Cryptogein, a fungal elicitor, remodels the phenylpropanoid metabolism of tobacco cell suspension cultures in a calcium‐dependent manner

Abstract

Plant cells use calcium-based signalling pathways to transduce biotic and/or abiotic stimuli into adaptive responses. However, little is known about the coupling between calcium signalling, transcriptional regulation and the downstream biochemical processes. To understand these relationships better, we challenged tobacco BY-2 cells with cryptogein and evaluated how calcium transients (monitored through the calcium sensor aequorin) impact (1) transcript levels of phenylpropanoid genes (assessed by RT-qPCR); and (2) derived-phenolic compounds (analysed by mass spectrometry). Most genes of the phenylpropanoid pathway were up-regulated by cryptogein and cell wall-bound phenolic compounds accumulated (mainly 5-hydroxyferulic acid). The accumulation of both transcripts and phenolics was calcium-dependent. The transcriptional regulation of phenylpropanoid genes was correlated in a non-linear manner with stimulus intensity and with components of the cryptogein-induced calcium signature. In addition, calmodulin inhibitors increased the sensitivity of cells to low concentrations of cryptogein. These results led us to propose a model of coupling between the cryptogein signal, calcium signalling and the transcriptional response, exerting control of transcription through the coordinated action of two decoding modules exerting opposite effects.

Metabolic shift from withasteroid formation to phenylpropanoid accumulation in cryptogein-cotransformed hairy roots of Withania somnifera (L.) Dunal

“…Upliftment of ferulic acid accumulation was also reported in tobacco cell lines challenged with cryptogein protein (Amelot et al 2011). To accumulate such quantity of ferulic acid, it was suggested that a reverse monolignol pathway was operative in cryptogein-elicited tobacco (Amelot et al 2011).…”

“…Enzyme activities are expressed in nanokat (nkat) mg −1 protein. Each value is the mean±SD from at least three independent experiments (Amelot et al 2011). These findings with tobacco cell lines encouraged us to examine the contents of soluble and cell wall-bound phenolics in both cryptogein-cotransformed and normal hairy root lines.…”

“…Cryptogein binds to the plasma membrane and initiates rapid Ca 2+ influx and activates protein kinases and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) for reactive oxygen species (ROS) production and nitric oxide synthesis (Lecourieux et al 2000). Tobacco cells challenged with cryptogein showed upregulation of phenylpropanoid genes leading to enhanced accumulation of cell wall-bound phenolic compounds (Amelot et al 2011).…”

Tobacco plantlets ameliorate oxidative stress upon expression of a cryptogein gene

“…Cryptogein application in tobacco BY-cell suspension culture showed increased transcript accumulation of most genes for phenylpropanoid pathway enzymes including PAL, 4CL and CAD (Amelot et al 2011). Enhanced accumulation of PAL transcript was observed in cryptogein-cotransformed hairy root cultures of Withania somnifera where cryptogein was also endogenously expressed (Sil et al 2015).…”

A Proteomic Approach to Evaluate the Effects of Endogenous Expression of Cryptogein Gene in Crypt-Transgenic Plants of Bacopa monnieri

“…The cryptogein initiates a signal transduction possibly by binding cryptogein to an N-glycosylated plasma membrane receptor protein [10,11], followed by the activation of several protein kinases, such as the wound-induced protein kinase (WIPK), the salicylic acid-induced protein kinase (SIPK) [12,13]. Calcium influxes triggered by these kinases subsequently give rise to calcium-dependant transcriptional changes [14] and activate a wide array of cellular responses, including an NADPH oxidase-dependent oxidative burst [15,16]. Upregulation of several chitinases, peroxidases, peptidyl-prolyl isomerases and proteinase inhibitors in intercellular fluid of cryptogein-treated tobacco leaves were observed using a proteomic approach [17].…”