天然环五肽malformin A1抑制TMV增殖作用机理

Plant viruses, which cause dramatic losses in agriculture and horticulture all over the word, are hard to control and there are no ideal agents available at present for field application. Malformin A1, a natural cyclic penta-petide produced by fungus metabolism, is a reported plant growth regulator. Metabolites of more than 200 endophytic fungi were screened for their antiviral activities in our previous study. From the metabolites of one Aspergillus tubingensis strain of them, malformin A1 was obtained through bioassay-guided isolation and has been firstly proved to be a highly effective inhibitor on Tobacco mosaic virus (TMV) proliferation. Malformin A1, which could be industrially produced by application of fermentation engineering, is of great value as a leading compound with prospect of development and application as antiviral agent. However, not any related information concerning the antiviral properties of malformins is now available. TMV is the type member of the genus Tobamovirus and serves as a most commonly used target for discovery of bioactive antiviral natural products. In this project, detailed schemes and technological routes are designed to reveal the effect of malformin A1 on TMV protein (CP and MP) expression, RNA replication, and virus movement and spread, as well as to identify whether or not plant defense response could be induced. The research is of great importance to provide evidences to clarify the underlying inhibitory mechanism of malformin A1 on plant virus proliferation, and furnish scientific basis for its reasonable exploitation and application as an antiviral agent.

植物病毒病危害重、防治难，缺乏理想的田间防治药剂。天然环五肽malformin A1是真菌代谢产生的一种植物生长调节物质。基于200多株植物内生真菌代谢物质的抗病毒活性筛选，我们从一株塔宾曲霉发酵液中通过活性跟踪分离得到malformin A1，并率先证实了其对植物病毒增殖具有很强的抑制作用。malformin A1抑制烟草花叶病毒（TMV）增殖效果好且可通过发酵工程大量制备，是一种具备开发成为植物病毒抑制剂应用前景的天然先导化合物。本项目拟以正单链RNA模式病毒—TMV为靶标，综合应用Western blot、Northern blot、实时荧光定量PCR、绿色荧光蛋白标记等方法，通过研究malformin A1对TMV蛋白表达、核酸复制、病毒在寄主植物体内移动和扩散的影响以及是否能够诱导植物抗性等，全面揭示畸形素A1抑制TMV增殖的作用机理，为新型高效植物病毒抑制剂的开发奠定基础。

malformin A1是曲霉属真菌代谢产生、具有调节植物生长作用的一种天然环五肽。基于前期的研究基础，在国家自然科学基金的资助下，我们对malformin A1抑制烟草花叶病毒（Tobacco mosaic virus, TMV）增殖的作用机理进行研究。综合运用荧光光谱法、高效液相色谱法、Western-blot、实时荧光定量PCR和绿色荧光蛋白标记的方法，我们证实malformin A1可以显著抑制TMV病毒外壳蛋白的表达，影响病毒在寄主植物体内的增殖和扩散。更为重要的是，malformin A1可以诱导寄主植物合成和积累植保素–东莨菪苷，刺激植物产生病程相关蛋白及调控抗病反应相关基因的表达，激活寄主植物的防卫反应，从而提高植物的整体抗病性。