Shoot organogenesis from petunia leaves
Petunia is among the most popular bedding plants and is mainly propagated by seeds. Petunia is a member of the Solanaceae family. Within this family, petunia is particularly responsive to tissue culture techniques and can be regenerated from anthers, protoplasts, seedling tips, stems, leaves, and other tissues and organs. Petunia is an ideal plant for a tissue culture laboratory exercise because it is responsive in vitro; seeds are easy to obtain, store, and germinate; seedlings are easy to grow; and it can be scheduled year-round. This chapter uses the leaves for the initial explant and examines the effects of cytokinin and auxin on the regeneration of shoots and roots and the formation of callus. It demonstrates both direct and indirect shoot organogenesis. Direct shoot organogenesis occurs when shoots form directly from the original explant without an intervening callus. In contrast, indirect shoot organogenesis happens when callus first forms from the explant, then shoots arise from the callus tissue.