Genetic and epigenetic modes of the regulation of somatic embryogenesis: a review

Somatic embryogenesis (SE) is a mode of stimulated plant cell totipotency wherein embryos form without fertilization either through somatic or vegetative origins. SE has two main phases: induction and a developmental phase. The induction phase comprises cell proliferation and dedifferentiation, whereas the developmental phase involves the differentiation of somatic embryos under appropriate stimuli. As such, SE is categorized into two main types: direct (without an intervening callus) and indirect (includes a callus phase). This review presents the influence of various major factors such as explants, abiotic stresses, and the concentrations and variations of plant growth regulators on SE. In addition, genetic components such as miRNA, transcription factors, and epigenetic events (DNA methylation and chromatin remodeling) that are potentially implicated in SE are described briefly. Furthermore, SE applications and SE-related abnormalities are also discussed in detail.