Department of Chemistry and Biomedical Sciences, Faculty of Health and Life Sciences, Linnaeus University, 382 91, Kalmar, Sweden.
Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology, 100 44, Stockholm, Sweden.
ISME J. 2019 Jun;13(6):1535-1545. doi: 10.1038/s41396-019-0370-7. Epub 2019 Feb 15.
Convergent evolution of semiochemical use in organisms from different Kingdoms is a rarely described phenomenon. Tree-killing bark beetles vector numerous symbiotic blue-stain fungi that help the beetles colonize healthy trees. Here we show for the first time that some of these fungi are able to biosynthesize bicyclic ketals that are pheromones and other semiochemicals of bark beetles. Volatile emissions of five common bark beetle symbionts were investigated by gas chromatography-mass spectrometry. When grown on fresh Norway spruce bark the fungi emitted three well-known bark beetle aggregation pheromones and semiochemicals (exo-brevicomin, endo-brevicomin and trans-conophthorin) and two structurally related semiochemical candidates (exo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane and endo-1,3-dimethyl-2,9-dioxabicyclo[3.3.1]nonane) that elicited electroantennogram responses in the spruce bark beetle Ips typographus. When grown on malt agar with C D-Glucose, the fungus Grosmannia europhioides incorporated C into exo-brevicomin and trans-conophthorin. The enantiomeric compositions of the fungus-produced ketals closely matched those previously reported from bark beetles. The production of structurally complex bark beetle pheromones by symbiotic fungi indicates cross-kingdom convergent evolution of signal use in this system. This signaling is susceptible to disruption, providing potential new targets for pest control in conifer forests and plantations.
来自不同生物界的生物体对半化学物质的趋同进化是一种很少被描述的现象。杀死树木的树皮甲虫携带许多共生的蓝变真菌，这些真菌帮助甲虫在健康的树上定殖。在这里，我们首次表明，这些真菌中的一些能够生物合成双环酮，这些酮是树皮甲虫的信息素和其他半化学物质。通过气相色谱-质谱法研究了五种常见的树皮甲虫共生真菌的挥发性排放物。当在新鲜挪威云杉树皮上生长时，真菌会释放出三种著名的树皮甲虫聚集信息素和半化学物质（外-短尾酮、内-短尾酮和反-康朴桐醇）以及两种结构上相关的半化学物质候选物（外-1,3-二甲基-2,9-二氧杂双环[3.3.1]壬烷和内-1,3-二甲基-2,9-二氧杂双环[3.3.1]壬烷），这些物质在云杉树皮甲虫 Ips typographus 中引起了触角电图反应。当在含有 C D-葡萄糖的麦芽琼脂上生长时，真菌 Grosmannia europhioides 将 C 掺入外-短尾酮和反-康朴桐醇中。真菌产生的酮的对映体组成与以前从树皮甲虫中报道的非常匹配。共生真菌产生结构复杂的树皮甲虫信息素表明，该系统中信号使用的趋同进化发生在跨生物界。这种信号容易受到干扰，为针叶林和人工林的害虫控制提供了新的潜在目标。
