTH处理后的烟草根系青枯病菌含量log(CFU)/g均显著降低,且Si处理能够显著增加烟草根系的硅含量;Si和BTH处理后烟株叶片中的防御酶系活性均增强,其中Si处理可显著提高过氧化物酶(POD)与β-1, 3-葡聚糖酶(GLU)的活性,BTH处理能显著增强β-1, 3-葡聚糖酶(GLU)、多酚氧化酶(PPO)、苯丙氨酸解氨酶(PAL)的活性;Si和BTH处理对烟草抗性基因的表达量也有显著影响,EFE26ACC OxidaseHIN1PR2的表达量均显著提高,其中BTH处理后PR1PR1a/cEFE26ACC OxidaseHIN1的表达量显著高于Si处理,而Si可显著提高PR2的表达量,且显著高于BTH处理。Si是通过烟草根系硅含量的积累来抵抗青枯病菌的侵染,BTH则是以抗性相关基因表达量的显著提高来诱导烟草对青枯病的抗性。由此可见,叶面施用Si和BTH是以不同的途径诱导烟草抵抗青枯病。

     

    Abstract: To evaluate the effects of foliar spraying of two inducers (mineral elemental silicon, Si; plant elicitor benzothiadiazole, BTH) on tobacco bacterial wilt, the content of tobacco bacteria wilt pathogen in tobacco roots, the Si contents in tobacco roots, stalks and leaves, the activity of defense enzymes and the expressions of resistance genes in tobacco leaves and the incidence of tobacco bacteria wilt in laboratory and fields were analyzed after Si and BTH treatments. The results showed that the content of tobacco bacteria wilt pathogen in roots was significantly reduced by Si and BTH, and the Si content in the roots was significantly increased by the Si treatment. The activities of defense enzymes in leaves were also enhanced by the Si and BTH treatments, in which the activities of peroxidase (POD) and β-1, 3-glucanase (GLU) were significantly promoted by the Si treatment, as did those of GLU, polyphenol oxidase (PPO) and phenylalanine ammonialyase (PAL) by BTH. The expressions of resistance genes (EFE26, ACC Oxidase, HIN1 and PR2) in tobacco were significantly increased by both procedures, the expressions of PR1, PR1a/c, EFE26, ACC Oxidase and HIN1 were significantly higher in tobacco treated with BTH; while the expression of PR2 was significantly higher in tobacco treated with the Si treatment. Si induced the resistance to tobacco bacterial wilt through enhancing the Si accumulation in tobacco roots, as did BTH through promoting the expressions of resistance-related genes. In summary, this study demonstrated that foliar application of Si and BTH induced the resistance to tobacco bacterial wilt in tobacco in two different mechanisms.

     

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