Genetic and Molecular Control of Somatic Embryogenesis

Abstract

Somatic embryogenesis is a method of asexual reproduction that can occur naturally in various plant species and is widely used for clonal propagation, transformation and regeneration of different crops. Somatic embryogenesis shares some developmental and physiological similarities with zygotic embryogenesis as it involves common actors of hormonal, transcriptional, developmental and epigenetic controls. Here, we provide an overview of the main signaling pathways involved in the induction and regulation of somatic embryogenesis with a focus on the master regulators of seed development, LEAFY COTYLEDON 1 and 2, ABSCISIC ACID INSENSITIVE 3 and FUSCA 3 transcription factors whose precise role during both zygotic and somatic embryogenesis remains to be fully elucidated.

Keywords: LAFL; embryogenesis; epigenetic control; transcriptional regulation.

Figure 1

The roles of LAFL genes in somatic embryogenesis (SE) and zygotic embryogenesis (ZE). IAA: auxins, CKs: cytokinins, GA: gibberellins.

Figure 2

The possible roles of LEC2 in somatic embryogenesis. (A): LEC2 can have a dual function, one specific to embryogenesis, the other inducing maturation genes. The embryogenesis function may lead to SE or ZE depending on the type of cell it is expressed in, as well as possible stress and epigenetic modifications. (B): LEC2 induces stress through the accumulation of reserve specific compounds in the cells.

Figure 3

General overview of genes involved in somatic embryogenesis or zygotic embryogenesis in interaction with LEC1, ABI3, FUS3, and LEC2 (LAFL) transcription factors. Hormone-related genes are represented in brown, epigenetic regulators in red, transcription factors in black and pioneer factors in bright pink.