CYP81D11, an apocarotenoid-responsive cytochrome P450, enhances photosynthesis and stress tolerance in plants

β-Cyclocitric acid and its precursor β-cyclocitral are signaling apocarotenoids that trigger defense and detoxification mechanisms, enhancing plant tolerance to abiotic stresses. From a transcriptomic analysis of Arabidopsis (Arabidopsis thaliana) plants exposed to each apocarotenoid over several exposure times, we identified a gene (CYP81D11) encoding a cytochrome P450 that is strongly induced under all conditions and is under the control of the TGAII-SCL14 transcription regulator. Overexpressing the CYP81D11 gene in Arabidopsis led to a high tolerance to high light and water stresses, while a CYP81D11-deficient mutant was sensitive to both stress conditions. CYP81D11 expression levels were inversely correlated with the accumulation of reactive carbonylated lipid-oxidation products in leaves. The transcriptomic profile of the CYP81D11 overexpressor revealed a selective upregulation of genes related to photosynthesis and response to high light stress. High expression levels of CYP81D11 enhanced photosynthetic electron transport, CO2 fixation, and biomass production. These effects occurred in high light, not in low light, and were associated with a noticeable decrease in singlet oxygen photoproduction. These findings indicate that CYP81D11 is a key component in the regulation of plant stress tolerance, enhancing the photosynthetic capacity of leaves and preventing accumulation of reactive carbonyls. This gene could be a target for improving photosynthesis in high-light environments.