Transcription Factors in the Regulation of Somatic Embryogenesis

Abstract

Somatic embryogenesis (SE), the process through which already differentiated cells reverse their developmental programme and become embryogenic, requires drastic changes in the transcriptome of the explant cells. Among the various factors that underlie this developmental switch, genes encoding transcription factors (TFs), which constitute the sequence-specific DNA-binding proteins, are widely accepted as playing a central function in the gene expression regulation. In recent years, intensive analysis of the global transcriptomes of plant cells that are undergoing embryogenic transition and the use of Arabidopsis (a model in plant genomics) in studies on the genetic control of SE have substantially contributed to the identification of SE regulators. A survey of SE-associated transcriptomes illustrated the combinational effects of stress and hormone signalling that are related to the in vitro environment that is imposed during a culture. Accordingly, among the TFs that are considered to be essential in SE induction, those that are involved in stress and hormone plant responses and especially flower development were found to be most frequent. This chapter provides a comprehensive review of the current knowledge about the TFs that are involved in the induction of SE in plant explants that are cultured in vitro. In addition to a general characterisation of the TF transcriptomes that are associated with SE induction in different plants, the individual TF genes with documented functions in the regulation of SE are presented with a special reference to their possible targets and the TF-controlled molecular mechanisms that underlie SE induction.

Current Perspectives on the Auxin-Mediated Genetic Network that Controls the Induction of Somatic Embryogenesis in Plants

“…The transcripts of the TF genes that are related to hormone responses, in particular those that control auxin metabolism and signalling are overrepresented in the SE-transcriptomes of many plants (reviewed in [119]). In Arabidopsis, over 40% of the SE-modulated TF genes have been annotated to hormone-related pathways, primarily to the auxin metabolism and signalling pathways [76].…”

Azacitidine (5-AzaC)-treatment and mutations in DNA methylase genes affect embryogenic response and expression of the genes that are involved in somatic embryogenesis in Arabidopsis

“…Recently, significant progress has been made in identifying genes and revealing their biological functions in the genetic mechanisms that control the embryogenic transition in somatic cells using the SE culture of Arabidopsis (reviewed in Nowak and Gaj 2016). In contrast, our understanding of the epigenetic processes that contribute to the regulation of SE remains very limited.…”

Molecular and epigenetic regulations and functions of the LAFL transcriptional regulators that control seed development

“…and lec2 mutants have lower ability to undergo somatic embryogenesis (Lotan et al, 1998;Stone et al, 2001;Gaj et al, 2005;Santos Mendoza et al, 2005;Suzuki et al, 2007;Stone et al, 2008;Gao et al, 2009;Feeney et al, 2013;Guo et al, 2013;Jia et al, 2013;Wojcikowska et al, 2013;Jia et al, 2014;Zhang et al, 2014b;Ikeuchi et al, 2015;Nowak and Gaj, 2016;Horstman et al, 2017;Magnani et al, 2017;Mozgova et al, 2017;Wójcik et al, 2017;Lee and Seo, 2018). This LEC1/LEC2 activity probably explains why the induction of the LAFL genes is accurately controlled during seed development and expression strongly repressed during vegetative growth.…”