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及肉食性节肢动物的影响，正受到日益广泛的研究关注。植物病原微生物同样是植物的重要威胁之一，植物针对病原与昆虫的防御策略存在紧密关联，但病原对昆虫诱导挥发物的潜在影响长期以来被极大忽视，病原致病力的差异也极少被纳入研究考量。本研究探究了单独接种强致病力与弱致病力的野油菜黄单胞菌（Xanthomonas campestris）菌株，或是联合大菜粉蝶（Pieris brassicae）幼虫取食，对黑芥（Brassica nigra）植株挥发物释放的影响，并进一步评估了这些挥发物对菜绒茧蜂（Cotesia glomerata）寄生蜂觅食行为的作用。研究发现，病原微生物本身即可诱导产生对寄生蜂极具吸引力的挥发物，同时还能增强寄主植物被昆虫取食后挥发物的吸引能力。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、高萜烯类化合物以及绿叶挥发物是造成差异的主要成分。强致病力菌株诱导的挥发物混合物与大菜粉蝶幼虫取食诱导的挥发物混合物具有高度相似性。无论是强致病力还是弱致病力的病原侵染，均会对植物化学组成及其与其他群落成员的互作产生显著影响，这表明整合病原相关与昆虫相关的研究，有助于我们在日益复杂的环境中深化对植物防御机制的认知。