Seed storage protein diversity is important for breeding improved nutritional quality of rice and for the varietal identification. Rice glutelin is composed of two major subunits: an acidic subunit (alpha subunit) with molecular mass of 40 kD and a basic subunit (beta subunit) with molecular mass of 20 kD (Wen and Luthe 1985; Krishnan and Okita 1986). This paper deals with the genetic variation of a seed storage protein, glutelin, observed in Myanmar local rice cultivars.

One hundred and fifty local rice cultivars collected from six distinct regions, obtained from Seed Bank of Myanmar, were analyzed by SDS-PAGE and IEF. japonica cultivar Kinmaze and indica cultivar IR36 were used as control. SDS-PAGE was carried out using the discontinuous buffer system of Laemmli (1970). IEF gels were prepared and used as described by Brinegar and Peterson (1982). Gels were composed of 8.5M urea, 30% acrylamide, 1.5% bisacrylamide, 20% Nonidet P-40 and 2% ampholine with pH (3.5 -10): (6 -8): (8 -10.5) = 1:1:1.

In the SDS-PAGE analysis two types of variation for glutelin alpha subunit were detected in Myanmar local rice cultivars, based on molecular mass of alpha-3 band. Type A was characterized by low molecular mass of alpha-3 band, the same as Kinmaze. Type B showed high molecular mass of alpha-3, similar to IR36 (Fig. 1). Their respective frequencies were 43% and 57% of total cultivars.

The banding patterns by SDS-PAGE analysis could not explain the prospect of gene coding for glutelin molecule because each of the SDS-PAGE bands consists of more than two IEF bands. Glutelin alpha-subunit bands were numbered 1 to 12 and beta subunit bands were labeled A to I. Variation in IEF banding patterns was compared with standard varieties, Kinmaze and IR 36. In Kinmaze, bands 1, 5, A and B were present but bands 3 and 6 were absent (Fig. 2). In contrast, bands 3 and 6 were present in IR36 while bands 1, 5, A and B were absent. Type 1