Electrophoretic Characterization of the Cowpea Mutants for Seed Storage Proteins [Vigna unguiculata (L.)Walp]

An investigation was carried out on 38 EMS derived M₆ generation mutants of two cowpea varieties RC-19 and RC-101 to determine their seed storage protein subunit profile variation through Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). These mutants have deviated from their respective parents for their seed coat color, size and shape. The proteins extracted from cotyledons represented both water and salt soluble proteins. The results of the SDS-PAGE revealed 18 protein subunit bands in the range of 97.4 kD to ∼14 kD molecular weight (MW). The protein bands could invariably be placed in five distinct regions. Only certain bands of region III and IV were polymorphic. The binary data generated from the polymorphic bands over the genotypes (parents and mutants) were used to compute Jaccard's similarity coefficients using NTSYS-pc software. The similarity matrix thus prepared was used to construct a dendrogram by UPGMA. The dendrogram distributed the 30 mutants of RC 101 and 8 mutants of RC 19 into 11 and 5 minor clusters, respectively. However, for both group of mutants two major clusters were apparent. One mutant in each group assumed unique place. The cotyledonary protein content of the mutants was invariably reduced as compared to their parents and ranged from 21–30.3%.