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

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.