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An investigation was carried out on 52 accessions of cowpea to determine the variation in their storage seed protein subunit bands profile obtained through Sodium Dodecyl Sulphate - Polyacrylamide Gel Electrophoresis (SDS-PAGE). The proteins were extracted from cotyledons to represent both water and salt soluble proteins. Results revealed that protein subunit bands ranged between 97.4 kD to less than 18.4 kD molecular weight(MW). The bands of the accessions could be placed in five distinct regions. Those of region I and II were monomorphic and intensely stained and identified to range between 97.4 kD to 43.0 kD. The bands of region III and IV were relatively more polymorphic than those of region V. These bands were in the MW range of 43.0 kD to 10.0 kD. The binary data generated from the polymorphic bands over the accessions were used to compute Jaccard’s similarity coefficients. The similarity matrix thus prepared was used to construct a dendrogram which, in turn, distributed the accessions in seven clusters. One of the accessions, was most diverse from the rest. Cluster I was comprised of three accessions with mottled seed coat color whereas in a sub cluster of cluster 7 two mutant derivatives of same parent were included. Cluster 2 showed a sub cluster of three accessions with very small seed weight and volume as well. Rest of the clusters did not reveal any characteristic similarity among their accessions.
Keywords: Cowpea, Genetic diversity, SDS-PAGE, seed storage proteins.