Mithöfer A, Reichelt M, Nakamura Y
Department Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Jena, Germany.
Plant Biol (Stuttg). 2014 Sep;16(5):982-7. doi: 10.1111/plb.12148. Epub 2014 Feb 5.
Carnivorous sundew plants catch and digest insect prey for their own nutrition. The sundew species Drosera capensis shows a pronounced leaf bending reaction upon prey capture in order to form an 'outer stomach'. This formation is triggered by jasmonates, phytohormones typically involved in defence reactions against herbivory and wounding. Whether jasmonates still have this function in D. capensis in addition to mediating the leaf bending reaction was investigated here. Wounded, insect prey-fed and insect-derived oral secretion-treated leaves of D. capensis were analysed for jasmonates (jasmonic acid, JA; jasmonic acid-isoleucine conjugate, JA-Ile) using LC-MS/MS. Prey-induced jasmonate accumulation in D. capensis leaves was persistent, and showed high levels of JA and JA-Ile (575 and 55.7 pmol · g · FW(-1) , respectively), whereas wounding induced a transient increase of JA (maximum 500 pmol · g · FW(-1) ) and only low (3.1 pmol · g · FW(-1) ) accumulation of JA-Ile. Herbivory, mimicked with a combined treatment of wounding plus oral secretion (W+OS) obtained from Spodoptera littoralis larvae induced both JA (4000 pmol · g · FW(-1) ) and JA-Ile (25 pmol · g · FW(-1) ) accumulation, with kinetics similar to prey treatment. Only prey and W+OS, but not wounding alone or OS, induced leaf bending. The results indicate that both mechanical and chemical stimuli trigger JA and JA-Ile synthesis. Differences in kinetics and induced jasmonate levels suggest different sensing and signalling events upon injury and insect-dependent challenge. Thus, in Drosera, jasmonates are still part of the response to wounding. Jasmonates are also employed in insect-induced reactions, including responses to herbivory and carnivory.
食虫茅膏菜植物捕捉并消化昆虫猎物以获取自身营养。海角茅膏菜（Drosera capensis）在捕获猎物时会表现出明显的叶片弯曲反应，以形成一个“外部胃”。这种形成是由茉莉酸盐触发的，茉莉酸盐是一类通常参与植物对草食动物和伤口防御反应的植物激素。本文研究了茉莉酸盐在海角茅膏菜中除了介导叶片弯曲反应外是否仍具有此功能。使用液相色谱-串联质谱法（LC-MS/MS）分析了海角茅膏菜受伤、喂食昆虫猎物以及用昆虫来源的口腔分泌物处理的叶片中的茉莉酸盐（茉莉酸，JA；茉莉酸异亮氨酸共轭物，JA-Ile）。猎物诱导的海角茅膏菜叶片中茉莉酸盐的积累是持续的，并且显示出高水平的JA和JA-Ile（分别为575和55.7 pmol·g·FW⁻¹），而伤口诱导JA出现短暂增加（最大值为500 pmol·g·FW⁻¹），且JA-Ile的积累量很低（3.1 pmol·g·FW⁻¹）。用斜纹夜蛾幼虫的伤口加口腔分泌物联合处理（W + OS）模拟草食动物取食，诱导了JA（4000 pmol·g·FW⁻¹）和JA-Ile（25 pmol·g·FW⁻¹）的积累，其动力学与猎物处理相似。只有猎物和W + OS能诱导叶片弯曲，而单独的伤口或口腔分泌物则不能。结果表明，机械和化学刺激均能触发JA和JA-Ile的合成。动力学和诱导的茉莉酸盐水平的差异表明，在受伤和昆虫依赖性挑战时存在不同的感知和信号传导事件。因此，在茅膏菜中，茉莉酸盐仍然是对伤口反应的一部分。茉莉酸盐也用于昆虫诱导的反应，包括对草食动物和肉食动物的反应。
