Signaling Overview of Plant Somatic Embryogenesis

Abstract

Somatic embryogenesis (SE) is a means by which plants can regenerate bipolar structures from a somatic cell. During the process of cell differentiation, the explant responds to endogenous stimuli, which trigger the induction of a signaling response and, consequently, modify the gene program of the cell. SE is probably the most studied plant regeneration model, but to date it is the least understood due to the unclear mechanisms that occur at a cellular level. In this review, the authors seek to emphasize the importance of signaling on plant SE, highlighting the interactions between the different plant growth regulators (PGR), mainly auxins, cytokinins (CKs), ethylene and abscisic acid (ABA), during the induction of SE. The role of signaling is examined from the start of cell differentiation through the early steps on the embryogenic pathway, as well as its relation to a plant’s tolerance of different types of stress. Furthermore, the role of genes encoded to transcription factors (TFs) during the embryogenic process such as the LEAFY COTYLEDON (LEC), WUSCHEL (WUS), BABY BOOM (BBM) and CLAVATA (CLV) genes, Arabinogalactan-proteins (AGPs), APETALA 2 (AP2) and epigenetic factors is discussed.

Transcriptome Analysis Identifies Genes Involved in the Somatic Embryogenesis of Eucalyptus

“…They can be another big category that affect the gene expression during the SE induction [32]. Some TFs have been reported to be associated with the SE, including ABI3, WOX9-1, LEC, WUSCHEL, TALE, BBR-BPC and AP2 [32,42]. In this study we identi ed some dysregulated TF genes speci c in the callus of E. camaldulensis ( Table 2, Additional le 2).…”

“…Méndez-Hernández reviewed the interactions between the different plant growth regulators, mainly auxins, cytokinins, ethylene and abscisic acid (ABA), during the induction of SE [32]. Although the how cells initiate embryo formation is not clear, an irregular distribution of auxins must be established to initiate embryo formation.…”

“…TFs have been reported to function in cell division, cell growth, cell death, cell migration and organization during embryonic development, and respond to biotic and abiotic stresses. They can be another big category that affect the gene expression during the SE induction [32]. Some TFs have been reported to be associated with the SE, including ABI3, WOX9-1, LEC, WUSCHEL, TALE, BBR-BPC and AP2 [32,42].…”

Suspensor-derived somatic embryogenesis in Arabidopsis

“…On the other hand, it is also possible that the process of reprogramming itself involves epigenetic components. Indeed, explants derived from somatic embryos often exhibit an increased frequency of embryogenic cell formation compared to original explants (reviewed in Méndez-Hernández et al, 2019). Whether a link exists between this phenomenon and the recently discovered role of chromatin remodeling in embryogenic cell formation (reviewed in De-la-Peña et al, 2015; Guo et al, 2020) remains to be determined.…”

Transcriptomic profiles of non-embryogenic and embryogenic callus cells in a highly regenerative Upland Cotton line (Gossypium hirsutum L.)

“…A biological stress, such as senescence or an acute stress such as abiotic/biotic factors can trigger stem cell formation through altered chromatin conformation and promiscuous expression of transcription factors [32][33][34]. Transcription factors have been shown to function in an important role on the regulation of plant differentiation [35] and development [36]. In monocots, overexpression of various plant transcription factors such as LEAFY COTYLEDON1 [37], WUSCHEL [38], and BABY BOOM [39] have been shown to improve embryo formation and enhanced regeneration [12].…”