Figure 11.

Localization of acidic α-glucosidase activity in the apoplastic fraction of mustard seedlings. A, Time course of elution of α-glucosidase activity from intact mustard seedlings. Three-day-old mustard seedlings grown under water were shaken in extraction buffer containing 1 m NaCl for 6 h. α-Glucosidase in the medium was assayed periodically with 4-MUG at pH 4.5. B, Activity of α-glucosidase (Aglu) at either pH 4.5 or 7.0 and malate dehydrogenase (MDH) in the elution buffer from A after 6 h, and in extracts from similar but untreated plants. Data represent the means ± sd (n = 3). U, Unit.