A cytochrome P450 involved in apocarotenoid signaling enhances plant photosynthetic capacity and photooxidative stress tolerance

{beta}-cyclocitric acid and its precursor {beta}-cyclocitral are signaling apocarotenoids which trigger defense and detoxification mechanisms enhancing plant tolerance to abiotic stresses. From a transcriptomic analysis of Arabidopsis 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 very tolerant phenotype to high light stress while a CYP81D11- deficient mutant was photosensitive. The transcriptomic profile of the CYP81D11 overexpressor revealed a selective upregulation of genes related to photosynthesis and the response to high light stress. Photosynthetic electron transport, CO2 fixation and biomass production were noticeably improved by high expression levels of CYP81D11. These effects occurred in high light, not in low light, and were associated with a noticeable reduction of singlet oxygen photoproduction. These findings indicate that CYP81D11 is a key component of {beta}-cyclocitral-induced stress tolerance, acting through enhancement of the photosynthetic capacity of leaves. This gene could be a new target for improving photosynthesis, particularly in sunny environments.