Metabolism of barley seed during early hours of germination.
The growth process in germinating barley seeds and its inhibition by actinomycin D and puromycin were investigated. Soon after seeds are imbided, their respiratory activity increases several fold, and the protein- and carbohydrate-synthesizing systems become active. The immediate activation of protein synthesis and its inhibition by actinomycin D and puromycin suggest that the dry seed has all the components necessary for protein synthesis.Although a good correlation exists between the rate of oxygen uptake and that of protein synthesis during the first 12 hr of germination, respiration appears to be independent of protein synthesis during the first 8 hr, as reflected by the insensitivity of the respiratory process to actinomycin D and puromycin. However, after 8 hr both antibiotics reduce oxygen uptake as well as subsequent seedling growth.The distribution of (14)C, derived from labeled glucose during the early hours of barley germination, among various fractions of metabolites, indicated that 50 to 70% of the utilized glucose appeared in (14)CO(2). The rest of the incorporated label appeared in hemicelluloses and starch, water-soluble ethanol-insoluble carbohydrates, and to a lesser extent in proteins and cellulose.
Abdul-Baki
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Market Quality Research Division, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland 20705.