Role of Pyrophosphate : D-Fructose 6-Phosphate 1-Phosphotransferase during Germination of Rice Seeds

Abstract

The pyrophosphate : D-fructose 6-phosphate 1-phosphotransferase (PPi-PFK) and 6-phosphofructokinase (ATP-PFK) activities were measured during germination of rice seeds. In plumule and radicle, the PPi-PFK activity was the highest just at the appearance of these organs. On the other hand, the activity of ATP-PFK was almost constant, and was always lower than that of PPi-PFK. Furthermore, the PPi-PFK activity of the apex including a growing point of plumule and of radicle was much higher than that of each base. On the contrary, the ATP-PFK activity did not show any significant difference between the apex and base, and was about equal to the PPi-PFK activity detected in the base of these organs. When these enzyme activities were measured in embryo, the highest activity of PPi-PFK was detected just before the onset of decrease of the seed weight. However, the activity of ATP-PFK did not show any significant change, and was always lower than that of PPi-PFK.