VARIATION IN SEED PROTEINS FROM MUTAGEN-TREATED CULTIVARS AND SELECTED LINES OF VIGNA-UNGUICULATA L. WALP

The storage protein profiles of the seeds of two IITA cowpea cultivars ('IT84E-124' and 'Vita 7') exposed to three mutagens - sodium azide ( NaN3), ethyl methane sulphonate (EMS) and Co-60 gamma rays - and those of 18 selected M-3 lines were investigated by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis (PAGE). The total seed prote in, globulin and albumin fractions showed differences in number and in tensity of subunit bands, but the least differences were found in the albumin fraction. Both high and low molecular weight bands were observ ed, the highest being 94.5 kDa and the lowest 12.0 kDa. 'Vita 7' showe d less variability compared with 'IT84E-124', as indicated by the rela tive similarity indices (S.I.) of the two cultivars. The lowest S.I. o f 0.200 was found among 'IT84E-124' lines while the lowest S.I. among 'Vita 7' lines was 0.4706. A number of lines with particular traits we re found to be characterized by the presence of specific polypeptide b ands. This study demonstrates that induced mutation could create addit ional variability to supplement existing germplasm and that SDS-PAGE i s a useful tool for discriminating and estimating genetic similarities among selections.