1) National Institute of Agrobiological Resources, Yatabe, Tsukuba Science City, 305 Japan
2) College of Agriculture, University of the Ryukyus, Nishihara, Okinawa, 903- 01 Japan
Comparison of mitochondrial DNAs (mtDNAs) and chloroplastDNAs is one of the
fundamental approaches to elucidate the mechanism of cytoplasmic male sterility
(cms). Molecular analyses of mtDNA have been actively pursued in many plants
(Pring and Lonsdale 1985). On the other hand, analysis of rice mitochondrial
chromosomal DNA has not been documented yet, except for two reports dealing
with the plasmid-like DNAs in cms rice (Yamaguchi and Kakiuchi 1983; Nawa et
al. 1985).
We have isolated mtDNA from rice leaves and analysed its restriction fragment patterns by agarose gel electrophoresis (Kadowaki et al. 1986). The restriction fragment pattern of the mtDNA of cms-Bo Taichung 65 was found to be significantly different from that of normal Taichung 65, and the mt DNA of cms- R Reimei was different from that of normal Reimei. It is noteworthy, moreover, that the mtDNAs isolated from cms-Bo, cms-R and WA cytoplasms were different from one another in their restriction fragment pattern. This result indicates that each male sterile cytoplasm has a different type of mtDNA. We are currently analysing mtDNAs of other cms rice strains and will classify their cytoplasms into several groups based on the restriction fragment pattern analysis.
References
Kadowaki, K., T. Ishige, S. Suzuki, K. Harada and C. Shinjyo, 1986. Differences in the characteristics of mitochondrial DNA between normal and male sterile cytoplasms of Japonica rice. Jpn. J. Breed. 36: 333-339.
Nawa, S., Y. Sano and T. Fujii, 1985. Analysis of mitochondrial DNA in cytoplasmic male sterile rice. RGN 2: 98-99.
Pring, D.R. and D.M. Lonsdale, 1985. Molecular biology of higher plant mitochondrial DNA. Int. Rev. Cytol. 97: 1-46.
Yamaguchi, H. and H. Kakiuchi, 1983. Electrophoretic analysis of mitochondrial DNA from normal and male sterile cytoplasms in rice. Jpn. J. Genet. 58:L 607- 611.