The first part of the book is devoted to a recapping and integration of the essentials of plant biology, agronomy, and molecular biology so as to be able to address more easily the techniques, concepts, and stakes of plant biotechnology in the various sectors in which it exerts its influence, including agro-food, health, environment, and energy. The second part contains a discussion of the principles and practice of techniques of everything concerning in vitro procedures, identification, and direct and indirect transfer of genes and the control of the functioning of trasgenes. Agronomic, bioindustrial, or environmental applications that are already practised are discussed in the third part of the book. Bioethics, a moral, philosophical, and political discipline, imposed by advances in genetic engineering is treated in the fourth part.