Grapevine (Vitis vinifera) is an economically important fruit crop that is subject to many types of insect and pathogen attack. To better elucidate the plant response to Lobesia botrana pathogen
infection, we initiated a global comparative proteomic study monitoring steady-state
protein expression as well as changes in N-glycosylation, phosphorylation, and Lys-acetylation in control and infected mesocarp and exocarp from V. vinifera cv Italia. A multi-parallel, large-scale proteomic approach employing iTRAQ labeling prior to three
peptide enrichment techniques followed by tandem mass spectrometry led to the identification of a total of 3059
proteins, 1135 phosphorylation sites, 323 N-linked glycosylation sites and 138 Lys-acetylation sites. Of these, we could identify changes in abundance of 899
proteins. The occupancy of 110 phosphorylation sites, 10 N-glycosylation sites and 20 Lys-acetylation sites differentially changed during L. botrana
infection. Sequence consensus analysis for phosphorylation sites showed eight significant motifs, two of which containing up-regulated
phosphopeptides (X-G-S-X and S-X-X-D) and two containing down-regulated
phosphopeptides (R-X-X-S and S-D-X-E) in response to pathogen
infection. Topographical distribution of phosphorylation sites within primary sequences reveal preferential phosphorylation at both the N- and C termini, and a clear preference for C-terminal phosphorylation in response to pathogen
infection suggesting induction of region-specific
kinase(s). Lys-acetylation analysis confirmed the consensus X-K-Y-X motif previously detected in mammals and revealed the importance of this modification in plant defense. The importance of N-linked protein glycosylation in plant response to biotic stimulus was evident by an up-regulated
glycopeptide belonging to the
disease resistance response
protein 206. This study represents a substantial step toward the understanding of
protein and PTMs-mediated plant-pathogen interaction shedding light on the mechanisms underlying the grape
infection.