Chapter 5 - Plant tissue culture: Somatic embryogenesis and organogenesis

Abstract

The term “totipotency,” first coined by Gottlieb Haberlandt in 1902, is now very well known by everyone in the field of plant tissue culture. The plant tissue culture technique is now being routinely used for micropropagation, conservation, and transformation all over the world. Plant cells are plastic as they can be differentiated, dedifferentiated, and re-differentiated a number of times. Both somatic and reproductive cells of the plant have this developmental plasticity. Utilizing the totipotency and plasticity features of the plant cell, two fundamental pathways of propagation/regeneration exist, viz., somatic embryogenesis and organogenesis in plant tissue culture. Somatic embryogenesis is a process in which an embryo is derived from a single somatic cell which is regenerated as a whole plant later. Somatic embryos are believed to have bipolar structure having both apical and basal meristems which can form shoot and root, respectively. On the other hand, organogenesis is defined as the development of organs such as shoot, root, flowers, and tubers from an explant material. Although these fundamental pathways of plant regeneration have been reported many times already, a detailed understanding of their subtypes, affecting factors, advantages, limitations, and applications in crop improvement is lacking. To cover the basic information and recent findings on somatic embryogenesis and organogenesis, this chapter was written.