S. rebaudiana is a sought after sweetener because of its low-calorie properties. However, the supply of suitable quantities of high quality propagation material is limited by inefficient propagation methods using conventional strategies. In vitro techniques combined with nanotechnology tools offer an attractive alternative not only for improved propagation but also for the stimulation of secondary metabolites which represent the targeted sweetener product for this crop. This report provides an evaluation of silver nanoparticles applied in temporary immersion bioreactors for the abovementioned purpose. Different levels of AgNPs were supplied (0.0—37.5 mg/L) and after 21 d of growth, morphological and biochemical indicators were evaluated. Silver nanoparticles at 25 and 37.5 mg/L decreased shoot multiplication rate, shoot length, and the number of nodes and leaves per shoot compared with the control while no adverse effect was found at the lower tested concentration (12.5 mg/L). Shoot fresh and dry weights also showed statistically significant differences. Regarding the biochemical phenotypes, chlorophyll a, carotenoids and soluble phenolics were increased in plants supplied with 25 mg/L AgNPs, with the latter two indicators suggesting oxidative stress. Interestingly, endogenous levels of diterpenes were significantly increased with the application of 12.5 mg/L AgNPs. It is suggested that AgNPs show potential to act as elicitors to promote the production of diterpenes in stevia but that further work is required to understand the balance between oxidative damage and secondary metabolite production and that optimization of the protocol is required to improve the propagation potential of this strategy.

甜叶菊由于其低热量特性，是一种广受欢迎的甜味剂。然而，适量的高质量繁殖材料的供应受到使用传统策略的低效繁殖方法的限制。体外技术与纳米技术工具相结合提供了一种有吸引力的替代方案，不仅可以改善繁殖，还可以刺激代表该作物目标甜味剂产品的次级代谢产物。本报告对用于上述目的的临时浸没式生物反应器中的银纳米粒子进行了评估。提供不同水平的 AgNPs (0.0-37.5 mg/L)，在生长 21 天后，评估形态学和生化指标。25 和 37.5 mg/L 的银纳米粒子降低了枝条增殖率、枝条长度、与对照相比，每根枝条的节和叶数，而在较低的测试浓度（12.5 mg/L）下没有发现不利影响。芽的鲜重和干重也显示出统计学上的显着差异。关于生化表型，叶绿素 a、类胡萝卜素和可溶性酚类物质在供应 25 mg/L AgNPs 的植物中增加，后两个指标表明存在氧化应激。有趣的是，随着 12.5 mg/L AgNP 的应用，二萜的内源性水平显着增加。