“…Gamma-ray irradiation has advantages over treatment with chemical mutagens such as ethyl methane sulfonate (EMS) in that it induces DNA damage relatively randomly, resulting in various types of mutations including point mutations, indels, and chromosome aberrations (Tanaka et al, 2010). Therefore, gamma-ray irradiation has been the main treatment used in various plants, particularly ornamental plants such as orchids (Kikuchi, 2000), Anthurium (Puchooa, 2005), chrysanthemum (Kumar et al, 2012;Yamaguchi et al, 2008), and Paphiopedilum (Luan et al, 2012), for over 80 years. Recently, irradiation with ion beams, which are different from gamma-ray in that they are generated by accelerators and has specific mass and charge according to types of ions, has been proven to be very effective in mutation breeding in terms of biological effectiveness, mutation frequency, and range of mutation spectrum compared with gamma ray (Hase et al, 2012).…”