Biological effects of three types of ionizing radiation on creeping bentgrass.

Purpose: Gamma-rays and carbon ions are frequently used for mutation breeding in diverse plant species, whereas proton ions have been rarely used for this purpose. This study assessed the potential of proton ions for plant mutation breeding. Materials and methods: We compared the effects of radiation on creeping bentgrass seeds with γ-rays, proton ions, and carbon ions on seed germination, plant growth parameters, and DNA fragmentation. Results and conclusions: The lethal dose 50 (LD50) doses based on seed germinability were 115.9 Gy (γ-rays), 225.1 Gy (proton ions), and 57.7 Gy (carbon ions). Threshold doses for survival were 150 Gy (γ-rays), 150 Gy (proton ions), and 25 Gy (carbon ions). Suppression of plant growth was displayed at 100 Gy (γ-rays), 25 Gy (proton ions), and 25 Gy (carbon ions). Similar patterns of decreasing head DNA percentage were observed for γ-rays and proton ions. Carbon ions induced the lowest frequency of DNA fragmentation. The biological effects of the ionizing radiation types on creeping bentgrass are summarizable as follows: germination, carbon ions (C)>γ-rays (G)>proton ions (P); survival, C > P = G; growth, C ≥ P > G; DNA fragmentation, G ≥ P > C. These results indicate that proton ions are useful as a physical mutagen in plant mutation breeding.