Phosphorylation landscape on time-resolved SYR1-dependent systemin signaling pathway

Systemin was identified in 1991 as the first plant signaling peptide, and is required for defense against insect herbivores and necrotrophic pathogens in tomato plants. Systemin was first conceived as a hormone-like, long-distance messenger mediating the activation of systemic defense responses far from the site of insect attack. It was later shown to rather act as a phytocytokine, amplifying the local wound response for production of downstream signals resulting in defense gene activation in distal tissues. Systemin perception and signaling rely on the systemin receptor SYR1. However, SYR1-dependent signaling, and how systemin signaling differs from other peptide-mediated signaling pathways, is largely unknown. Here we used a Solanum peruvianum suspension cell culture to analyze phospho-proteomic responses triggered by 10 nM systemin. Samples were analyzed in a time series of 0, 1, 2, 5, 15, and 45 min after systemin treatment. To identify systemin-specific events a mutant cell culture lacking the SYR1 systemin receptor was analyzed in parallel. The experiment was performed in six biological replicates. Samples numbering scheme: Genotype_TreatmentTimeReplicate(e.g.,WT_S53 corresponding to wild-type cells treated with systemin, for 5min, the 3rd biological replicates)