Influence of red- and blue-dominant light spectra on the biosynthesis of mono- and sesquiterpenes in mint (Mentha × piperita) essential oil

Mentha has great economic importance in the food and pharmaceutical industries. As climate conditions become increasingly unstable, the cultivation of herbs in greenhouses is gaining importance. Light-Emitting Diodes enable to manipulate light spectra to biochemically engineer the synthesis of secondary plant metabolites. Peppermint (Mentha × piperita) was grown under a blue- (400-500 nm) or red- (600-700 nm) light-dominated spectrum to investigate the influence of spectral adaptation on the biosynthesis of valuable essential oil compounds. The full spectrum served as a control. Whereas the essential oil yield, composition, and minor secondary metabolite content remained unaffected by light treatment, light-dependent variations in the major mint terpenes were detected by gas chromatography-mass spectrometry analysis. Under the red-dominated spectrum, the relative contents of the potential hepatotoxic compounds pulegone and menthofuran were reduced by ≤30 % and 10 %, respectively. Furthermore, those of the economically valuable compounds menthone and menthol were increased by 58 % and 45 %, respectively.