Regulation of starch and sugar levels in tobacco leaves by gibberellic acid

Abstract

Gibberellic acid (GA 3 ) significantly reduced the level of starch in green leaves of tobacco plants. The total α-amylase activity and the specific activities of α-amylase and invertase were increased by GA 3 treatment. Hydrolysis of starch during flue-curing contributed greatly to the increased level of reducing sugars in cured leaf tissue; decreasing the level of starch in green leaves by GA 3 effectively lowered the level of reducing sugars after curing.