CRISPR-Cas9 Approaches to Enhance Contents of Plant Secondary Metabolites

Abstract

Plant secondary metabolites are the byproducts of primary metabolite biosynthesis. Their absence is non-critical for plant survival, as they are not involved in basic life functions. The classes of plant secondary metabolites include terpenes, phenolics, N-containing and S-containing compounds. Often, they render crop plants unsuitable for insect herbivory. Colour, flavour and taste of edible parts of the plant and their nutritional quality are greatly influenced by the plant secondary metabolites. They also play a significant role in human health and nutrition. Genetic engineering is used to desirably modify secondary metabolite production in plants. CRISPR (clustered regularly interspaced short palindromic repeats), a revolutionary genome editing technology, equipped with precision and the ease of manipulation. It is mostly used for imparting resistance in plants to biotic and abiotic stresses, and for enhancing their nutritional quality and yield. For instance, CRISPR technology has been successfully used to enhance β-Carotene content in soybean, cassava, tomato and in rice to alleviate vitamin A deficiency in humans. CRISPR can also be used to down regulate production of human toxic secondary metabolites in crop plants like tobacco. In this chapter, an earnest effort has been made to introduce, classify and describe role and significance of plant secondary metabolites. A brief review on progress made so far in the application of transgenic and RNAi technologies is also provided. CRISPR technology, its types and application for plant secondary metabolites has been elaborated. Considering the recent trends, scope and prospectus of CRISPR technology, it has immense potential for application in plant secondary metabolite research.