Plant material and temperature treatments
The experiment was conducted using four 11-year-old potted
grapevines of V. vinifera L. cv. Cabernet Sauvignon grafted on
SO4 (Selection Oppenheim No. 4) grown in a phytotron. Vines
were trained on a Guyot trellising system and each vine carried
4–10 clusters of grapes. The experiment started approximately
1 week before veraison, when berry softening started, and continued
to fruit maturity. The two temperature regimes consisted of a high
day (06.00–20.00 h) temperature (max. 35 C) and a control (max.
25 C). Under both conditions, the night-time (20.00–06.00 h)
temperature was 20 C. The photoperiod corresponded to natural
day length. Twenty-five per cent of the berries (15–20 berries) ineach cluster was sampled at random from each temperature
treatment at 2 week intervals after veraison, and the berries were
pooled to produce two samples for each vine. Each sample pool was
derived from the different clusters. The berries were manually
peeled with a scalpel to eliminate any flesh. The berry skin was
frozen immediately in liquid nitrogen and stored at –80 C until use