Host: The Japan Radiation Research Society
Accelerated ion beam is an excellent mutagen in plant breeding which can induce higher mutation frequencies and wider mutation spectrum than those of low linear energy transfer (LET) irradiations, such as X-rays, gamma-rays and electrons (Okamura et al. 2003, Yamaguchi et al. 2003). Mutation breeding operation of two Saintpaulia ionahta cultivars using the method combining plant tissue culture technique and carbon ion beam irradiations were set out at Institute of Modern Physics from 2005 (Zhou et al. 2006). As a result, a chlorophyll-deficient (CD) mutant of Mauve cultivar, which could transmit the character of chlorophyll deficiency to its progeny through three continuous tissue culture cycles, was obtained (Zhou et al. 2006). This year, we gained another mutant of Indikon cultivar from those samples irradiated by 80MeV/u 12C6+ provided by Heavy Ion Facility in Lanzhou (HIFRL) at the dose of 25 Gy in 2005, whose flower-color has changed from violet to light pink, simultaneously, among the petals the androecia and gynoecium have disappeared. Two of the five sepals have mutated to malformed petals and the number of petals also varied from eleven to fourteen. Moreover, the edge of leaves has become smooth while the normal type is jagged and the color of the abaxial side of leaf also varied from aubergine to light green. On the other side, we could not obtain any regenerated adventitious shoots from the leaf explants of this mutant using the normal Saintpaulia ionahta tissue culture methods unless the recipes of callus or shoot inducing medium was adjusted to appropriate proportion. It is particularly because the entogenous plant hormone level or the hormone receptor in this mutant have changed. In addition, DNA sequence analysis of such ion beam induced mutations and the measuring of entogenous hormone level or receptor should also be executed in the near future to analyse and identify the genetic alterations of these regenerated plantlets at the molecular level.
