In Vitro Transformation of Root meristem to Shoot and Plantlets in Vanilla planifolia

Abstract

A study is reported of histogenesis and organogenesis during the processes leading up to plantlet formation in tip cultures of aerial roots of Vanilla planifolia. Young root tips excised from aerial roots, less than 15 cm long, when cultured in liquid MS medium containing IAA and KN showed gravitropic response until cap lysis began. With the collapse of the distal half of the cap, the cells of the quiescent centre divided forming a hemispherical mass of cells. Further localized divisions on the periphery of the hemisphere resulted in a number of meristemoids each of which differentiated into a shoot meristem with leaf primordia. Procambium differentiated first beneath the apical meristem after two to three leaf primordia had formed and then at the base of the leaves. After a few leaves have been formed a root meristem differentiated in close lateral proximity to the basal end of the shoot procambium. Formation of a plate of vasculature at the nodal region of the first formed leaf, procambialization of the root and the bridging up of the shoot and root vasculature with the nodal plate are described.