油菜素内酯与美极梅奇酵母复配对葡萄灰霉病的抑制作用

Combined application of brassinosteroid and Metschnikowia pulcherrima against controls Botrytis cinerea on grape berries

摘要:

【背景】生防酵母具有繁殖速度快、抗逆性强和不产生抗生素等特点，但其对病害的防控效果易受环境影响，油菜素内酯(brassinosteroid，BR)能调控植物生长发育与逆境响应平衡，可有效抑制葡萄果实灰霉病的发生。【目的】本研究旨在明确BR与生防酵母复配对葡萄果实灰霉病的抑制效果及作用机制，为新型生防制剂的研制和应用提供理论依据。【方法】采用美极梅奇酵母P01C004 (Y)、酵母和BR (YBR)、酵母和BR抑制剂(YBZ)处理“红地球”葡萄果实，处理6 h后人工接种灰霉菌孢子悬液。灰霉菌接种7 d后评价BR与生防酵母复配对灰霉菌的防治效果，并检测其抗氧化酶活性和13种酚类物质含量，利用qRT-PCR检测不同处理对葡萄BR、白藜芦醇和抗病相关基因表达水平的影响。【结果】7 d时，与Y处理相比，YBR对葡萄果实灰霉病防治效率提高了23.64%，显著提高了“红地球”葡萄果实中PPO酶活。YBR显著提高了2 d时果实中绿原酸、原儿茶酸、咖啡酸、表儿茶素和芹菜素等酚类物质含量，激活了果实内多种酚类物质的快速合成。YBR在48 h时激活了果实BR信号转导途径，显著上调VvBZR1和VvPR1基因的表达水平，更好地维持植物免疫反应，提高果实对病原菌的防御力。【结论】BR与美极梅奇酵母复配能触发果实多种抗病防御机制，提高葡萄果实灰霉病的防治效率，在采后病害防控方面表现出良好的应用前景。

Abstract:

[Background] The yeast for biocontrol is characterized by rapid growth, strong stress resistance, and absence of antibiotic production. However, their biocontrol effects are easily influenced by environmental conditions. Brassinosteroid (BR) regulates the balance between plant growth and stress response and efficiently controls the occurrence of gray mold (Botrytis cinerea) on grape berries. [Objective] To investigate the effect and mechanism of Metschnikowia pulcherrima combined with BR in controlling B. cinerea on grape berries, and to provide a theoretical basis for the development and application of new biocontrol agents. [Methods] The berries of ‘Red Globe’ grape were treated with M. pulcherrima P01C004 (Y), P01C004+BR (YBR), and P01C004+brassinazole (YBZ), respectively. The spore suspension of B. cinerea was inoculated on the grape berries 6 h after the Y, YBR, and YBZ treatments. The efficiency of disease control, the activities of antioxidant enzymes, and the content of 13 phenolic compounds were evaluated 7 days after the inoculation of B. cinerea. qRT-PCR was performed to quantify the expression of the genes related to BR signaling pathway and pathogenesis under different treatments. [Results] Compared with Y treatment, YBR increased the control efficiency against B. cinerea by 23.64% and significantly improved the activities of polyphenol oxidase in grape berries. YBR significantly increased the content of chlorogenic acid, protocatechin, caffeic acid, epicatechin, and apigenin, and activated the rapid synthesis of phenols 2 days after inoculation. YBR activated the BR signaling pathway and up-regulated the expression levels of genes VvBZR1 and VvPR1 at the time point of 48 h, which sustained the plant immunity and induced strong defense responses of grape berries to the pathogen. [Conclusion] The combined application of M. pulcherrima and BR triggered multiple defense mechanisms of grape and improved the control efficiency against B. cinerea on grape berries, demonstrating a promising prospect in the postharvest disease control.