Application of new technologies to rice breeding

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For the application of new technologies such as cell fusion and gene manipulation to rice breeding, it is necessary to accumlate the knowledges of molecular level in rice plants and also to improve the technologies in tissue culture. After getting gene-manipulated plants, an efficient selection system for improving to a new variety should be required.1. The cDNA library on poly <(A)^+> RNA which related to the synthesis of rice storage protein, glutelin and prolamin, was established. It was clearified that the storage protein in endosperm formed two kinds of granules, protein body <I> and <II> , and nondigestable protein body <I> mainly consisted prolamin.2. A physical map of rice chloroplast DNA was established and the location of the genes for large subunit of Rubisco and the subunits of ATPase was proved. The base sequences of the genes were also determined. On the mitocondorial DNA, cloning of all DNA fragments was succeeded and a fragment having activity of autonomously replicating sequence was found out.3. Adventive shoot formation and somatic embryogenesis from callus induced from seeds and pollen were investigated using many varieties, and genotypic variability in plant regeneration was clearified. On the basis of the results, plant regeneration was succesively induced from protoplasts originated from seed callus.4. Characteristics of mutator gene obtained from progenies of slender grain mutant was analyzed and strong effect of the gene as amutagen was clearified. New sugary and shrunken mutants were obtained by treating fertilized egg cells with nitroso compounds.5. Gene expression of semi-dwarfness of Dee-geo-woo-gen type was investigated in internode elongation, and also phenotypic expression of drought resistance and cooking quality were analyzed in their related characters.