Strong resistance of Arabidopsis thaliana and Raphanus sativus seeds for ionizing radiation as studied by ESR, ENDOR, ESE spectroscopy and germination measurement: Effect of long-lived and super-long-lived radicals

Resistance of seeds for ionizing radiation effects on Arabidopsis thaliana and Raphanus sativus seeds were investigated by ESR, ENDOR, ESE spectroscop y and germination measurement. Two types of free radicals, such as long-liv ed (LL) and super-long-lived (SL) radicals, were produced by the gamma-irra diation in the seeds. More than 90% of the 1 kGy-irradiated-seeds can germi nate probably by decreasing the LL radicals by absorbing water. 10 kGy-irra diated-seeds cannot germinate at all probably due to the existence of signi ficant amounts of the SL radicals even after absorbing water. (C) 1999 Else vier Science Ltd. All rights reserved.