LET dependence of lethality of carbon ion irradiation to single tobacco cells.
OBJECTIVE
To determine the radiation sensitivity and relationship between linear energy transfer (LET) and relative biological effectiveness (RBE) in single plant cells irradiated with heavy ions.


METHODS
Single cells were isolated from the tobacco BY-2 cell line and irradiated with carbon ions (78.6-309 keV microm(-1)) and gamma-rays (0.2 keV microm(-1)). Two weeks after irradiation, colonies with 16 cells or more derived from the irradiated cells were counted as survivors. The surviving fraction was fitted using the single-hit, multitarget theory.


RESULTS
The doses needed to reduce the surviving fraction of the cells to 0.1 (D10) of gamma-rays and carbon ions were 47.2 and 10.5-12.6 Gy, respectively. The RBE based on the D10 peaked at an LET of 247 keV microm(-1). The inactivation cross-section of carbon ions reached a plateau of 11.3 microm2 at an LET of 247 keV microm(-1).


CONCLUSIONS
The radiation sensitivity of single tobacco cells was much lower than that of mammalian cells, although the mean number of base pairs per chromosome in the two cell types was similar. The RBE peak based on the D10 of carbon ions in single tobacco cells occurred at a higher LET than it does in other organisms.
Yokota
Y
Y
Laboratory of Plant Breeding Science, Graduate School of Agriculture, Kyoto Prefectural University, Hangi-machi 1-5, Shimogamo, Sakyo-ku, Kyoto 606-8522 Japan.
Hase
Y
Y
Shikazono
N
N
Tanaka
A
A
Inoue
M
M
D002244:Carbon / Q000009:adverse effects*; D005720:Gamma Rays; D020450:Heavy Ions / Q000009:adverse effects*; D018499:Linear Energy Transfer; D011836:Radiation Tolerance; D012062:Relative Biological Effectiveness; D014026:Nicotiana / Q000166:cytology / Q000528:radiation effects*
D002244:Carbon