To facilitate an active breeding strategy for rice quality improvement, mutation were induced by treating rice variety Sindongjin seeds with gamma ray(300 Gray) and its fertilized eggs with MNU(1mM). Endosperm and grain shape of mutants were classified and selected in M2 population. From M2 generation, 48(7.6%) endosperm mutants and 179(11.9%) grain shape mutants were selected. White belly and White core were the most frequent. Selected grain mutants were classified into 16 types according to their morphological phenotypes. The overall segregation ratio was 3 : 1, controlled by one gene. Specially, SM-17 and SM-20 displayed segregation ratio of 9 : 7 and 1 : 15 respectively. Grain mutants showed generally earlier heading dates, shorter culm length and ear length than the parent. Grain length, grain width, and 1,000 grain weight were also mostly shorter and lower than the parent. In SEM analysis, each mutant type showed unique starch particle size and starch accumulation pattern. The density of polygonal cells and small inner corpuscles depending on amylose content decreased as following order - Waxy>Dull>Parent >White core. In SDS-PAGE analysis, SM-22 of Opaque group and SM-34 of Giant embryo group showed high glutelin polypeptide concentration. SM-23 of Floury group, SM-26 of Shrunken group, and SM-31 of Sugary group showed low concentration of total protein with variations in bands over 55kDa.

Various mutants of specialty rice were derived from Ilpumbyeo, a high-quality japonica rice cultivar, through muta-tion breeding by MNU treatment on fertilized egg cells of rice spikelets. The selected mutants revealed glutinous, semi-glutinousfthem were