Organogenesis

Organogenesis is the alternative plant regeneration pathway, in which morphological changes in callus tissue lead directly to the formation of shoots and roots, rather than to an embryo-like structure. Shoot formation from callus is specifically termed caulogenesis, while root formation is termed rhizogenesis; a fully regenerated plantlet needs both to occur, whether simultaneously or, more commonly, in sequence (shoots first, roots induced afterward). Organogenesis is induced in vitro by introducing plant growth regulators into the MS medium, and the choice of regulator determines which organ forms: auxins and cytokinins are the two classes of hormone specifically responsible for inducing shoot and root formation. Because organogenesis and somatic embryogenesis both start from the same callus tissue and are both governed largely by …