Data from: Compatible and incompatible pathogen-plant interactions differentially affect plant volatile emissions and the attraction of parasitoid wasps

The effects of multiple insect attacks on herbivore-induced plant volatiles and carnivorous arthropods are increasingly studied. Phytopathogens also represent an important threat to plants, and plant defense strategies against pathogens and insects are strongly interconnected, yet the potential impact of pathogens on insect-induced volatiles has been largely overlooked, and degree of pathogenicity rarely considered. We investigated how pathogen challenge, with virulent and avirulent strains of Xanthomonas campestris either alone or with simultaneous Pieris brassicae caterpillar herbivory, affected the volatile emissions of Brassica nigra plants. The impact of these volatiles on the foraging behavior of Cotesia glomerata parasitoids was then assessed. Pathogens themselves induced volatiles that were highly attractive to parasitoids, and enhanced the attractiveness of host-infested plant volatiles. Chemical analyses revealed that virulent and avirulent strains differentially induced plant volatiles, with primarily sesquiterpene, homoterpene and green leaf volatile compounds contributing to the differences. Strong similarities were found in the blends induced by the virulent strain and caterpillar herbivory. Challenge by either virulent or avirulent pathogens has a significant impact on plant chemistry and its interactions with other community members, demonstrating the importance of integrating pathogen- and insect-based research to broaden our knowledge of plant defenses under conditions of increasing complexity.

多种昆虫取食对植食性昆虫诱导的植物挥发物(herbivore-induced plant volatiles)与肉食性节肢动物的影响，正日益受到学界的关注。植物病原物亦是植物的重要胁迫因子，植物针对病原物与昆虫的防御策略存在紧密的交互关联，然而病原物对昆虫诱导植物挥发物的潜在影响却长期被极大忽视，且病原物的致病力水平也极少被纳入研究范畴。本研究以黑芥(Brassica nigra)为材料，探究了分别接种强毒株与无毒菌株的野油菜黄单胞菌(Xanthomonas campestris)，以及该病原物与大菜粉蝶(Pieris brassicae)幼虫同时取食的双重处理对植株挥发物释放的影响，并进一步评估了这些挥发物对菜粉蝶盘绒茧蜂(Cotesia glomerata)寄生蜂觅食行为的调控作用。研究结果显示，病原物自身诱导产生的挥发物对寄生蜂具有极强的引诱活性，同时还能提升被目标寄主昆虫取食的植物挥发物的吸引效能。化学分析表明，强毒株与无毒菌株可差异性诱导植物挥发物的合成，其中倍半萜、高萜烯与绿叶挥发物(green leaf volatile)是导致挥发物组分差异的核心物质。此外，强毒株诱导的挥发物组分与幼虫取食诱导的挥发物组分具有高度相似性。无论是接种强毒还是无毒病原物，均会显著改变植物的化学防御特征及其与群落其他成员的互作关系，这表明整合病原物与昆虫相关的植物防御研究，有助于在日益复杂的生态背景下深化我们对植物防御机制的认知。