The effects of exogenously applied antioxidants on plant growth and resilience

Abstract

Plant growth and resilience require balancing an inherently oxidative metabolism with powerful antioxidant systems that help maintain homeostasis. When the environment changes, reactive oxygen species are potent indicators of that change, allowing adaptation through re-balancing metabolism and antioxidant systems. A large body of evidence supports the use of exogenously applied antioxidants to improve both plant growth and their resilience to stress. Notably, some phenotypic effects are similar upon the application of chemically diverse antioxidants, while others are distinct. In this review, we analyze research from antioxidant treatment experiments and highlight the similarities in their practical applications and their effects on plant stress tolerance, photosynthesis, native antioxidant systems, and phytohormones. We also briefly cover the specific effects of individually applied antioxidants and what is known about their potential modes of action. Given the strong potential of antioxidant applications, we discuss research needed to promote their agricultural use. Finally, we identify outstanding questions about how the exogenous application of antioxidants mechanistically affects plant growth.

Is the application of bioactive anti‐stress substances with a seaweed‐derived biostimulant effective under adequate growth conditions?

“…In plants grown under optimal conditions, these effects have not been very evident, and even negative responses have been observed, reducing plant growth. For instance, in Arabidopsis thaliana , Pistacia vera , Malus domestica , Prunus avium , and Beta vulgaris plants, the application of these compounds under normal growth conditions decreased plant growth (Rodrigues de Queiroz et al 2023). Our results confirm these observations, suggesting that under adequate growth conditions without the presence of any type of stress, the application of Cytolan® Stress at high doses would eliminate the biostimulant effect of this product; therefore, its use at this dose would not be recommended.…”

“…Likewise, the application of Cytolan® at all doses increased the values of FRAP and TEAC to a lesser extent than Cytolan® Stress (Figure 3). Therefore, another additional positive effect of the assayed biostimulants could be the attainment of plants that are more adept at facing oxidative stress (Rodrigues de Queiroz et al 2023). Furthermore, Cytolan® application could deliver plants with enhanced nutritional quality for human consumption; AsA and phenolics being of significant interest in preventing specific diseases (Baslam et al 2013).…”

“…Consequently, the use of phytohormones, nitrogenous compounds, sugars, and polyols serves to diminish the generation of reactive oxygen species (ROS), regenerate oxidized molecules, detoxify ROS, and function as osmoprotectors. Moreover, these compounds positively regulate the expression of genes associated with stress resistance responses (Zulfiqar and Ashraf, 2021; Rodrigues de Queiroz et al 2023). The advantageous effects of these bioactive materials have been observed in plants exposed to stress conditions.…”

“…However, under optimal growth conditions, these effects may not be as conspicuous and, in some cases, negative responses that hinder plant growth have been observed. For example, in several species, the application of compounds such as ascorbate (AsA), proline, melatonin, and tocopherol during normal growth conditions has been shown to inhibit plant growth (Rodrigues de Queiroz et al 2023).…”

Genotype-specific nonphotochemical quenching responses to nitrogen deficit are linked to chlorophyll a to b ratios

“…NPQ kinetics have long been known to change in response to the broadly defined environmental factors (Harvaux and Kloppstech, 2001;Fernández-Marín et al, 2021;Nosalewicz et al, 2022;Rodrigues de Queiroz et al, 2023). More recently the kinetics of NPQ have also been shown to vary as a result of naturally occurring genetic diversity in a range of crop and wild species (Wang et al, 2017;Rungrat et al, 2019;Burgess et al, 2020;Sahay et al, 2023a,b).…”