烟草青枯病复配诱抗剂筛选及增效作用机制

Screening of compound plant elicitors and the synergistic mechanism for controlling tobacco bacterial wilt

    摘要
  • 摘要: 【目的】筛选最佳类黄酮复配诱抗剂,明确类黄酮复配诱抗剂在防治烟草青枯病中的增效作用机制,为提高烟草青枯病的防控水平及开发新型复配诱抗剂提供科学依据。【方法】以类黄酮(黄酮和橙皮素)为研究对象,将浓度为200 mg/L的8种助剂分别与1 mmol/L黄酮和1 mmol/L橙皮素进行复配,筛选可以与黄酮和橙皮素进行复配的助剂;通过室内盆栽试验测定复配诱抗剂在防控烟草青枯病中的作用,筛选获得最佳复配诱抗剂。进一步评价最佳复配诱抗剂对烟草青枯病的防治作用,并测定烟株过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性,采用实时荧光定量PCR技术测定烟株抗病相关基因NtPR1a、NtPAL、NtNPR1、NtHIN1和NtEFE26的表达水平,明确复配诱抗剂在防控烟草青枯病中的作用机制。【结果】8种助剂中,二氧化硅和卵磷脂可提升黄酮及橙皮素对烟草抗青枯病的防效,适宜浓度分别为50和100 mg/L。与类黄酮单剂相比,复配诱抗剂(1 mmol/L黄酮+50 mg/L二氧化硅、1 mmol/L黄酮+100 mg/L卵磷脂、1 mmol/L橙皮素+50 mg/L二氧化硅和1 mmol/L橙皮素+100 mg/L卵磷脂)对烟草青枯病的防效提升36.88%~67.21%。复配诱抗剂可明显提高烟草叶片中POD、PPO和PAL等防御酶活性,与黄酮单剂相比,施用黄酮+卵磷脂后烟草叶片中POD、PPO、PAL活性分别提高19.47%~37.95%、25.89%~66.91%和22.98%~254.83%;与橙皮素单剂相比,施用橙皮素+卵磷脂后烟草叶片中POD、PPO、PAL活性分别提高3.69%~114.37%、12.27%~58.04%和28.12%~104.39%。复配诱抗剂处理后烟草抗病相关基因NtNPR1、NtPR1a和NtHIN1的相对表达量均显著高于单施黄酮、橙皮素及清水对照处理(P<0.05)。【结论】50 mg/L二氧化硅和100 mg/L卵磷脂可提升1 mmol/L黄酮及1 mmol/L橙皮素对烟草青枯病的防控效果,提高烟株防御酶活性以及抗病相关基因的表达,可用于新型复配诱抗剂的开发。

     

    Abstract: 【Objective】The objective of this study was to screen out the best flavonoid compound elicitors, clarify the synergistic mechanism of them on controlling tobacco bacterial wilt, and provide scientific basis for improving the controlling effect against tobacco bacterial wilt and developing new plant compound elicitors.【Method】Flavonoids(flavonoid and hesperidin) were studied. Eight additives(concentrations of 200 mg/L) and 1 mmol/L flavonoid, 1 mmol/L hesperidin were mixed together, to screen the additives that could compound with flavonoid and hesperidin. The effects of them on controlling tobacco bacterial wilt were determined, and the best compound elicitors were screened out by indoor pot experiment. To further evaluate the controlling effect of the best compound elicitors against tobacco bacterial wilt, the mechanism of compound elicitors on controlling tobacco bacterial wilt was clarified by measuring the activities of enzymes such as oxidase(POD), polyphenol oxidase(PPO) and phenylalanine ammonolyase(PAL) in tobacco and the expression levels of some resistance-related genes(NtPR1a, NtPAL, NtNPR1, NtHIN1 and NtEFE26) in tobacco using fluorescence quantitative real-time PCR.【Result】Among 8 additives, silica and lecithin could enhance the effects of flavonoids and hesperidin on controlling tobacco bacterial wilt, and the suitable concentrations were 50 and 100 mg/L respectively. Compared with the single agent of flavonoids, the effect of flavonoid compound elicitors(1 mmol/L flavonoid+50 mg/L silica, 1 mmol/L flavonoid+100 mg/L lecithin, 1 mmol/L hesperidin+50 mg/L silica, 1 mmol/L hesperidin+100 mg/L lecithin) on controlling tobacco bacterial wilt increased by 36.88% to 67.21%. The treatment of flavonoid compound elicitors significantly improved the activities of POD, PPO and PAL in tobacco leaves. Compared with a single agent of flavonoid, the activities of POD, PPO and PAL in tobacco leaves increased by 19.47%-37.95%, 25.89%-66.91%, 22.98%-254.83% in flavonoid+lecithin treatment respectively;compared with a single agent of hesperidin, the activities of POD, PPO and PAL in tobacco leave sincreased by 3.69%-114.37%, 12.27%-58.04%, 28.12%-104.39% in hesperidin+lecithin treatment respectively. Compared with a single agent of flavonoid or hesperidin or the water control group, the application of flavonoid compound elicitors also significantly increased the relative expression levels of resistance-related genes NtNPR1, NtPR1a and NtHIN1(P<0.05).【Conclusion】50 mg/L silica and 100 mg/L lecithin can promote the effects of 1 mmol/L flavonoids and 1 mmol/L hesperidin on controlling tobacco bacterial wilt, and strengthen the activities of defense enzymes and the expression levels of resistance-related genes. This study lays the foundation for the development of new plant elicitors.

     

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