Cucumber mosaic virus resistance: Comparative proteomics of contrasting Cucumis sativus cultivars after long-term infection.

Plant viruses are a significant threat to a wide range of host species, causing substantial losses in agriculture. Particularly, Cucumber mosaic virus (CMV) evokes severe symptoms, thus dramatically limiting yield. Activation of plant defense reactions is associated with changes in the cellular proteome to ensure virus resistance. Herein, we studied two cultivars of cucumber (Cucumis sativus) resistant host Heliana and susceptible host Vanda. Plant cotyledons were mechanically inoculated with CMV isolate PK1, and systemic leaves were harvested at 33 days post-inoculation. Proteome was profiled by ultrahigh-performance liquid chromatography and comprehensively quantified by ion mobility enhanced mass spectrometry. From 1516 reproducibly quantified proteins using a label-free approach, 133 were differentially abundant among cultivars or treatments by strict statistic and effect size criteria. Pigments and hydrogen peroxide measurements corroborated proteomic findings. Comparison of both cultivars in the uninfected state highlighted more abundant photosynthetic and development-related proteins in resistant cucumber cultivar. Long-term CMV infection caused worse preservation of energy processes and less robust translation in the susceptible cultivar. Contrary, compatible plants had numerous more abundant stress and defense-related proteins. We proposed promising targets for functional validation in transgenic lines: A step toward durable virus resistance in cucurbits and other crops. SIGNIFICANCE: Sustainable production of crops requires an understanding of natural mechanisms of resistance/susceptibility to ubiquitous viral infections. We report original findings of comparative analysis of plant genotypes exposed to CMV. Deep discovery proteomics of resistant and susceptible cucumber cultivars, inoculated with widespread phytovirus, allowed to suggest several novel molecular targets for functional testing in plant protection strategies.