The grapevine (Vitis vinifera L.) is one of the oldest and most economically significant fruit crops in the world. The grapevine’s ability to adjust the expression pattern of specific genes in response to stress causes alterations in its cellular proteome, with metabolic and physiological consequences, resulting in efficient adaptation to environmental stresses. Proteomic studies are crucial to understand the mechanisms by which plants adapt to adverse conditions, identifying stress-response proteins and elucidating their specific role in metabolic pathways.
In this study, the two-dimensional electrophoresis (2-DE) technique was applied to evaluate the protein profile of V. vinifera cv. ‘Touriga Nacional’ grown in field conditions under two water availability settings (irrigated and non-irrigated vines). Grapevine leaves were collected and homogenized with liquid nitrogen. Total proteins were extracted following a methanol/chloroform precipitation protocol and then separated by 2-DE.
The analysis of the resulting proteomic profiles uncovered differences in protein expression. Out of 47 protein spots considered for analysis, 10 were identified as differentially expressed: 9 spots showed significantly higher expression in non-irrigated vines, while 1 spot showed a significantly higher expression in vines under irrigation.
By comparing the apparent molecular weight of the differentially expressed spots with published data, it was possible to find potential correspondences with proteins previously identified in other studies of drought stress in grapevines, including proteins related to defense responses against stress, such as heat shock proteins or antioxidant enzymes, proteins related to carbohydrate and energy metabolism, such as ATP synthase CF1 beta subunit or glyceraldehyde-3-phosphate dehydrogenase, and photosynthesis‑related proteins, such as RuBisCO large subunit or LHC chlorophyll-binding proteins. The involvement of these proteins in grapevine’s adaptation to drought are validated by including other Portuguese traditional cultivars with different plasticities under this environmental constraint. Differentially expressed protein spots common among genotypes are further identified by LC-MS/MS.
