Fig. 1-4 Trichomes: left, wild type with trichome; right, trichomeless (glabra) mutant induced by C ions irradiation.

Fig. 1-5 Seed color: Pigment deposition in immature seed coat 4 days after fertilization: upper wild type; lower C ion-induced mutant.

Plants have continued relations with various radiation including cosmic rays since they appeared on the Earth. Nowadays improvement of plants is carried out using artificial radiation. A recent example is the improvement of the Japanese pear called "Nijusseiki", which is susceptible to disease. Radiation Breeding National Institute of Agrobiological Resources MAFF developed a mutation of the Japanese pear using gamma ray from Co-60. This mutation called "Gold Nijusseiki" is resistant to black spot disease. JAERI has studied the radiation-induced mutation of "Arabidopsis thaliana" by irradiating its seed using ion beams of He, C, Ne, Ar, etc. of various energies from TIARA (Takasaki Ion Accelerators for Advanced Radiation Application). "Arabidopsis thaliana" was selected for biological investigation, because it has the following characteristics: 1) the plant size is small and self-and cross-pollination is possible 2) the generation time is short (4-6 weeks) 3) the genome size is small, 4) the gene bank has been established 5) plant regeneration is possible from the protoplasm. It has been observed that irradiation of the seed by C ions produces the trichomeless mutant as shown in Fig.1-4 and the mutant which accumulates reddish brown pigment (anthocyanin) scattered in the seed coat cells as shown in Fig.1-5. JAERI has carried out R&D of a new cell surgery process by means of local irradiation technique using heavy-ion micro beams and of fusion (unsymmetrical cell fusion) of locally irradiated cells. This technology is expected to give new valuable scientific information on the improvement of plants in future.

Reference S. Tano, Arabidopsis thaliana and ion beams, Genshiryoku-kogyo, 41(3), 24, (1995).

Select a topic in left column