Role of Plant Somatic Embryogenesis Receptor Kinases (SERKs) in Cell-to-Embryo Transitional Activity: Key at Novel Assorted Structural Subunits

Abstract

Somatic Embryogenesis Receptor Kinase (SERK) family of receptor kinases is functionally diverse, involved in cell-to-embryo transition and controlling a number of other fundamental aspects of plant development. The morphological transformation of somatic to embryonic cells has drawn scientific attention utmost due to remarkable genetic-switch system evolved across species. Receptor kinases having direct role in somatic embryogenesis (SE) and involved in other functions are designated as "SERK" and "SERK-like" genes, respectively. We aim for phylogenetic reconstruction to reveal major SERK groups across plant species (angiosperm to gymnosperm) for their functional diversification. Data indicate that the development of SERK proteins occurred prior to the divergence of monocots and eudicots. Also, the SERK orthology is not directly proportional to their functions. Structure prediction results identified novel transmembrane topologies, short linear motifs and O-glycosylation sites exclusively in SERK proteins than SERK-like proteins. Comparative temporal expression analyses of SERK and SERK-like genes provided significant accordance with their physiological function. The identification of intrinsic disordered regions (IDRs) exclusively in SERK proteins was assumed to perceive external stress-induced signals that may lead to rapid protein folding. In a result it switches-on the precise cellular signals essential for the acquisition of SE. Moreover, the regulatory sequences of SERK genes are evolved with unique cellular fate deciding AP2-like ethylene responsive transcription factor AINTEGUMENTA binding sites for their spatial expression in SE. Based on these analyses we suggest future avenues of research that may be imperative for elucidating the importance of SERK gene evolution in SE.

Signaling Overview of Plant Somatic Embryogenesis

“…This gene is expressed in cells that develop in somatic embryos until the globular stage (Schmidt et al, 1997), just before the transition from the differentiation state to the development state. The expression of SERK increases several times in the embryogenic cells of A. thaliana (Hecht et al, 2001), Citrus unshiu (Shimada et al, 2005), Dactylis glomerata (Somleva et al, 2000), G. hirsutum (Pandey and Chaudhary, 2014), Helianthus annuus (Thomas et al, 2004), Medicago truncatula (Nolan et al, 2003), Solanum tuberosum (Sharma et al, 2008), Vitis vinifera (Maillot et al, 2009), Cocos nucifera (Pérez-Núñez et al, 2009), Oryza sativa (Hu et al, 2005; Ito et al, 2005), Theobroma cacao (de Oliveira Santos et al, 2005), Triticum aestivum (Singh and Khurana, 2017), Zea mays (Baudino et al, 2001), Cyrtochilum loxense (Cueva et al, 2012), and A. angustifolia (Steiner et al, 2012).…”

Application of Developmental Regulators for Enhancing Plant Regeneration and Genetic Transformation

“…Some other transcription factor genes have also been found to promote embryogenesis, such as SERK, WIND1, and LBD [152,153] (Table 5). The somatic embryogenesis receptorlike kinase (SERK) protein, a receptor kinase involved in the regulation of somatic embryo development, was first identified in carrot cells [154].…”