Priming of protein expression in the defence response of Zantedeschia aethiopica to Pectobacterium carotovorum.

The defence response of Zantedeschia aethiopica, a natural rhizomatous host of the soft rot bacterium Pectobacterium carotovorum, was studied following the activation of common induced resistance pathways­systemic acquired resistance and induced systemic resistance. Proteomic tools were used, together with in vitro quantification and in situ localization of selected oxidizing enzymes. In total, 527 proteins were analysed by label-free mass spectrometry (MS) and annotated against the National Center for Biotechnology Information (NCBI) nonredundant (nr) protein database of rice (Oryza sativa). Of these, the fore most differentially expressed group comprised 215 proteins that were primed following application of methyl jasmonate (MJ) and subsequent infection with the pathogen. Sixty-five proteins were down-regulated following MJ treatments. The application of benzothiadiazole (BTH) increased the expression of 23 proteins; however, subsequent infection with the pathogen repressed their expression and did not induce priming. The sorting of primed proteins by Gene Ontology protein function category revealed that the primed proteins included nucleic acid-binding proteins, cofactor-binding proteins, ion-binding proteins, transferases, hydrolases and oxidoreductases. In line with the highlighted involvement of oxidoreductases in the defence response, we determined their activities, priming pattern and localization in planta. Increased activities were confined to the area surrounding the pathogen penetration site, associating these enzymes with the induced systemic resistance afforded by the jasmonic acid signalling pathway. The results presented here demonstrate the concerted priming of protein expression following MJ treatment, making it a prominent part of the defence response of Z. aethiopica to P. carotovorum.