Proteomics offers insight to the mechanism behind Pisum sativum L. response to pea seed-borne mosaic virus (PSbMV).

Unlabelled: Pea seed-borne mosaic virus (PSbMV) significantly reduces yields in a broad spectra of legumes. The eukaryotic translation initiation factor has been shown to confer resistance to this pathogen, thus implying that translation and proteome dynamics play a role in resistance. This study presents the results of a proteome-wide analysis of Pisum sativum L. response to PSbMV infection. LC-MS profiling of two contrasting pea cultivars, resistant (B99) and susceptible (Raman) to PSbMV infection, detected >2300 proteins, 116 of which responded to PSbMV ten and/or twenty days post-inoculation. These differentially abundant proteins are involved in number of processes that have previously been reported in the plant-pathogen response, including protein and amino acid metabolism, stress signaling, redox homeostasis, carbohydrate metabolism, and lipid metabolism. We complemented our proteome-wide analysis work with targeted analyses of free amino acids and selected small molecules, fatty acid profiling, and enzyme activity assays. Data from these additional experiments support our findings and validate the biological relevance of the observed proteome changes. We found surprising similarities in the resistant and susceptible cultivars, which implies that a seemingly unaffected plant, with no detectable levels of PSbMV, actively suppresses viral replication.

Biological Significance: Plant resistance to PSbMV is connected to translation initiation factors, yet the processes involved are still poorly understood at the proteome level. To the best of our knowledge, this is the first survey of the global proteomic response to PSbMV in plants. The combination of label-free LC-MS profiling and two contrasting cultivars (resistant and susceptible) provided highly sensitive snapshots of protein abundance in response to PSbMV infection. PSbMV is a member of the largest family of plant viruses and our results are in accordance with previously characterized potyvirus-responsive proteomes. Hence, the results of this study can further extend our knowledge about these pathogens. We also show that even though no viral replication is detected in the PSbMV-resistant cultivar B99, it is still significantly affected by PSbMV inoculation.