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.

多种昆虫取食胁迫对植食性昆虫诱导的植物挥发物及捕食性节肢动物的影响正日益受到学界关注。植物病原物同样是植物面临的重要威胁，且植物针对病原物与昆虫的防御策略存在紧密关联，但病原物对昆虫诱导挥发物的潜在影响长期被大幅忽视，病原物的致病力程度也极少被纳入考量范畴。本研究探究了分别单独施加强致病力、弱致病力的野油菜黄单胞菌（Xanthomonas campestris）菌株，或是将其与菜粉蝶（Pieris brassicae）幼虫取食同时施加胁迫，对黑芥（Brassica nigra）植株挥发物释放的影响。随后进一步评估了这些挥发物对菜蛾盘绒茧蜂（Cotesia glomerata）寄生蜂觅食行为的作用。研究发现，病原物自身诱导产生的挥发物对寄生蜂具有极高的引诱活性，同时还能增强寄主植物被昆虫取食后挥发物的引诱效果。化学分析结果显示，强致病力与弱致病力菌株诱导产生的植物挥发物存在显著差异，其中倍半萜（sesquiterpene）、高萜烯（homoterpene）以及绿叶挥发物（green leaf volatile）类化合物是造成差异的主要组分。此外，强致病力菌株与菜粉蝶幼虫取食所诱导的挥发物混合物存在高度相似性。无论是强致病力还是弱致病力病原物的侵染，均会对植物化学特性及其与其他群落成员的互作关系产生显著影响，这表明整合病原物与昆虫相关的研究，有助于我们在日益复杂的环境条件下深化对植物防御机制的认知。