SEED PROTEIN ELECTROPHORETIC CHARACTERIZATION OF COWPEA (VIGNA-UNGUICULATA) GERMPLASM FROM IITA GENE BANK

The total seed protein, globulin and albumin fractions of 20 cowpea (V . unguiculata) accessions from IITA gene bank were investigated by SDS -polyacrylamide gel electrophoresis. Total seed protein extracts were prepared from the defatted meal by homogenisation and centrifugation i n Tris-glycine buffer. The globuIins and albumins were obtained from t he total protein extract by exhaustive dialysis against sodium acetate buffer. Two main total seed protein electrophoretic patterns were obs erved with respect to the 39 and 20 kD subunits, which were present in six out of the twenty accessions analysed. While there was no correla tion between seed colour and total seed protein banding pattern, the s ix insect-resistant cultivars were characterized by the presence of th e 39 and 20 kD subunits. The globulins were the predominant class of t he total seed proteins and consisted mainly of 64, 58, 56 and 14 kD su bunits which make up CP1 and CP2, the major globulins. The albumins in all accessions were a heterogeneous protein fraction consisting of bo th high and low molecular weight subunits. It was suggested that the i nsect-resistant cultivars may be genetically related and that the 39 a nd 20 kD subunits may be involved in the insect resistance mechanism.