Dose response curves after irradiation of Arabidopsis seeds: a possible explanation for the “saturation” in mutant frequency at high radiation doses

Abstract

Mutant frequency “saturation” in Arabidopsis' “main” inflorescence after fast neutron or X-ray treatment of seeds was observed using cell populations with heterogeneous radiation-sensitivities. Mutant frequencies were determined in (1) morphologically normal and conspicuous plants, (2) main and lateral inflorescences, and (3) different M 1-fertility classes. At moderate radiation doses (47 Gy fast neutrons and 233 Gy X-rays) significant differences in mutant frequencies between different M 1-fertility classes were observed. This suggests that cell populations with heterogeneous sensitivities were studied. No significant differences were observed either between the mutant frequencies in main and lateral inflorescences or between the ones in inflorescences of morphologically normal and conspicuous plants. This suggests that these inflorescences were formed by cell populations with similar but heterogeneous sensitivities.