Applications to biotechnology; Ion-beam breeding of plants

バイオ技術への応用; イオンビーム植物育種

田中 淳; 長谷 純宏

Tanaka, Atsushi; Hase, Yoshihiro

The characteristics of ion beams on the mutation induction in higher plants were investigated. Mutation induction rates by using known visible Arabidopsis mutant phenotypes indicated that mutation frequencies induced by carbon ions were 20-fold higher than those induced by electrons. Molecular analyses showed that half of the mutants induced by ion beams possessed large DNA alterations such as intergenic deletion, inversion and translocation, while the rest had point-like intragenic mutations. On the other hand, mutants induced by low LET radiation such as electrons predominantly possessed point-like intragenic mutations. It is possible that ion beams induce a limited number of large and irreparable DNA lesions, resulting in the production of null mutations that show a new mutant phenotype. Novel mutants, such as those that are UV-B resistant, have serrated petals and sepals, or lack anthocyanins, have been induced by 220 MeV carbon ions in Arabidopsis. In chrysanthemum and carnation, several kinds of flower-color and flower-form mutants that have never been produced by -rays or X-rays were induced by carbon ions. These observations indicate that the characteristics of mutations induced by ion beams are high frequency and broad spectrum, and produce novel mutants. Many breeding programmes are using mutants induced by ion beams and successfully producing useful new crop varieties.