Actin remodelling by a membrane-associated oxidative process can sense perturbations of membrane integrity and activate defence. In the current work, we show that glycyrrhizin, a muscle relaxant used in Traditional Chinese Medicine, can activate oxidative burst and actin remodelling in tobacco BY-2 cells, which could be suppressed by diphenylene iodonium, an inhibitor of NADPH oxidases. Glycyrrhizin caused a dose-dependent delay of proliferation, and induced cell death, which was suppressed by addition of indole-acetic acid, a natural auxin that can mitigate RboH dependent actin remodelling. To test, whether the actin remodelling induced by glycyrrhizin was followed by activation of defence, several events of basal immunity were probed. We found that glycyrrhizin induced a transient extracellular alkalinisation, indicative of calcium influx. Furthermore, transcripts of phytoalexins genes, were activated in cells of the grapevine Vitis rupestris, and this induction was followed by accumulation of the glycosylated stilbene α-piceid. We also observed that glycyrrhizin was able to induce actin bundling in leaves of a transgenic grape, especially in guard cells. We discuss these data in frame of a model, where glycyrrhizin, through stimulation of RboH, can cause actin remodelling, followed by defence responses, such as calcium influx, induction of phytoalexins transcripts, and accumulation of stilbene glycosides.

中文翻译：

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甘草甜素是中药甘草的活性化合物，可刺激葡萄肌动蛋白重塑和防御


通过膜相关氧化过程进行的肌动蛋白重塑可以感知膜完整性的扰动并激活防御。在目前的工作中，我们发现甘草甜素（一种中药中使用的肌肉松弛剂）可以激活烟草 BY-2 细胞中的氧化爆发和肌动蛋白重塑，而这种作用可以被 NADPH 氧化酶抑制剂二亚苯基碘鎓抑制。甘草甜素引起剂量依赖性的增殖延迟，并诱导细胞死亡，通过添加吲哚乙酸（一种天然生长素，可以减轻 RboH 依赖性肌动蛋白重塑）来抑制细胞死亡。为了测试甘草甜素诱导的肌动蛋白重塑是否随后激活防御，对基础免疫的几个事件进行了探测。我们发现甘草酸诱导短暂的细胞外碱化，表明钙内流。此外，植物抗毒素基因的转录本在葡萄树葡萄细胞中被激活，并且这种诱导之后是糖基化二苯乙烯α-云杉苷的积累。我们还观察到，甘草甜素能够诱导转基因葡萄叶子中的肌动蛋白成束，特别是在保卫细胞中。我们在模型框架中讨论这些数据，其中甘草甜素通过刺激 RboH 可以引起肌动蛋白重塑，然后发生防御反应，例如钙内流、植物抗毒素转录物的诱导和二苯乙烯糖苷的积累。