Department of Evolutionary and Population Biology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, B-9000 Ghent, Belgium.
Int J Mol Sci. 2018 Oct 20;19(10):3265. doi: 10.3390/ijms19103265.
Tomato plants are attacked by diverse herbivorous arthropods, including by cell-content-feeding mites, such as the extreme generalist and specialists like and . Mite feeding induces plant defense responses that reduce mite performance. However, and suppress plant defenses via poorly understood mechanisms and, consequently, maintain a high performance on tomato. On a shared host, can be facilitated by either of the specialist mites, likely due to the suppression of plant defenses. To better understand defense suppression and indirect plant-mediated interactions between herbivorous mites, we used gene-expression microarrays to analyze the transcriptomic changes in tomato after attack by either a single mite species (, , ) or two species simultaneously ( plus or plus ). Additionally, we assessed mite-induced changes in defense-associated phytohormones using LC-MS/MS. Compared to non-infested controls, jasmonates (JAs) and salicylate (SA) accumulated to higher amounts upon all mite-infestation treatments, but the response was attenuated after single infestations with defense-suppressors. Strikingly, whereas 8 to 10% of tomato genes were differentially expressed upon single infestations with or , respectively, only 0.1% was altered in -infested plants. Transcriptome analysis of dual-infested leaves revealed that primarily suppressed -induced JA defenses, while dampened -triggered host responses on a transcriptome-wide scale. The latter suggests that not solely down-regulates plant gene expression, but rather directs it back towards housekeeping levels. Our results provide valuable new insights into the mechanisms underlying host defense suppression and the plant-mediated facilitation of competing herbivores.
番茄植株受到多种取食植物组织的节肢动物的侵害，包括细胞内容物取食的螨类，如极端泛化种 和专食种 和 。螨类取食会诱导植物防御反应，从而降低螨类的取食作用。然而， 和 通过尚未完全了解的机制抑制植物防御，因此在番茄上仍保持高的取食作用。在共享的宿主上， 可能会被专食种中的任何一种促进，可能是由于植物防御的抑制。为了更好地理解防御抑制和取食植物的植食性螨之间的间接相互作用，我们使用基因表达微阵列分析了番茄在单一螨种（ 、 、 ）或两种螨同时取食（ 加 或 加 ）后转录组的变化。此外，我们还使用 LC-MS/MS 评估了防御相关植物激素的螨诱导变化。与未受侵染的对照相比，茉莉酸（JAs）和水杨酸（SA）在所有螨类侵染处理后积累量更高，但在防御抑制剂单一侵染后反应减弱。引人注目的是，虽然单一侵染 或 分别导致 8%到 10%的番茄基因差异表达，但 -侵染的植物中只有 0.1%的基因发生改变。双侵染叶片的转录组分析表明， 主要抑制 -诱导的 JA 防御，而 则在全转录组范围内减弱 -触发的宿主反应。后一种情况表明， 不仅下调植物基因表达，而且将其重新定向到维持细胞基本功能的水平。我们的研究结果为宿主防御抑制和竞争植食性螨的植物介导促进的机制提供了有价值的新见解。
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