Comparative Electrophoresis and Isozyme Analysis of Seed Proteins from Cultivated Races of Sorghum

Abstract

Comparative disc electrophoresis of acidic proteins, basic proteins, and isozymes of esterase, MDH, and peroxidase were performed with aqueous extracts of seeds from seven cultivars belonging to five races of Sorghum bicolor ssp. bicolor: bicolor, caudatum, durra, guinea, and kafir. Two disc electrophoretic systems were employed. Acidic proteins were electrophoresed in an anionic system (tris-glycine buffer, pH 8.3). Basic proteins were electrophoresed in a cationic system (β-alanin-acetate buffer, pH 4.5). Soluble proteins were stained with Coomassie brilliant blue. Isozyme activity was detected by using specific enzyme stains and substrates. Each cultivar yielded reproducible, characteristic patterns of distinct acidic and basic proteins. Cultivars belonging to the same race produced identical protein and isozyme patterns. The degree of electrophoretic similarity among races was estimated by calculating similarity index values for each of the 10 possible pairs of races. Bicolor, caudatum, durra, and guinea produced very similar acidic and basic protein patterns and esterase, MDH, and peroxidase isozyme patterns. Differences, however, were observed among all races. All of kafir patterns were significantly different from the patterns of other races. Comparative electrophoresis may provide a new source of taxonomic characters for investigating phenetic and phylogenetic relationships in Sorghum.