Formation of amylase in disks of bean hypocotyl.

Amylase activity has been studied in disks of hypocotyl of Phaseolus vulgaris L. Although some activity is present in untreated hypocotyls, it is greatly increased when disks are incubated 4 days in water containing kinetin (5 mg/liter). Gibberellic acid and 2,4-dichlorophenoxyacetic acid do not increase this activity appreciably. The increased activity can be shown by subsequently incubating the disks on starch agar plates and testing these with iodine-potassium iodide solution, or by using the original incubation medium and extracts of the disks in reactions with soluble starch. A variety of tests favor the assumption that the enzyme is alpha-amylase and that it is synthesized during the incubation period.