Characterization of seed storage proteins in high protein genotypes of cowpea [Vigna unguiculata (L.) Walp].

Twenty one genotypes and two check varieties viz. CS-88 and V-240 of cowpea [Vigna unguiculata (L.) Walp. ] were screened for total proteins. The total protein content ranged from 22.4 (HC-3) to 27.9 % (HC-98-64) in 21 genotypes whereas in check varieties it was 25.6 (V-240) and 26.0 % (CS-88). Seven genotypes viz. HC-6, HC-5, CP-21, LST-II-C-12, CP-16, COVU-702 and HC-98-64 having high protein content (26.7 to 27.9 %) were selected for further characterization of their seed storage proteins. Globulins were the major protein fraction ranging from 55.6 (LST-II-C-12) to 58.8 % (CP-16 and HC-6) of total protein. Glutelins was the second major fraction ranging from 14.4 to 15.6 % followed by albumins (8.2 to 11.9 %) and prolamins (2.3 to 5.0 %). Content of free amino acids also showed variations amongst genotypes with COVU-702 having maximum and LST-II-C-12 having minimum content. Essential amino acid analysis revealed that S-amino acids (cysteine and methionine) were the first limiting amino acids followed by tryptophan. From the results presented here it could be suggested that two genotypes viz. LST-II-C-12 and HC-5 be used in breeding programmes aimed at developing high protein moth bean varieties with good quality.