Yamasaki Yukiyo, Sumioka Hiroka, Takiguchi Mayu, Uemura Takuya, Kihara Yuka, Shinya Tomonori, Galis Ivan, Arimura Gen-Ichiro
Department of Biological Science and Technology, Faculty of Advanced Engineering, Tokyo University of Science, Tokyo, 125-8585, Japan.
Institute of Plant Science and Resources (IPSR), Okayama University, Kurashiki, 710-0046, Japan.
New Phytol. 2021 Sep;231(5):2029-2038. doi: 10.1111/nph.17444. Epub 2021 Jun 26.
A vast array of herbivorous arthropods live with symbiotic microorganisms. However, little is known about the nature and functional mechanism of bacterial effects on plant defense responses towards herbivores. We explored the role of microbes present in extracts of oral secretion (OS) isolated from larvae of Spodoptera litura, a generalist herbivore, in phytohormone signaling-dependent defense responses in Arabidopsis thaliana (Arabidopsis). In response to mechanical damage (MD) with application of bacteria-free OS (OS ) prepared by sterilization or filtration of OS, Arabidopsis leaves exhibited enhanced de novo synthesis of oxylipins, and induction of transcript abundance of the responsible genes, in comparison to those in leaves with MD + nonsterilized OS (OS ), indicating that OS bacteria serve as suppressors of these genes. By contrast, de novo synthesis/signaling of salicylic acid and signaling of abscisic acid were enhanced by OS bacteria. These signaling networks were cross-regulated by each other. Meta-analysis of OS bacteria identified 70 bacterial strains. Among them was Staphylococcus epidermidis, an anaerobic staphylococcus that was shown to contribute to the suppression/manipulation of phytohormone-dependent plant defense signaling. The presence of OS bacteria was consequently beneficial for S. litura larvae hosted by Brassicaceae.
大量食草节肢动物与共生微生物共生。然而，关于细菌对植物针对食草动物的防御反应的影响的性质和作用机制，我们了解得还很少。我们探究了从多食性食草动物斜纹夜蛾幼虫分离的口腔分泌物（OS）提取物中存在的微生物在拟南芥中依赖植物激素信号的防御反应中的作用。与受到机械损伤（MD）并施加经灭菌或过滤制备的无菌OS（OS）的叶片相比，受到MD并施加未灭菌OS（OS）的拟南芥叶片表现出氧脂类从头合成增强，以及相关基因转录丰度的诱导，这表明OS细菌是这些基因的抑制因子。相比之下，OS细菌增强了水杨酸的从头合成/信号传导以及脱落酸的信号传导。这些信号网络相互交叉调节。对OS细菌的荟萃分析鉴定出70种细菌菌株。其中包括表皮葡萄球菌，一种厌氧葡萄球菌，已证明它有助于抑制/操纵依赖植物激素的植物防御信号传导。因此，OS细菌的存在对十字花科植物上的斜纹夜蛾幼虫有益。
