Early leaf removal around the cluster zone is a common technique applied in viticulture with the aim to regulate yield components and improve fruit quality. Despite the increasing amount of information on leaf removal and its impact on total soluble solids, anthocyanins, and polyphenols, much less is known regarding aroma compounds. In order to verify the hypothesis that defoliation, applied before or after flowering, could impact the biosynthesis of thiol precursors, we performed an experiment on Sauvignon blanc. We provided evidence that differential accumulation of thiol precursors in berries is affected by the timing of defoliation, and this impact was related to modifications in the biosynthetic pathway. Furthermore, the possible interaction between leaf removal treatment and seasonal weather conditions, and its effect on the biosynthesis of volatile precursors are discussed. Our results suggested that in Sauvignon blanc the relative proportion of 4-S-glutathionyl-4-methylpentan-2-one (G-4MSP) and 3-S-glutathionylhexan-1-ol (G-3SH) precursors can be affected by defoliation, and this could be related to the induction of two specific genes encoding glutathione-S-transferases (VvGST3 and VvGST5), while no significant effects on basic fruit chemical parameters and methoxypyrazines were ascertained under our experimental conditions.
COBISS.SI-ID: 4892155