21. Genetic variation of glutelin seed storage protein in Myanmar local rice cultivars

Laboratory of Plant Genetic Resources, Kyushu University, Faculty of Agriculture, Hakozaki, Fukuoka, 812-8581 Japan

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

was the same as Kinmaze (lane 1); type 2 had an extra band in the acidic position while the other bands of type 2 were the same as Kinmaze (lane 2). Type 3 was the same as IR36 (lane 3). Type 4 showed that bands 1 and 6 were present but bands 2, A and B were absent (lane 4). In type 5, bands 5 and 6 were present (lane 5). Some variations were also found in the site of glutelin beta subunit. Bands A and B of glutelin beta subunit were found in Kinmaze but not in IR36. However, these bands were also found in type 6 while the other bands of type 6 were the same as IR36 (lane 6). Frequencies of type 1 to 6 were 0.6%, 0.6%, 81%, 0.6%, 1.2% and 16% of total cultivars, respectively. This data indicates that types 2, 4, 5 and 6 of Myanmar local rice cultivars, which were different from that of Kinmaze and IR36, may be recombinant between IR36 type and Kinmaze type. IEF types 1, 2, 3, 4, 5 and 6 were found in SDS-PAGE type A, while IEF types 3, 5 and 6 were observed in type B. Myanmar local rice cultivars were different from the band patterns of typical varieties (Kinmaze and IR36). However, IEF band patterns of Myanmar local rice cultivars showed overlapping variation. The result indicates that Myanmar local rice cultivars are widely diverse in glutelin seed storage protein by IEF analysis.


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Krishnan, H.B. and T.W. Okita, 1986. Structural relationship among the rice glutelin Polypeptides. Plant Physiol. 81: 748-753.

Laemmli, U.K., 1970. Cleavage of structural proteins during the assembly of the head of Bacteriophage T4. Nature 227: 680-685.

Wen, T.H., and D.S. Luthe, 1985. Biochemical characterization of rice glutelin. Plant Physiol. 78: 172-177.