Fig. 4. VlbZIP30-overexpressing grapevine plants grown under glasshouse conditions show enhanced drought tolerance.

a Drought tolerance phenotypes of Thompson Seedless (WT) and transgenic lines (#14, #36, and #46). Eight-month-old plants (upper panel) were dehydrated for 40 days (lower panel). Bar, 5 cm. Chlorophyll content (b) and leaf RWC (c) of WT and transgenic lines. Leaves were detached from WT and transgenic lines after both control and drought treatments. RWC relative water content. Changes in photosynthetic parameters of transgenic grapevines relative to the WT during a drought period, including transpiration rate (d), stomatal conductance (e), and intercellular CO₂ concentration (f). Measurements were made on sunny days between 10:00 and 12:00 a.m. In all cases, the values are means ± SEs (n = 3). Asterisks indicate statistical significance (*0.01 < P < 0.05, **P < 0.01, Student’s t test) between the WT and transgenic lines