入侵生物学的核心科学问题就是入侵种的入侵性，而入侵成功的物种普遍具有繁殖力强的特性来克服入侵初期物种小种群瓶颈效应。松材线虫作为世界性重大外来入侵种在入侵过程中也发生繁殖能力增强现象，但其繁殖表型变化的环境驱动及其内在分子和遗传机制尚不清楚。双丙酮醇是我们在前一基金项目工作基础上发现的一种接种松材线虫伴生真菌Sporothrix sp.1后诱导寄主松树产生的特异化合物，该物质对中美松材线虫繁殖具有促进作用，而该菌又是一在中国发现的新伴生菌。这为我们从繁殖力表型可塑性研究入侵机制提供了一独特的模式。本项目通过化学生态和分子生物学手段研究这一化合物对松材线虫繁殖的促进和中美松材线虫化感和繁殖相关基因的遗传变异和表达调控，阐明其对中美松材线虫的繁殖促进机制。进而从本地蓝变菌协同互作促进繁殖力这一角度揭示松材线虫的入侵机制。不同于现有的"新武器假说"，本项目涉及蓝变菌、寄主松树和松材线虫三级互作。

The invasiveness of an invasive species is the key scientific question in invasion biology while most invasive species posses propagation plasticity to overcome the bottle neck effect at initial invasion stage. Generally invasive species usually has higher fecundity in invaded ranges than in their native ranges. However,the mechanism mediating this phenotypic plasticity of fecundity of an invasive species remains poorly understood. Pinewood nematode (Bursaphelenchus xylophilus )is the causal agent for the destructive forest disease-pine wilt disease, which mainly feeds on its associated fungi and xylem. Three Ophiostomatoid fungi were isolated and identified in close association with reproduction of pinewood nematode, especially a native species, Sporothrix sp1, which is not reported in its native range North America. Our preliminary work indicated Diacetone alcohol (DAA) from host pine xylem induced by inoculation with Sporothrix sp.1 plays an important role in promoting the reproduction of the nematode.The objectives of this current proposal aim to study the mechanism of DAA on the fecundity of pinewood nematode by comparasion analysis of Chinese and American strains through laboratory bioassys coupled with transcriptome gene expression. The expected result will enable us to explain the invasiveness of pinewood nematode in viewpoint of nematode-fungi-pine trees interactions through this unique induced compound,DAA.