Abstract
Changes in the amount of ATP in Pinus thunbergii seeds during the course of
germination showed the triphasic pattern to be similar to those in water uptake and respiration; (1) a rapid increase within 12 hours after the start of imbibition, (2) plateau phase until radicle emergence, and (3) subsequently a sharp increase. However, in the seed imbibed in the dark or at low temperature (4°C), the third phase did not occur. When the dark-imbibed seed was exposed to light, the amount of ATP increased immediately and then changed as in the normal course of germination. This increase seems to occur preceding protein synthesis. On the contrary, the irradiation by the far-red light, which inhibits the initiation of protein synthesis, did not bring about this increase of ATP. Therefore, ATP production systems are preserved in dry seeds and reactivated immediately after absorption of water in either light- or dark-imbibed seeds. However, in the dark-imbibed seeds this reactivating system does not seem to operate unless new metabolic phases are induced by the light.
