ABSTRACT
The development of amylase activity in extracts from de-embryonated and GA(3)-treated de-embryonated maize kernels (Zea mays L.) was determined during a 10-day incubation period. The increase in activity was compared with activity extracted from endosperms dissected from germinating whole kernels. Chromatographic analysis of reaction products as well as physicochemical characterization demonstrated that the activities from GA(3)-treated and nontreated tissue were comparable and that part of the activity was attributable to alpha-amylase.Concomitant with the increase in activity was the appearance of a number of starch-degrading bands, as evidenced by polyacrylamide gel electrophoresis. Actinomycin-D (20 mug/ml) and cycloheximide (5 mug/ml), when present in the incubation medium at early periods of incubation, were capable of inhibiting the development of amylase activity and of preventing the appearance of the starch-degrading bands.The results indicate that the development of alpha-amylase activity in de-embryonated maize kernels is independent of an embryo or an exogenous source of gibberellic acid and suggest that this process involved protein synthesis.
ABSTRACT
The responses of common purslane (Portulaca oleracea L.) plants to 2-methoxy-3,6-dichlorobenzoic acid (dicamba) were found to be similar in many respects to ethylene fumigation effects. Dicamba and ethylene increased the permeability of cell membranes in purslane tissues. An increased efflux of electrolytes was observed in the bending region of the stems of dicamba-treated plants. Epinastic leaves after dicamba (10 micrograms) and ethylene (microliter per liter) treatments showed an increased efflux of rubidium. The permeability effects were observable within 1 day after dicamba or ethylene application. Protein metabolism in purslane leaves was not influenced by dicamba until 2 days after treatment, as indicated by reduced nitrate reductase activity. Inhibition of phenylalanine-U-(14)C incorporation into protein was observed 3 days after treatment. Ethylene reduced both phenylalanine-U-(14)C incorporation into protein and nitrate reductase activity within 1 day. Dicamba caused a rapid increase in ethylene production in purslane plants to levels many times greater than those observed in untreated plants. It was concluded that the dicamba-enhanced production of ethylene is responsible for many of the observed effects of the herbicide.
