Studies in the respiratory and carbohydrate metabolism of plant tissues. XII. Further studies of the formation of CO 2 and the changes in lactate, alcohol, sucrose, pyruvate and α -ketoglutarate in potato tubers in nitrogen and in air following anaerobic conditions

Abstract

A specific chromatographic method was used to show that, in air following anaerobiosis, lactate was oxidized to pyruvate and that the latter might be metabolized in the tricarboxylic acid cycle. Our earlier view (Barker & Mapson 1953 b )was thus confirmed. As was expected, both the form and mechanism of the outburst of CO 2 in air after nitrogen were simpler with fully sweet potatoes at 1 °C than with low-sugar potatoes at 10 °C. In the former the outburst of CO 2 appeared to be due only to consumption of lactate; in the latter the outburst of CO 2 was attributed in part to consumption of lactate and in part to change in sugar content. With certain stocks of fully sweet potatoes at 1 °C, the pyruvate oxidase system appeared to be saturated with substrate initially in air after nitrogen; moreover, after 22 days in nitrogen, the pyruvate oxidase system appeared to be almost, if not completely, inhibited. A general, but not a close, correlation was observed between the rates of aerobic respiration and of increase of lactate and output of CO 2 in nitrogen, the rates of these functions being affected by differences in sugar content (Barker 1933) and in metabolic state.