Potential application of light emitting diodes to improve molecular, physiological, and growth responses in peppermint plant

Abstract

BackgroundClimate change and growing global population are driving forces that shift the agriculture from open fields to environmentally‐controlled confined systems. In such confined systems, plants are adapted to unique light spectra to achieve maximal qualitative and quantitative yields. In the present study, effects of five light spectra on morpho‐physiological and molecular attributes of peppermint were examined. Treatments included a traditional greenhouse considered as the control, a fluorescent light, and four types of light emitting diodes (LED): red, blue, red‐blue (70:30), and white. Leaf samples were collected from plants and analyzed for volatile constituents using a headspace GC–MS. Meanwhile, changes in the expression profile of genes involved in the biosynthesis of menthol were evaluated.ResultsOur results showed that maximal yield (wet and dry biomass) was achieved under greenhouse condition and the red‐blue LED. Application of the red‐blue LED resulted in maximal production of beneficial monoterpenes, which indicate superiority to greenhouse environment. A significant change in the gene expression profile was observed among plants grown under different light treatments. The red‐blue LED was associated with a significant up‐regulation of key genes in the menthol biosynthesis (menthol dehydrogenase and pulegone reductase). This phenomenon was consistent with a higher menthol production under the same condition.ConclusionThe application of red‐blue LED was associated with the highest level of yield and menthol production, whereas it resulted in lower concentrations of unfavorable by‐products (isomenthol, cis‐pulegone, and menthofuran). In conclusion, 70:30 red‐blue LED can be satisfactory applied to maximize growth yield and optimize favorable bioactive constituent in peppermint.