Wybouw Nicky, Zhurov Vladimir, Martel Catherine, Bruinsma Kristie A, Hendrickx Frederik, Grbić Vojislava, Van Leeuwen Thomas
Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 9424, 1090 GE, Amsterdam, The Netherlands.
Department of Biology, University of Western Ontario, London, N6A 5B7, ON, Canada.
Mol Ecol. 2015 Sep;24(18):4647-63. doi: 10.1111/mec.13330. Epub 2015 Sep 3.
Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genomewide transcriptional changes in both spider mite and tomato as a consequence of mite's adaptation to tomato. We transferred a genetically diverse mite population from bean to tomato where triplicated populations were allowed to propagate for 30 generations. Evolving populations greatly increased their reproductive performance on tomato relative to their progenitors when reared under identical conditions, indicative of genetic adaptation. Analysis of transcriptional changes associated with mite adaptation to tomato revealed two main components. First, adaptation resulted in a set of mite genes that were constitutively downregulated, independently of the host. These genes were mostly of an unknown function. Second, adapted mites mounted an altered transcriptional response that had greater amplitude of changes when re-exposed to tomato, relative to nonadapted mites. This gene set was enriched in genes encoding detoxifying enzymes and xenobiotic transporters. Besides the direct effects on mite gene expression, adaptation also indirectly affected the tomato transcriptional responses, which were attenuated upon feeding of adapted mites, relative to the induced responses by nonadapted mite feeding. Thus, constitutive downregulation and increased transcriptional plasticity of genes in a herbivore may play a central role in adaptation to host plants, leading to both a higher detoxification potential and reduced production of plant defence compounds.
多食性节肢动物食草动物能迅速适应多种寄主植物。然而，与适应相关的食草动物及其寄主的转录重编程程度仍知之甚少。我们以二斑叶螨（Tetranychus urticae）和番茄为模型，利用现有的基因组资源，研究了叶螨适应番茄后，叶螨和番茄在全基因组水平上的相互转录变化。我们将一个基因多样化的叶螨种群从豆类转移到番茄上，让三个重复的种群繁殖30代。在相同条件下饲养时，进化后的种群相对于其祖先，在番茄上的繁殖性能大幅提高，这表明发生了遗传适应。对与叶螨适应番茄相关的转录变化分析揭示了两个主要成分。首先，适应导致了一组叶螨基因的组成性下调，与寄主无关。这些基因大多功能未知。其次，适应后的叶螨表现出改变的转录反应，相对于未适应的叶螨，再次接触番茄时变化幅度更大。这个基因集富含编码解毒酶和外源性转运蛋白的基因。除了对叶螨基因表达的直接影响外，适应还间接影响了番茄的转录反应，相对于未适应叶螨取食诱导的反应，适应叶螨取食后番茄的转录反应减弱。因此，食草动物中基因的组成性下调和转录可塑性增加可能在适应寄主植物中起核心作用，导致更高的解毒潜力和植物防御化合物产量降低。
