TRANSCRIPTIONAL REMODELING IN LEAVES AND BERRIES OF VITIS VINIFERA L. CV. SAUVIGNON BLANC GRAPEVINES SUBJECED TO PARTIAL-DOUBLE PRUNING

Canopy management in vineyard is a key operation affecting both shoot and fruit development. Recently, partial double-pruning has been proposed to delay bunch rot epidemics in European vineyards. We investigated how partial double-pruning (DC) influenced gene expression in leaves and berries of Vitis vinifera L. cv. Sauvignon Blanc grapevines as compared to a traditional single cane-pruning (SC). In 2024, trascriptomics and GO gene ontology analysis were applied on leaf and berry samples collected at two developmental stages (leaves: BBCH 69 and BBCH 73; berries: BBCH 73 and BBCH 79). [FP1] Data are supported by a four-year assessment of grapevine responses encompassing vegetative growth, yield components, and fruit composition. Results point out organ-specific and stage-dependent transcriptional changes in response to DC that are mostly evident during developmental phases characterized by active growth and structural reorganization. The strongest changes occurred at BBCH 73[FP2] , including the upregulation of genes related to cell wall modification and response to stress categories. Genes involved in transcription factors and secondary metabolism functional classes were consistently downregulated early on, suggesting a temporary shift in resource allocation. In contrast, leaves collected at BBCH 69 and berries collected at BBCH 79 showed few changes between SC and DC. Integrating molecular data with agronomical assessment revealed that partial double-pruning is effective to significantly reduce vegetative vigor as compared to SC with less than proportional yield losses [FP3] and almost unvaried fruit composition at harvest. The transcriptomic responses, such as cell wall remodeling in leaves, heat and oxidative stress responses in berries at BBCH 73, and downregulation of secondary metabolism, reflect these physiological adjustments associated with temporary changes in microclimate and canopy structure. Overall, grapevines can react to changes in canopy structure by activating specific molecular pathways rather than broader stress responses. From a practical point of view, this translates in the relevance of partial double-pruning to manage grapevine vigor either for too vigorous vineyards or for plots characterized by strong intra-field variability requiring site-specific actions belonging to precision viticulture strategies.