Induced plant defense via volatile production is dependent on rhizobial symbiosis
Induced plant defense via volatile production is dependent on rhizobial symbiosis
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DOI：
10.1007/s00442-012-2539-x
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发表时间：
2013-07-01
期刊：
影响因子：
2.7
通讯作者：
Schaedler, Martin
中科院分区：
文献类型：
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作者：
Ballhorn, Daniel J.;Kautz, Stefanie;Schaedler, Martin
固氮根瘤菌可以通过改变植物的化学成分和食物质量来显著影响植物与食草动物的相互作用。然而，根瘤菌对植物挥发物的影响仍未被研究，而植物挥发物是对节肢动物草食动物的间接和直接防御，也是防御相关的植物-植物和植物内信号的信号。我们测定了茉莉酸(JA)诱导的根瘤菌定植和非根瘤菌利马豆(Fabaceae：Phaseolus Lunatus L.)挥发物的释放。并在嗅觉仪选择试验中测试了它们各自的挥发性有机化合物(VOC)花束对一种专业食草性昆虫(墨西哥豆甲；瓢虫科：变种瓢虫科)的影响。在进一步的实验中，我们发现JA诱导的VOC反映了植物对机械伤害和昆虫食草性的反应。经茉莉酸诱导后，根瘤菌植株显著释放更多的莽草酸衍生化合物，而通过十八烷类、甲氧戊酸和非甲氧戊酸途径产生的化合物的释放减少。这些变化影响了甲虫的选择行为，因为对被根瘤菌侵染的植物来说，非诱导植物的偏好更加明显。我们表明，吲哚可能是茉莉酸诱导的利马豆根瘤菌植株的挥发性有机物的驱避效应的起因。我们的研究证明了根瘤菌通过挥发物诱导植物防御的有效性。由于这些发现，我们将根瘤菌解释为豆类抵御食草动物的防御系统的组成部分。
Nitrogen-fixing rhizobia can substantially influence plant-herbivore interactions by altering plant chemical composition and food quality. However, the effects of rhizobia on plant volatiles, which serve as indirect and direct defenses against arthropod herbivores and as signals in defense-associated plant-plant and within-plant signaling, are still unstudied. We measured the release of jasmonic acid (JA)-induced volatiles of rhizobia-colonized and rhizobia-free lima bean plants (Fabaceae: Phaseolus lunatus L.) and tested effects of their respective bouquets of volatile organic compounds (VOCs) on a specialist insect herbivore (Mexican bean beetle; Coccinellidae: Epilachna varivestis Mulsant) in olfactometer choice trials. In a further experiment, we showed that VOC induction by JA reflects the plant responses to mechanical wounding and insect herbivory. Following induction with JA, rhizobia-colonized plants released significantly higher amounts of the shikimic acid-derived compounds, whereas the emission of compounds produced via the octadecanoid, mevalonate and non-mevalonate pathways was reduced. These changes affected the choice behavior of beetles as the preference of non-induced plants was much more pronounced for plants that were colonized by rhizobia. We showed that indole likely represents the causing agent for the observed repellent effects of jasmonic acid-induced VOCs of rhizobia-colonized lima bean plants. Our study demonstrates a rhizobia-triggered efficacy of induced plant defense via volatiles. Due to these findings, we interpret rhizobia as an integral part of legume defenses against herbivores.