重大入侵种松材线虫竞争替代本地拟松材线虫的分子和化学通讯基础

The invasiveness of an invasive species is the key scientific question in invasion biology while most invasive species posseses propagation plasticity. In generally, invasive species has higher fecundity in invaded ranges than in their native ranges, together with other apparent competitive traits. However, there were many native cogeneric species sharing very similar biology traits with their invasive sibling species but do not cause any damage as pest, this is especially true with most invasive pest insects and diseasesCompetitive displacement has been reported in many cases of various invasive species However, the mechanism mediating this competitive displacement remains poorly understood. Pinewood nematode (Bursaphelenchus xylophilus), vectored by the cerambycid beetle, Monochamus alternatus, is the causal agent for the destructivepine wilt disease, which mainly feeds on its associated fungi and xylem. Bursaphelenchus mucronatus is a native slibling species, and widely occured in host pines in southern China. However, Bursaphelenchus mucronatus is gradually replaced by pinewood once it invades a new range, which leading to the mortality eventually. The objective of the current project focus on the mechanism mediating this competitive displacement through genetics, transcriptome gene expression analysis and chemical communications via a new pheromone-ascarosides which we recently identified both in pinewood nematode and its vector beetle, Monochamus alternatus. Preliminary work in my laboratory has shown that ascarosides not only coordinated pinewood nematode development with the life cycle of its vector beetle but also played a role in competition between Bursaphelenchus xylophilus and B. mucronatus. Knowledge of the molecular mechanism and chemical signals between those two sibling species in competition, and understanding of those interactions will enable us to explain the invasiveness of pinewood nematode from the point of view of competitive displacement. Furthermore, this knowledge has implications in interfering with the dispersal of this important plant-parasitic nematode in management.

外来入侵病虫害通常在原产地危害并不严重，到入侵地后却暴发成灾，这就是入侵种的入侵性——入侵生物学的核心科学问题。成功入侵的物种普遍具有繁殖和竞争力强的特性。而一些同域分布的本地近缘物种与入侵种的形态和生物学特性很相似，但不造成猖獗危害。甚至在与入侵种相遇时，本地近缘种会遭到入侵种的竞争替代。松材线虫作为世界性重大外来入侵种，入侵过程中繁殖和致病力增强，同时能够竞争替代掉本地近缘种拟松材线虫。但是，广泛存在的竞争替代现象背后的基因和化学信息调控机制尚不明确。本项目将通过化学生态和分子生物学手段研究：1、松材线虫与拟松材线虫繁殖和致病表型差异形成的分子适应机理；2、松材线虫与拟松材线虫竞争替代的化学信息调控机理。在分子和化学水平揭示起源于同一祖先的两个物种形成巨大表型差异的基因变异分子基础和竞争替代现象的化学及其化感受体表达调控基础。从竞争替代角度阐明松材线虫的入侵和成灾机制。

松材线虫作为世界性重大外来入侵种，入侵过程中繁殖和致病力增强，同时能够竞争替代掉本地近缘种拟松材线虫。但是，广泛存在的竞争替代现象背后的基因和化学信息调控机制尚不明确。本项目取得的重要研究成果有：（1）构建了拟松材线虫染色体水平的基因组；（2）解析了松材线虫入侵过程中的基因变异，揭示了松材线虫寄主适应的分子机制；（3）揭示了细菌调控的松材线虫的免疫逃避机制；（4）阐明了氧化应激能力的增强促进松材线虫的致病性和繁殖力；（5）阐明了ascaroside介导的松材线虫竞争替代拟松材线虫的化学机制；（6）揭示了ascarosides调控的松材线虫繁殖可塑性；（7）阐明了Ascaroside促进蓝变菌发生及松材线虫病的爆发成灾机制。本项目揭示了松材线虫竞争替代拟松材线虫的分子和化学机制，从竞争替代角度阐明了松材线虫的入侵和成灾机制。