2003 Volume 17 Issue 4 Pages 298-301
An ion microbeam system for irradiating single plant cells was developed to analyze exact biological effects of ion beams. Tobacco BY-2 protoplasts were used as a model of single plant cells. Protoplasts were cultured in thin agarose medium on a specially designed irradiation-vessel, which has a CR-39 nuclear track detector (a 100-µm thick sheet). The colony formation rate of unirradiated protoplasts was 22.7 ± 6.7% (mean ± SE of 3 different experiments) after a month of culture. Protoplasts were irradiated with programmed numbers of 18.3 MeV⁄u carbon ions that had been collimated by a 20-µmφ micro-aperture. After the irradiation, the positions within the protoplasts that were hit with ions were accurately determined by etching the CR-39 sheet in 13.4M KOH solution at 27 °C for 9h. The hit rate of the carbon ion microbeam, i.e., the percent of the ion particles that hit the protoplast that they were aimed at, was 56.9 ± 2.4% (mean ± SE of 7 different replications).
