Microbial symbionts of herbivorous insects have been suggested to aid in the detoxification of plant defense compounds; however, quantitative studies on microbial contribution to plant toxin degradation remain scarce. Here, we demonstrate microbiome‐mediated degradation of plant‐derived toxic isothiocyanates in the cabbage stem flea beetle Psylliodes chrysocephala, a major pest of oilseed rape. Suppression of microbiota in antibiotic‐fed beetles resulted in up to 11.3‐fold higher levels of unmetabolized isothiocyanates compared to control beetles but did not affect other known detoxification pathways in P. chrysocephala. We characterized the microbiome of laboratory‐reared and field‐collected insects using 16S rRNA amplicon sequencing and isolated bacteria belonging to the three core genera Pantoea, Acinetobacter and Pseudomonas. Only Pantoea isolates rapidly degraded isothiocyanates in vitro, and restored isothiocyanate degradation in vivo when reintroduced in antibiotic‐fed beetles. Pantoea was consistently present across beetle life stages and in field and lab populations. In addition, Pantoea was detected in undamaged tissues of the host plant Brassica rapa, indicating that P. chrysocephala could possibly acquire an isothiocyanate detoxifying bacterium through their diet. Our results demonstrate that both insect endogenous mechanisms and the microbiota can contribute to the detoxification of plant defense compounds and together they can better account for the fate of ingested plant metabolites.

中文翻译：

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肠道菌群降解跳蚤甲虫害虫中的有毒异硫氰酸盐

草食性昆虫的微生物共生体被认为有助于植物防御化合物的解毒。然而，关于微生物对植物毒素降解的贡献的定量研究仍然很少。在这里，我们证明了甘蓝茎跳蚤甲虫Psylliodes chrysocephala（一种油菜的主要害虫）中由微生物组介导的植物源性有毒异硫氰酸盐的降解。与对照甲虫相比，抑制抗生素喂养的甲虫中的微生物群导致未代谢的异硫氰酸盐含量高出11.3倍，但不影响金黄色假单胞菌的其他已知排毒途径。我们使用16S rRNA扩增子测序和分离的细菌来表征实验室饲养和现场收集的昆虫的微生物组，该细菌属于三个主要属泛菌，不动杆菌和假单胞菌。O nly Pantoea可在体外分离迅速降解的异硫氰酸盐，并在重新引入抗生素饲喂的甲虫后可在体内恢复异硫氰酸盐的降解。成团泛菌是跨甲虫生活阶段和在现场和实验室的人群始终存在。此外，在寄主植物芸苔的未受损组织中检测到了泛菌，表明该菌是金头孢可以通过饮食获得异硫氰酸盐解毒细菌。我们的研究结果表明，昆虫的内源性机制和微生物区系都可以促进植物防御化合物的解毒，并且它们一起可以更好地说明摄入的植物代谢产物的命运。