DIFFERENTIAL RADIOSENSITIVITY BETWEEN SEEDS AND SEEDLINGS OF NICOTIANA DEBNEYI IN RESPECT OF CHLOROGENIC ACID CONTENT

摘要

Radiosensitivity was compared between seeds and seedlings of Nicotiana debneyi by taking the change in content of a metabolite, chlorogenic acid (CGA), as a marker and it was shown that seeds are more radiosensitive than seedlings. Germination rate of seeds pre-exposed to 100 Gy was 25%, and if they sprouted, the seedlings could never develop normally. Any substances that inhibited the germination were not present or produced in seeds. In seedlings which sprouted from 50 Gy-irradiated seeds, a marked decrease of the growth occurred (similar to 50% of the non-irradiated control). Approximately, a one half diminution of CGA content (amount and concentration) was brought about by 25-Gy irradiation. On the other hand, even 300-Gy irradiation to the 10-day-old seedlings caused no significant retardation of the subsequent growth and almost unaltered the CGA content. The presence of some substance(s) was confirmed, which increased progressively during germination process and could inhibit radiation-induced CGA decrease. Higher radiosensisitivity of Nicotiana debneyi was noted as compared with Nicotiana tabacum. [References: 21]