Adventitious Organogenesis

Abstract In plants, differentiated somatic cells may dedifferentiate and subsequently redifferentiate into (adventitious) shoots, roots, or embryos. The formation of adventitious shoots (caulogenesis) and roots (rhizogenesis) is specified with the term adventitious organogenesis, whereas somatic embryogenesis refers to the formation of adventitious (somatic) embryos. Adventitious organogenesis occurs frequently during natural life but may be achieved at very high frequencies in tissue culture. It is one of the basic tools in vegetative plant propagation and plant breeding. In propagation, adventitious formation of shoots is important in micropropagation of many crops and adventitious formation of roots from (micro)cuttings is required to obtain complete plants from excised shoots. In breeding, adventitious organogenesis is essential among others in transformation and haploid production. This article reviews adventitious organogenesis from the point of view of developmental biology and deals with physiological, biochemical, molecular, and genetic aspects. It covers both practical and fundamental aspects.