Effects of nitric oxide, spermidine, and salicylic acid signaling and their crosstalk with each other in the production of commercially important stevioside content and drought stress responses in Stevia rebaudiana bertoni

Abstract

The leaves of Stevia rebaudiana Bertoni contain steviol glycosides (SGs), which provide the sweet taste of stevia. However, drought can have a negative impact on the plant's growth and development. To address this issue, signaling molecules such as sodium nitroprusside (SNP), spermidine (SPD), and salicylic acid (SA) are often applied to increase plant tolerance. However, the combined effects of these molecules have not been extensively studied. This research aimed to investigate the effects of controlled elicitation with SA, SNP, SPD, and their combinations on plant performance, SG content, and drought stress mitigation in Stevia rebaudiana under drought stress. The elicitor treatments were found to result in a significant increase in SG content, with 0.1 mM SA being the most effective treatment. Additionally, the treatments were able to reduce the stress effects on growth parameters to non-stress levels. The use of SPD, SA+SNP, and SPD+SNP on stressed plants significantly increased CAT and SOD activity, resulting in a more active antioxidant defense system that lowered MDA contents and H2O2 generation. These findings suggest that stevia cultivation with controlled elicitation could be used to improve plant growth, tolerance, and SG production under drought stress conditions.