Effects of anoxia on growth and carbohydrate metabolism in suspension cultures of soybean and rice

Abstract

The aim of this work was to compare the carbohydrate metabolism of suspension cultures of soybean ( Glycine max), intolerant of anoxia, with that of cultures of rice ( Oryza sativa), tolerant of anoxia. Soybean cells in anoxia showed no increase in fresh weight, dry weight or extractable protein, and labelled few proteins when supplied with [ 35S]methionine. There were modest (50%) increases in the maximum catalytic activities of sucrose synthase, phosphofructokinase, pyruvate kinase and phosphoenolpyruvate carboxylase. There was a three-fold increase in alcohol dehydrogenase and no detectable change in lactate dehydrogenase and pyrophosphate:fructose 6-phosphate 1-phosphotransferase [PFK(PP i)]. The rates of respiration ( O 2 uptake and CO 2 production in air) and fermentation (CO 2 production in nitrogen), all declined with time in anoxia and the cells died after six days in anoxia. Rice cells in anoxia showed small increases in weight and protein content, and labelled many proteins with [ 35S]methionine. Increased maximum catalytic activities were found for sucrose synthase (× 2), PFK(PP i) (× 6), pyruvate kinase (× 2), alcohol dehydrogenase (× 5) and lactate dehydrogenase (× 2). When rice cells were grown in anoxia, respiration declined steadily. Fermentation increased after four days in anoxia and then declined steadily. However, both respiration and fermentation were still appreciable even after 52 days in anoxia.