Glutelin, a major storage protein in rice, is synthesized as 57kD proglutelin on the rER, transported to the vacuole via the Golgi apparatus, and formed by proteolysis of the proglutelin through post-translational cleavage into acidic (alpha) and basic (beta) subunits in the vacuole (Yamagata et al. 1982, Takaiwa et al. 1986, Masumura et al. 1989). Uemura et al. (1996) reported that sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF) gel electrophoresis are useful to detect the variation of glutelin seed storage protein. Kagawa et al. (1988) found the variation in glutelins of local rice cultivars by SDS-PAGE analysis. Satoh et al. (1990) reported that a large variation exists in glutelin polypeptides in rice collected in Tanzania. This report deals with the variation of glutelin polypeptides in rice cultivars of Bangladesh, an area considered to be one of the centers of origin of cultivated rice (Chatterjee 1951).

Five hundred and seventy six Bangladesh rice cultivars preserved at the Laboratory of Plant Genetic Resources, Kyushu University, Japan, were used in this study. Extracted proteins were separated by SDS-PAGE using the discontinuous buffer system of Laemmli (1970) on a slab gel containing a linear of 15% to 25% acrylamide, 0.05 to 0.67% BIS concentration gradient. Rice glutelin was composed of alpha and beta subunits, which were separated into alpha-1 (39 kD), alpha-2 (38 kD), alpha-3 (37.5 and 37 kD)and alpha-4 (34 and 33 kD) for alpha subunit and beta-1 (23 kD), beta-2 (22.5 kD) and beta-3 (22 kD) bands for beta subunit, respectively. Uemura et al. (1996) reported that the alpha-3 band of Japanese rice cultivar Kinmaze is smaller in molecular size than that of rice cultivar IR36 developed at IRRI, while the alpha-4 (34 kD) band of Kinmaze is larger than that of IR36 (33 kD). Bangladesh rice cultivars varied significantly in SDS-PAGE profiles of glutelin storage protein. In addition to 'Kinmaze' (type 1) and 'IR36' (type 5) types, mutant types with decreased alpha-2 band and with two alpha-3 bands were observed (Fig. 1). One mutant