Ⅲ-4. Radiation Chemistry & Biology

RIKEN Accel. Prog. Rep. 51 (2018)

Development of flower color mutations from the light-yellow mutantof spray-mum ‘Southern Chelsea’ by heavy-ion beam re-irradiation
M. Tamari,∗1 G. Watanabe,∗1 F. Tojima,∗1 Y. Hayashi,∗2 and T. Abe∗2Heavy ion beam irradiation induces plant mutation eﬀectively, and is used for plant breeding.1) In
Kagoshima prefecture, we induced ﬂower color mutation on a pink-colored spray-mum cultivar ‘SouthernChelsea’ (Registration number: 17847), using heavyion beam or soft X-ray irradiation. As a result, ayellow ﬂower ‘Southern Chelsea Yellow’ (Registrationnumber: 26523) was developed from the pink-colored
ﬂower color. However, pure white mutants have notbeen obtained from previous mutagenesis experiments.
We also reported that stem segments are more suitable for producing ‘Southern Chelsea’ mutants using
Ar-ion beam irradiation.2) In this report, we describe
the ﬂower color variation that appeared due to the reirradiation of heavy ion beam on the in-vitro cultured
stem of the light-yellow mutant (B25CL-16) obtainedfrom ‘Southern Chelsea.’
Cultured stem segments of ‘B25CL-16’ with an axillary bud were irradiated with Ar-ion beam (LET:280 keV/ µm) or C-ion beam (LET: 23 keV/µm) at
doses from 0.5 to 3 Gy, and each treatment was carried out with 40 stems. After irradiation, the stems ofeach treatment were cultured using in vitro propagation. One month later, the elongated shoots of thesetissues were subcultured with the axillary bud sections
to separate the chimeric mutant sectors, and this wasrepeated twice. The plantlets grown from subcultured
nodes were transferred to a greenhouse to investigate
the ﬂower color mutation in August ﬂowering cultivation.
The numbers of ﬂower-color mutants obtained by
Ar-ion or C-ion beam irradiation were 89 out of 316
and 26 out of 275, respectively (Table 1, Fig. 1). In
the mutation induction of ‘B25CL-16,’ the mutantsin which the yellowish-white of ﬂower petal were observed also included the non-irradiated group. In thecultivated chrysanthemum, the yellow pigment of theﬂower petal is almost carotenoid, and the white ﬂower
color is known to be obtained by the expression ofthe gene encoding carotenoid cleavage dioxygenase 4a(CmCCD4a).3) The yellow color mutants were thought
to be decreased expression of CmCCD4a. The mutantsof yellowish-white colors needs to be investigated withregard to the petal pigment in order to clarify the relationship between the gene and secondary metabolite.
The present study was supported by the Council
for Science, Technology and Innovation (CSTI), Crossministerial Strategic Innovation Promotion Program∗1∗2

Kagoshima Prefectural Institute for Agricultural Development
RIKEN Nishina Center- 242 -Table 1. Flower-color mutation induced by heavy-ion
beam irradiation.
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CFig. 1. ‘B25CL-16’(A) and flower color mutation B: Yellow
C: Yellowish-white steak.

(SIP), “Technologies for creating next-generation agriculture, forestry and ﬁsheries” (funding agency: Biooriented Technology Research Advancement Institution, NARO).
References
1) T. Abe et al., Breed. Res. 16, 67 (2014).
2) M. Tamari et al., RIKEN Accel. Prog. Rep. 50, 274(2017).
3) A. Ohmiya, Agriculture and Horticulture, 82, 11, 1153–1160 (2007).