Comparison of Molecular Mechanisms of Somatic and Zygotic Embryogenesis

Somatic embryogenesis has been used as a model system to understand the mechanisms regulating plant embryogenesis. The morphological and physiological characteristics of somatic embryos are similar to those of zygotic embryos. However, what are the patterns of gene expression during somatic embryogenesis? Here, we review molecular events involved in embryogenesis. Four important transcription factors were isolated from a defective-embryo mutant (LEC1, LEC2, FUS3 and ABI3), and three factors were isolated using deferential screening (SERK, AGL15 and BBM); all are expressed during both somatic and zygotic embryo development. These genes may be important in regulating phytohormone synthesis and phytohormone response during somatic and zygotic embryogenesis. Regulation of embryo-specific LEA gene expression is similar in both somatic and zygotic embryos. Recent research involves examination of new mutants that form embryonic structures.