Signaling Overview of Plant Somatic Embryogenesis.

Hugo A Méndez-Hernández,Clelia De-La-Peña,Víctor M Loyola-Vargas,Randy N Avilez-Montalvo,Johny Avilez-Montalvo,Analesa Skeete,Yary L Juárez-Gómez,Maharshi Ledezma-Rodríguez

doi:10.3389/fpls.2019.00077

Hugo A Méndez-Hernández, Clelia De-La-Peña + Show 6 more

Open Access

https://doi.org/10.3389/fpls.2019.00077

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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.

Highlights

Higher plant embryogenesis is divided conceptually into two distinct phases: early morphogenetic processes that give rise to embryonic cell types, tissues, and organ systems, and late maturation events that allow the fully developed embryo to enter a desiccated and metabolically quiescent state (West and Harada, 1993; Goldberg et al, 1994)
In seedlings that over-expressed SOMATIC EMBRYOGENESIS RECEPTORLIKE KINASE1 (SERK1), the mRNA exhibited a 300–400% increase in the efficiency of the initiation of Somatic embryogenesis (SE). These results suggest that an increase in the expression levels of SERK1 confers embryogenic competence to cells in culture (Hecht et al, 2001)
Since the 1950s, the research on the SE process has gone from empirical approaches to a more methodical investigation leading to the production of somatic embryos (Loyola-Vargas, 2016)

Summary

INTRODUCTION

Higher plant embryogenesis is divided conceptually into two distinct phases: early morphogenetic processes that give rise to embryonic cell types, tissues, and organ systems, and late maturation events that allow the fully developed embryo to enter a desiccated and metabolically quiescent state (West and Harada, 1993; Goldberg et al, 1994). The use of exogenous auxins, either alone or in combination with other PGRs or stress, induces the expression of different genes, which modify the genetic program of the somatic cells and regulate the transition to each of the stages during the development of SE (Loyola-Vargas and Ochoa-Alejo, 2016). In response to a higher level of expression of SERK, the number of embryogenic calluses increase as well as the formation of somatic embryos (Nolan et al, 2003) Another important participant in the regulation of SE and plant embryo development is the LEC family of TFs (Guo et al, 2013). The other factor actively involved during the SE induction, process, and development is epigenetic (Us-Camas et al, 2014; De-la-Peña et al, 2015; Duarte-Aké and De-la-Peña, 2016)

14-3-3 Adaptor Proteins

Findings

CONCLUDING REMARKS