This edited book highlights the plant and cell/organ culture systems, and environmental and genetic transformation-based modulation of biochemical pathways. Special focus is given to microRNA-based technology, heterologous systems expression of enzymes and pathways leading to products of interest, as well as applications using both model and non-model plant species.Metabolic engineering is usually defined as the re-routing of one or more enzymatic reactions to generate new compounds, increase the production of existing compounds, or facilitate the degradation of compounds. Plants are the foundation of numerous compounds which are synthesized via assimilated complex biosynthetic routes. Plants have evolved an incredible arrangement of metabolic pathways leading to molecules/compounds capable of responding promptly and effectively to stress situations imposed by biotic and abiotic factors, some of which supply the ever-growing needs of humankind for natural chemicals, such as pharmaceuticals, nutraceuticals, agrochemicals, food and chemical additives, biofuels, and biomass. However, in foreseeable future we will be forced to think about the accessibility of resources for the generations to come. For these reasons, the book proposes alternative options of food/food supplement, medicines and other essential items, by using plant metabolic engineering approach. This book is of interest to teachers, researchers and academic experts. Also, the book serves as additional reading material for undergraduate and graduate students of biotechnology and molecular biology of plants.