Changes in Some ATP-Dependent Activities in Seeds during Treatment with Polyethyleneglycol and during the Redrying Process

Abstract

During the imbibition of seeds in polyethyleneglycol (PEG), increasing amounts of ATP accumulated up to 24 h. Similar amounts accumulated in the seeds during 4–5 h of imbibition in water. Radioactive amino acids were increasingly incorporated in the acid-insoluble fraction up to 24 h imbibition in PEG, as well as in water, after which a sharp decrease occurred up to 5 d of imbibition. If seeds were imbibed in PEG or water in the presence of radioactive acetate, water-insoluble radioactivity increased linearly in seeds during 5 d of imbibition. The amounts of incorporated amino acids or acetate were about double in PEG-imbibed as compared with in water-imbibed seed. The incorporation of AMP into the acid-insoluble fraction in seeds imbibed in PEG in the presence of radioactive AMP levelled off after 24 h followed by a sharp decrease of up to 10% of the peak 5 d after the start of imbibition. In water-imbibed seeds the incorporation of AMP continued to increase during at least 5 d of imbibition. During redrying of PEG-treated seeds (24 h), at least 80% of the accumulated ATP decreased during 18 d. The total radioactive amino acids and nucleotide decreased during 3 d of redrying by 20% and 60%, respectively. At that time, the acid-insoluble incorporates increased by 20% and 50%, respectively. Some of the AMP was released as CO2.