Radiosensitivity of a triploid clone of Tradescantia determined in its stamen hairs

Abstract

Somatic mutations from blue to pink were induced by 60 Co gamma rays in the stamen hairs of KU 9 clone (3x) at a rate of 1.64 × 10 −3 pink mutant events per hair per R or 2.32 × 10 −4 pink mutant cells per hair cell per R. A D 0 value of 171 R was determined for the terminal meristematic cells of the stamen hairs. This D 0 value was compared with ten other D 0 values obtained earlier from seven different 2x, 4x or 12x clones, and it was reconfirmed that higher radioresistance of higher polyploids is best explained by their smaller chromosome volumes rather than by genetic redundancy. The effects of dose rate on somatic mutation rate and loss of reproductive integrity were also clearly demonstrated. Pink mutant cells were found to have a lower reproductive ability on the average than non-mutant cells.