The Role of Carnosic Acid in the UV‐B Stress Resistance Signalling Pathway in Arabidopsis thaliana

ABSTRACT Carnosic acid (CA) is recognized as an antioxidant that confers protection to plants against various forms of oxidative stress, including UV‐B stress. However, limited research has been conducted to elucidate the molecular mechanisms underlying its defence against UV‐B stress. In this study, we demonstrated that CA exhibits more efficacy compared to other antioxidants in UV‐B resistance. Moreover, CA was found to enhance the accumulation of secondary metabolites in Arabidopsis leaves. Through the analysis of differentially expressed genes in response to UV‐B stress with or without CA treatment, we uncovered that the exogenous application of CA effectively activates the flavonoid biosynthesis pathway in Arabidopsis to improve resistance of Arabidopsis to UV‐B stress.