Physically Induced Mutation: Ion Beam Mutagenesis

Ion beams are novel physical mutagens that have been applied to a wide variety of plant species. Unlike other physical mutagens such as X-rays, c-rays, and electrons, ion beams have high linear energy transfer, leading to high double-strand break yields and the resulting strong mutational effects. Takasaki Ion Accelerators for Advanced Radiation Application (TIARA) in Japan was established as the first ion beam irradiation facility for biological use. In this facility, positively charged ions are accelerated at a high speed and used to irradiate living materials, including plant seeds and tissue cultures. By utilizing this approach, several novelmutants have been successfully isolated even from Arabidopsis, in which thousands of mutants have already been obtained using different mutagens. This demonstrates that ion beams are a powerful alternative mutagen with a mutation spectrum different from other chemical, physical, and T-DNA-based mutagens. The application of such an alternativemutagen is of great importance not only to analyze any gene functions through novel mutant isolation, but also to improve global food situations by providing new crop varieties with beneficial traits. In this chapter, we describe the detailed methods of ion beam irradiation anddiscuss its applications in genetic research aswell as plant breeding.