Genetic variation of glutelin acidic subunit polypeptides in Bangladesh rice genetic resources

Bangladesh rice genetic resources collected from six distinct regions of the country were examined to obtain the diversity in glutelin acidic subunit polypeptides. Seed glutelins from 576 Bangladesh rice cultivars representing seven ecotypes were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), isoelectric focusing (IEF) electrophoresis and two-dimensional electrophoresis (2-DE: SDS-PAGE/IEF) analyses. Glutelin acidic subunit was separated into four bands, alpha-1, alpha-2, alpha-3 and alpha-4, and the variation in each of bands was detected by SDS-PAGE analysis. A higher molecular size component of alpha-1(alpha-1') was identified in the cultivars tested. In case of alpha-2, alpha-2H with high molecular mass, alpha-2L with low molecular mass and alpha-2H/L were detected. alpha-3 band variation showed alpha-3H, alpha-3L, and alpha-3H/L, while for alpha-4, alpha-4H, alpha-4L bands were identified. In IEF analysis, a total of 16 bands with independent pI ranging from pI 6.30 to 7.52 were identified for the glutelin acidic subunit among the cultivars. The maximum and minimum numbers of IEF bands found were 13 and 9, respectively. The alpha-2L less cultivars were also lacking in pI 6.80 polypeptide in IEF. Result of 2-DE showed that pI 6.80 polypeptide was the main component of alpha-2L band. Transplanted Aman ecotype was the most diverse with respect to glutelin variation. Geographical distribution of glutelin variation in the Transplanted Aman ecotype differed according to the regions. The above results indicate that Bangladesh rice cultivars possess great genetic diversity in glutelin acidic subunit polypeptides. This study of indigenous rice cultivars from Bangladesh provides useful information regarding their breeding potential.