Department of Biological Sciences, University of Toronto Scarborough, Toronto, M1C 1A4, Canada.
Department of Cell and Systems Biology, University of Toronto, Toronto, M5S 3G5, Canada.
Sci Rep. 2023 Oct 24;13(1):18139. doi: 10.1038/s41598-023-44938-2.
Plants protect their tissues from insect herbivory with specialized structures and chemicals, such as cuticles, trichomes, and metabolites contained therein. Bacteria inside the insect gut are also exposed to plant defences and can potentially modify the outcome of plant-insect interactions. To disentangle this complex multi-organism system, we used tomato mutants impaired in the production of plant defences (odorless-2 and jasmonic acid-insensitive1) and two cultivars (Ailsa Craig and Castlemart), exposed them to herbivory by the cabbage looper (Trichoplusia ni H.) and collected the insect frass for bacterial community analysis. While the epicuticular wax and terpene profiles were variable, the leaf fatty acid composition remained consistent among genotypes. Moreover, larval weight confirmed the negative association between plant defences and insect performance. The distinctive frass fatty acid profiles indicated that plant genotype also influences the lipid digestive metabolism of insects. Additionally, comparisons of leaf and insect-gut bacterial communities revealed a limited overlap in bacterial species between the two sample types. Insect bacterial community abundance and diversity were notably reduced in insects fed on the mutants, with Enterobacteriaceae being the predominant group, whereas putatively pathogenic taxa were found in wildtype genotypes. Altogether, these results indicate that plant defences can modulate insect-associated bacterial community composition.
植物利用特殊的结构和化学物质来保护其组织免受昆虫的侵害，如角质层、毛状体和其中包含的代谢物。昆虫肠道内的细菌也会接触到植物防御系统，并可能改变植物-昆虫相互作用的结果。为了理清这个复杂的多器官系统，我们使用了番茄防御机制受损的突变体（odorless-2 和 jasmonic acid-insensitive1）和两个品种（Ailsa Craig 和 Castlemart），让它们受到小菜蛾（Trichoplusia ni H.）的侵害，并收集昆虫粪便进行细菌群落分析。虽然表皮蜡质和萜烯谱是可变的，但叶片脂肪酸组成在基因型之间保持一致。此外，幼虫体重证实了植物防御与昆虫表现之间的负相关关系。独特的粪便脂肪酸谱表明，植物基因型也会影响昆虫的脂质消化代谢。此外，叶片和昆虫肠道细菌群落的比较表明，两种样本类型之间的细菌物种重叠有限。喂食突变体的昆虫中，昆虫肠道细菌群落的丰度和多样性显著降低，肠杆菌科是主要群体，而在野生型基因型中则发现了潜在的病原类群。总的来说，这些结果表明，植物防御可以调节昆虫相关的细菌群落组成。
