Sr18生物杀线制剂对植物根结线虫病害作用机理的研究

Root-knot nematodes (Meloidogyne spp.) are phytonematodes, which are destructive pests to many crops and cause significant crop yield losses annually in the world. Now they are the major soil-borne disease in facility agriculture and become the bottleneck of sustainable protected vegetable product. Due to the lack of thorough and systematical research on mechanism of action of biological nematicides, it impedes the development of high-efficiency commercialization of nematicides. Biocontrol agent-Sr18, developed by us group, characterized by heat-resisting, water soluble, wide range of nematicidal activity and also characterized by high-efficiency to root knot nematodes of Cucumis sativus L. and Lycopersicum esculentum and increasing crop production obviously. Basing on the demand of production practice and problem of biocontrol of root-knot nematodes in and outside China, combining traditional techniques of physiology, biochemistry and ultramicrostructure of high resolution with new technique of systems biology-metabonomics, the scientific research item goes in for illustrating the mechanism of action of Sr18 from the aspects of physiology and biochemistry, ultra-structures and metabolome changes of root-knot nematode and metabolome change of cucumber in vivo and in vitro. It will lay theoretical and practical foundations in developing Sr18 into commercial high-efficiency nematicide with independent intellectual property right and building the metabonomics study platform of phytonematodes as well as developing new high-efficiency biocontrol agents in future.

植物寄生线虫南方根结线虫为多种农作物的寄生虫害，每年在全球范围内对农作物造成严重损失，是设施农业中土传病害引起连作障碍的主要因素，已成为设施蔬菜可持续生产的瓶颈。由于对生物源杀线剂作用机理缺乏深入系统的研究，限制了高效生物杀线商品化制剂的研制。本课题组制备的Sr18生防制剂具有耐热、水溶性、杀线虫谱广及对黄瓜等根结线虫病害防效高、增产作用明显等特点。本项目针对目前国内外根结线虫病害生防存在的问题及生产实践的需要，充分利用学科交叉的优势，将传统研究手段与系统生物学中新兴技术-代谢组学相结合，以南方根结线虫和黄瓜为供试线虫和寄主植物，以Sr18 生防制剂为处理药剂，系统深入地研究Sr18生防制剂防治该病害的作用机理，为今后建立植物寄生线虫代谢组学研究平台及开发新型生物杀线剂做有益的探索。对于生物源物质防治植物根结线虫病害作用机理的研究对于今后开发新型高效生物杀线剂具有十分重要的理论与实践意义。

根结线虫病害在蔬菜保护地中造成的损失十分严重，甚至绝产，其防治已成为设施蔬菜可持续生产的瓶颈。生物防治是突破这一瓶颈的有效途径之一。由于对生物源杀线剂作用机理缺乏深入系统的研究，限制了生物杀线制剂的商品化进程。Sr18生防制剂是本课题组自主研发并经田间试验证实对黄瓜等根结线虫病害防效高、具有增产作用和环境友好特点的生防制剂，极具开发前景。为揭示其杀线机理，探明其与植物及线虫三者之间的关系，本项目将传统研究手段与新兴的代谢组学相结合，以南方根结线虫和黄瓜为对象，系统地研究了供试线虫和寄主植物在Sr18生防制剂作用下的超微结构、酶学以及代谢物组学变化等内容，并针对其作用机理进行了分析。代谢物组学分析显示，Sr18 生防制剂可明显改变根结线虫体内代谢物的含量，处理与对照组间差异显著的达54种，涉及三大代谢途径及膜结构组分，可导致细胞的损伤和细胞膜构建受阻。Sr18 生防制剂引发的糖代谢通路受阻、糖异生、能量断供，以及氧化应激关键物下调应是线虫致死的因素。抗氧化保护酶系（CAT、SOD、POD）、应激反应和解毒酶（TChE，GST），以及ATP酶的测定结果也提供了相应的酶学依据。超微结构的观察结果显示，Sr18 生防制剂可造成线虫体内的组织细胞消解，并经体表局部穿孔外溢而导致虫体皱缩干瘪而非体表崩解，表明其致死的机理是组织细胞的毒性所致，而非触杀性的腐蚀消解。对寄主植物黄瓜的研究结果显示，Sr18 生防制剂对正常栽培的黄瓜植株有促进生长的作用；对线虫侵染的黄瓜植株则具有明显的保护及提高抗性的作用。代谢物组学分析显示，该制剂可通过上调/下调相关代谢物来拮抗因线虫侵染导致的代谢物的上调/下调造成的伤害；酶学分析和超微结构观察的结果也显示出同样的趋势。研究结果不仅丰富了真菌杀线剂作用机理的研究成果，还为今后建立植物寄生线虫代谢组学研究平台及开发新型生物杀线剂提供了有益的借鉴。