Analysis of Genes for Stigma Coloration in Rice - IRRI books

Mutagenic effects of
accelerated argon ion irradiation
in rice
M.T. Mei, Q.F. Zuo, Y.G. Lu, H. Deng, and T.C. Yang
Since research work with accelerated heavy ions has shown that high-linear energy
transfer (LET) ion radiation can induce certain types of mutation more effectively than
low-LET radiation in mammalian cells (Cox et al 1977), yeast, and maize (Mei et al 1987,
Yang 1979), we initiated this study in 1987 to explore the potential use of heavy ion
radiation in rice mutation breeding. Dry seeds of Bianpizhan, an indica variety, were
irradiated with various doses of an 40 Ar ion beam (E=400 MeV/u; LET = 117 keV/µm)
generated by the BEVALAC accelerator at Lawrence Berkeley Laboratory. The field
experiment was implemented at the South China Agricultural University. Injurious
effects on the M1 were observed. The dose-seedling survival curve as well as the dosefertility
curve (Fig. 1) showed that D 50-s and D 50-f were about 93.7 Gy and 67.0 Gy,
respectively.
By using the plant-to-row method, more than 7,000 M 2 plants were investigated, and
mutants with variations in quantitative or morphological characters were sought.
Doses from 60 to 120 Gy were effective in inducing mutation in dry seeds, and the
mutation frequency was rather high, especially for mutations involving semidwarfism,
earliness, and grain shape (Table 1). Also, more than one mutated character was
frequently found in a single plant. Thus, accelerated heavy ion radiation might be useful
in rice mutation breeding. Further studies comparing the mutation effectiveness of
various heavy ion and gamma ray treatments are being conducted at the South China
Agricultural University.
Seedlings of 43 stable mutants in the M 5 and the original variety were tested for
allozymic differences in 10 isozymes—SDH, EST, ICD, PGI, GOP, POX, ACP, AMP,
PGD, and ME, which represent 17 loci—by starch gel electrophoresis (Second 1982,
Wu et al 1988). Alteration of the electrophoretic banding pattern of one or more
enzymes was observed in 37 mutants. Such alterations were found for only three
enzymes—SDH-1, PGD-1, and PGI-2—among the 17 surveyed and were related to
mutations in apiculus color, grain shape, and plant height, respectively. Thus, for some
mutated characters, a linkage between mutated loci and isozyme loci might exist.
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