Impact of Light Stress on Plant Based Medicinally Active Compounds

Abstract

Light has several positive and negative impacts on plant growth and physiological processes. Medicinal plants contribute significantly higher proportions of world plant flora and are natural source of rich medicinal compounds. Sufficient literature is available on plant responses to light stress but studies on medicinal plants are limited. This review discusses how different light conditions affect production of plant-based medicinal compounds which are broadly secondary products formed during adverse environmental conditions to cope up the stress. Here, some medicinal plants are reviewed which were exposed to different light conditions including blue light, red light, yellow light, green light, far red light, wavelength specific light treatments, pulsed pre light, specific light intensity, light shade treatments, and supplemental ultraviolet-B radiation. Secondary metabolites considered for the review are anthocyanin, flavonoids, alkaloids, essential oils, cannabinoids and glucosinolates. Most of the results revealed increase in content of medicinal compounds under differentially exposed light conditions with maximum effect under sUV-B exposure. Advancement in the knowledge of medicinal plants response to light stress can help in understanding the mechanism of medicinal compound formation and their regulation which can be further utilized in the production of medicinally active compounds.