Proteome Analysis of Nicotiana tabacum Cells following Isonitrosoacetophenone Treatment Reveals Defence-Related Responses Associated with Priming

Abstract

Proteins play an essential regulatory role in the innate immune response of host plants following elicitation by either biotic or abiotic stresses. Isonitrosoacetophenone (INAP), an unusual oxime-containing stress metabolite, has been investigated as a chemical inducer of plant defence responses. Both transcriptomic and metabolomic studies of various INAP-treated plant systems have provided substantial insight into this compound’s defence-inducing and priming capabilities. To complement previous ‘omics’ work in this regard, a proteomic approach of time-dependent responses to INAP was followed. As such, Nicotiana tabacum (N. tabacum) cell suspensions were induced with INAP and changes monitored over a 24-h period. Protein isolation and proteome analysis at 0, 8, 16 and 24 h post-treatment were performed using two-dimensional electrophoresis followed by the gel-free eight-plex isobaric tags for relative and absolute quantitation (iTRAQ) based on liquid chromatography and mass spectrometry. Of the identified differentially abundant proteins, 125 were determined to be significant and further investigated. INAP treatment elicited changes to the proteome that affected proteins from a wide range of functional categories: defence, biosynthesis, transport, DNA and transcription, metabolism and energy, translation and signalling and response regulation. The possible roles of the differentially synthesised proteins in these functional classes are discussed. Results indicate up-regulated defence-related activity within the investigated time period, further highlighting a role for proteomic changes in priming as induced by INAP treatment.

Metabolomic Reconfiguration in Primed Barley (Hordeum vulgare) Plants in Response to Pyrenophora teres f. teres Infection

“…Changes affecting organic acids (e.g., through reversible transaminase reactions) and amino acids might affect nitrogen and carbon metabolism and link the associated metabolic cycles in support of anaplerotic reactions to replenish the citric acid cycle if it becomes depleted of intermediates in response to biosynthetic demands. Furthermore, alterations in carboxylic acid levels were reported in plants during stress responses, and it was suggested that the tricarboxylates could modulate signal transduction cascades linked to plant defence responses [ 50 , 51 ]. In this context, citrate and fumarate were reported as inducers of defence priming in Arabidopsis thaliana through complex signalling pathways [ 51 ].…”

“…Furthermore, alterations in carboxylic acid levels were reported in plants during stress responses, and it was suggested that the tricarboxylates could modulate signal transduction cascades linked to plant defence responses [ 50 , 51 ]. In this context, citrate and fumarate were reported as inducers of defence priming in Arabidopsis thaliana through complex signalling pathways [ 51 ].…”