The metabolism of aged seeds. The involvement of the pentose phosphate pathway in respiration in germinating rye grains of various ages

Winter rye grains from different harvest years (having distinctly different viabilities) were studied in terms of germination, total dehydrogenase activity and growth analysis. Reduction of seed vigor and viability was accompanied by a decrease in the intensity of embryo respiration during germination. The use of (1-14C) glucose and (6-14C) glucose showed that germinating rye embryos catabolize glucose through glycolysis, Krebs cycle and the pentose phosphate pathway. It was also shown that the C6/C1 ratio in respiring embryos initially increased during the first 48 hours of germination, then dropped, which suggests a mounting contribution of the PP pathway to the overall cotabolism. The oxidation of glucose in, embryos from the most deteriorated grains proceeded through glycolysis and Krebs cycle only.