Counteradaptations of chrysomelid beetles to host plant defences over the ontogeny from larvae to adults

叶甲虫对宿主植物从幼虫到成虫个体发育防御的反适应

• 批准号: 315499861
• 负责人: Professorin Dr. Caroline Müller
• 金额: --
• 依托单位: Arbeitsgruppe Chemische Ökologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/315499861?language=en
• 关键词: Counteradaptations; chrysomelid; beetles; host; plant

Herbivorous insects have evolved various strategies to deal with the defences of their host plants. The plant family of Brassicaceae is well known for its glucosinolate-myrosinase defence system, in which toxic hydrolysis products such as isothiocyanates are formed once the substrate comes into contact with the myrosinase enzymes. Thus, insects feeding on Brassicaceae must metabolise the glucosinolates in a way that they avoid the formation of toxic breakdown products. A fascinating diversity of insect counteradaptations to the plant defence system has been revealed within the Lepidoptera, and in species of Hemiptera, Hymenoptera and one Coleoptera. In contrast, almost nothing is known about the detoxification of the glucosinolate-myrosinase system in different developmental stages of species such as chrysomelid beetles, in which both larvae and adults feed on leaves of Brassicaceae. Preliminary experiments indicate that the specialist chrysomelid Phaedon cochleariae uses a novel mechanism of dealing with the glucosinolate-myrosinase system which is distinct from all counteradaptations that have been discovered for other Brassicaceae-feeders. In this project, I aim to investigate the glucosinolate metabolism of two chrysomelid species, the mentioned specialist and a generalist, over ontogeny. Larvae versus adults will be studied to test whether the detoxification of the dual defence may differ between stages because of the major physiological reorganisation during metamorphosis. Furthermore, I aim to study the specificity of glucosinolate metabolism with regard to the different structures of glucosinolates. To answer these questions, feeding experiments will be carried out with labelled and unlabelled glucosinolates followed by chemical analysis of breakdown products. Additionally, imaging of sections of larvae and adults, taken after different feeding durations, using matrix assisted laser desorption ionisation-mass spectrometry imaging (MALDI-MSI) will reveal the localisation of intact glucosinolates and their metabolites in the insects, allowing to identify the speed with which glucosinolates are metabolised as well as the organs in which metabolism takes place. Finally, measurements of myrosinase activities in gut sections will reveal whether these enzymes are inhibited during the passage through the gut in larvae or adults. From the herbivore perspective, the results of the project will reveal novel insight in the impressive divergent evolution of insect adaptations to this dual plant defence system and will demonstrate in how far these adaptations change over ontogeny. From a plant evolutionary perspective, we may learn in how far the insect processing of different glucosinolates and dealing with the myrosinases may lead to the fact that plants synthesise such a large variety of glucosinolate structures and glucosinolate hydrolysis products.

食草昆虫已经进化出各种策略来对付寄主植物的防御。十字花科植物家族以其硫代葡萄糖苷-黑芥子酶防御系统而闻名，一旦底物与黑芥子酶接触，就会形成有毒的水解产物，如异硫氰酸酯。因此，以十字花科植物为食的昆虫必须以一种避免形成有毒分解产物的方式代谢硫代葡萄糖苷。在鳞翅目、半翅目、膜翅目和鞘翅目物种中，揭示了昆虫对抗植物防御系统的迷人多样性。相比之下，对于不同发育阶段的物种，如金体甲虫，其幼虫和成虫都以十字花科植物的叶子为食，其硫代葡萄糖苷-黑芥子酶系统的解毒作用几乎一无所知。初步实验表明，特殊的金玉体耳蜗Phaedon使用一种新的机制来处理硫代葡萄糖苷-黑芥子酶系统，这种机制不同于其他芸苔科捕食者所发现的所有反适应。在这个项目中，我的目的是研究两种染色体的硫代葡萄糖苷代谢，上述的专家和一个通才，在个体发生。将对幼虫和成虫进行研究，以测试双重防御的解毒能力是否会因变态过程中主要的生理重组而在不同阶段有所不同。此外，我的目的是研究不同结构的硫代葡萄糖苷代谢的特异性。为了回答这些问题，将对标记和未标记的硫代葡萄糖苷进行饲养实验，然后对分解产物进行化学分析。此外，使用基质辅助激光解吸电离-质谱成像（MALDI-MSI）对不同摄食时间后的幼虫和成虫切片进行成像，将揭示完整的硫代葡萄糖苷及其代谢物在昆虫体内的定位，从而确定硫代葡萄糖苷代谢的速度以及代谢发生的器官。最后，测量肠道部分的黑芥子酶活性将揭示这些酶在幼虫或成虫通过肠道时是否受到抑制。从食草动物的角度来看，该项目的结果将揭示昆虫适应这种双重植物防御系统的令人印象深刻的不同进化的新见解，并将证明这些适应在个体发生过程中的变化程度。从植物进化的角度来看，我们可以了解到昆虫对不同硫代葡萄糖苷的加工和对芥子酸酶的处理在多大程度上可能导致植物合成如此多种类的硫代葡萄糖苷结构和硫代葡萄糖苷水解产物。