Stomatal Development and Impact of Stomatal Movement on Secondary Metabolism in Medicinal Plants - Abstract
Stomata are minute microscopic pores found in the epidermis of the aerial parts of plants and reported to be present about 400 million years ago in the earth eco-system. They serve as a gate way of gaseous exchange in plant on which the whole world depends to get oxygen to breathe. In this review efforts have been made to discuss process of stomatal development and its control by a genetic tool box comprising of many genes and signalling cascades. There is discussion on interlinking of genes to formation of stomata in strict control of relevant genes. Identity of cells, asymmetric cell division, stomatal density, patterning and clustering are discussed with respect to signals coming from environment and or the hormonal cascade. Fate of absorbed light energy in green plants is briefed and stomatal opening and closing mechanism under initial and mild stress conditions which shifts primary metabolism to the secondary metabolism resulting in increased secondary metabolites production is highlighted. Impact of disrupted membrane integrity and permanent damage to photosystem II on growth in plants under prolonged and severe stress conditions is elaborated. In nature, plants have different pheno-phase, life span, preferred growth season, soil type and climatic requirements. Duration and intensity of stress at different phenol-phase may have different impacts on secondary and primary metabolism. Focusing particularly on medicinal plants, we explained how difficult is to define a hypothetically optimum stress condition which cause increase in secondary metabolites without significantly compromising the potential biological yield. Studies on crop specific responses to stress of various intensities and duration imposed at different pheno-phases are required to be conducted that may further help in explaining the optimum stress conditions in medicinal plants.