Direct Somatic Embryogenesis

Abstract

Direct somatic embryogenesis is the formation of somatic embryos or embryo-genic tissue directly from the explant without the formation of an intermediate callus phase (Raghavan 1986). In embryogenesis systems, this is almost always what happens (Merkle et al. 1990; Finer 1994). The production of a callus usually is undesirable if embryogenesis is the goal of the research. Two known exceptions to direct embryogenesis are carrot (see Chap. 7) and alfalfa, where a mass of cells that is relatively unorganized can form embryos after the proper manipulations. Carrot and alfalfa have become regular and useful systems for embryogenesis studies due to the relative ease of producing plants in vitro. Unfortunately, in most other plants somatic embryogenesis is more difficult to obtain, but good progress is being made (Attree and Fowke 1993).