Characterization of the third SERK gene in pineapple (Ananas comosus) and analysis of its expression and autophosphorylation activity in vitro

Abstract

Two somatic embryogenesis receptor-like kinase genes (identified as AcSERK1 and AcSERK2) have previously been characterized from pineapple (Ananas comosus). In this work, we describe the characterization of a third gene (AcSERK3) in this family. AcSERK3 had all the characteristic domains and shared extensive sequence homology with other plant SERKs. AcSERK3 expression was studied by in situ hybridization and quantitative real-time PCR to analyze its function. Intense in situ hybridization signals were observed only in single competent cells and competent cell clusters; no hybridization signal was detected in the subsequent stages of somatic embryogenesis. AcSERK3 was highly expressed in embryogenic callus compared to other organs, e.g., 20–80 fold more than in anther but similar to that of non-embryogenic callus, which was 20–50 fold that of anther. AcSERK3 expression in root was 80 fold higher than in anther and the highest amongst all organs tested. These results indicate that AcSERK3 plays an important role in callus proliferation and root development. His-tagged AcSERK3 protein was successfully expressed and the luminescence of His6-AcSERK3 protein was only ∼5% of that of inactivated AcSERK3 protein and reaction buffer without protein, and 11.3% of that of an extract of host Escherichia coli pET-30a. This finding confirmed that the AcSERK3 fusion protein had autophosphorylation activity.

Histological analysis of somatic embryogenesis in pineapple: AcSERK1 and its expression validation under stress conditions

“…We have confirmed the in vitro phosphorylation activity of prokaryotic expressed His6-AcSERK3 in our previous study (Ma et al 2014). In addition, the in vitro phosphorylation activity of prokaryotic expressed His6-AcSERK1 protein was detected by the decrease of the luminescence of ATP.…”

In silico and in vivo analysis of ABI3 and VAL2 genes during somatic embryogenesis of Coffea arabica: competence acquisition and developmental marker genes

“…The CaABI3 gene exhibited high expression in the initial embryo formation (globular stage), which inferred that gene played key roles during the coffee embryogenesis initiation. Similar pattern was observed in SERK expression -molecular marker of competent cells-in Passiflora edulis (Rocha et al 2016), Ananas comosus (Ma et al 2014) and Cyclamen persicum (Savona et al 2012). Therefore, we suggest that ABI3 gene may be also used to identify cell competency for SE process in C. arabica.…”

Cellular and molecular changes associated with competence acquisition during passion fruit somatic embryogenesis: ultrastructural characterization and analysis of SERK gene expression

“…Throughout this process, SERK expression is not restricted to one particular cell type but occurs in morphologically distinct single cells and small cell clusters. This expression continues through proembryogenic mass formation until the embryos are at the globular stage (Schmidt et al 1997;Ma et al 2012;Ma et al 2014). Furthermore, somatic embryos of different species arise from morphologically distinct cell types that express SERK genes.…”

“…Furthermore, somatic embryos of different species arise from morphologically distinct cell types that express SERK genes. For example, enlarged and vacuolated cells that are derived from the procambium and express SERK were embryogenically competent in carrot (Schmidt et al 1997), but in pineapple, the proliferating embryogeniccompetent cells were small, isodiametric, non-vacuolated and cytoplasm rich and expressed AcSERK2 and AcSERK3 (Ma et al 2012;Ma et al 2014).…”