Chemical Regulation of Callus Growth, Organogenesis, Plant Regeneration, and Somatic Embryogenesis inAntirrhinum majusTissue and Cell Cultures

Abstract

Excised stem explants of Antirrhinum majus L. var. 'Kymosy blanc' were grown in a defined medium to investigate factors influencing bud and root development, callus induction, and somatic embryogenesis. Auxins such as indoleacetic acid (IAA) and naphthaleneacetic acid (NAA) caused limited callus development and abundant root formation, whereas 2,4-dichloro phenoxyacetic acid (2,4-D) promoted soft friable callus with embryos and occasional develop ment of thick abnormal roots. 2-Naphthoxy acetic acid (NOA) and coconut milk (CM) used together induced friable green callus growth and differentiation of small globular embryos which eventually developed into plantlets after transfer to auxin-free agar mineral medium containing sucrose. Cytokinins such as benzyladenine (BA), zeatin, and kinetin induced compact green callus but in the absence of auxin failed to promote organogenesis. The inter action of IAA and kinetin resulted in the regeneration of the whole plant from stem explants. When NAA was used with kinetin, shoot development was totally inhibited and abundant roots were formed. Thus, the alternative morphogenetic events probably reflect the bio chemical subtleties occurring within the callus as a result of differences of actual endogenous levels of growth substances in the tissues studied. These experiments have been performed and interpreted on a histological basis.