2.11 Gus staining
Tobacco seedlings harboring the ProNtMYB12a : Gus vector were transformed to MS medium containing 0, 50, 88 (Control), 150, and 200 mM sucrose for 7 days. Gus staining was performed with a GUS Staining Kit (Coolaber, SL7160) following the manufacturer’s instructions. The seedlings were immersed in the staining buffer provided by the kit under vacuum infiltration for 30 min, and then kept at 37°C overnight. The green seedlings were decolorized with 95% and 75% ethanol successively. The photographs were taken using an OLYMPUS SZ 61 stereomicroscope.