Xu Yong-Jiang, Luo Feifei, Gao Qiang, Shang Yanfang, Wang Chengshu
Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200032, China.
Anal Bioanal Chem. 2015 Jun;407(16):4815-21. doi: 10.1007/s00216-015-8648-8. Epub 2015 Apr 21.
The interactions between insects and pathogenic fungi are complex. We employed metabolomic techniques to profile insect metabolic dynamics upon infection by the pathogenic fungus Beauveria bassiana. Silkworm larvae were infected with fungal spores and microscopic observations demonstrated that the exhaustion of insect hemocytes was coupled with fungal propagation in the insect body cavity. Metabolomic analyses revealed that fungal infection could significantly alter insect energy and nutrient metabolisms as well as the immune defense responses, including the upregulation of carbohydrates, amino acids, fatty acids, and lipids, but the downregulation of eicosanoids and amines. The insect antifeedant effect of the fungal infection was evident with the reduced level of maclurin (a component of mulberry leaves) in infected insects but elevated accumulations in control insects. Insecticidal and cytotoxic mycotoxins like oosporein and beauveriolides were also detected in insects at the later stages of infection. Taken together, the metabolomics data suggest that insect immune responses are energy-cost reactions and the strategies of nutrient deprivation, inhibition of host immune responses, and toxin production would be jointly employed by the fungus to kill insects. The data obtained in this study will facilitate future functional studies of genes and pathways associated with insect-fungus interactions.
昆虫与致病真菌之间的相互作用十分复杂。我们运用代谢组学技术来描绘感染致病真菌球孢白僵菌后昆虫的代谢动态。用真菌孢子感染家蚕幼虫，显微镜观察表明昆虫血细胞的耗尽与真菌在昆虫体腔内的繁殖相关联。代谢组学分析显示，真菌感染可显著改变昆虫的能量和营养代谢以及免疫防御反应，包括碳水化合物、氨基酸、脂肪酸和脂质的上调，但类二十烷酸和胺类的下调。真菌感染对昆虫的拒食作用明显，感染昆虫中桑色素（桑叶的一种成分）水平降低，而对照昆虫中积累增加。在感染后期的昆虫中还检测到了杀昆虫和细胞毒性霉菌毒素，如卵孢霉素和白僵菌素。综合来看，代谢组学数据表明昆虫免疫反应是耗能反应，真菌会联合采用营养剥夺、抑制宿主免疫反应和产生毒素的策略来杀死昆虫。本研究获得的数据将有助于未来对与昆虫 - 真菌相互作用相关的基因和途径进行功能研究。
