Identification of cowpea cultivars (Vigna unguiculata (L) Walp) by isoenzyme electrophoresis

Abstract

The differences among cowpea (Vigna unguiculata (L) Walp) cultivars were identified using electrophoretically detected isozymic variability. The enzymes studied in the selected 10 cultivars of cowpea were Diaphorase (DIAP), Phospho Gluco Isomerase (PGI), 6Phospho Gluconate Dehydrogenase (6PGD), Phospho Gluco Mutase (PGM), Esterase (EST), Hexose Kinase (HK) and Glucose Oxalo Acetate Transaminase (GOT). Starch gel electrophoresis was used to analyze extracts prepared from young leaf tissues of seven day old seedlings of each cultivar grown under greenhouse conditions. Three enzymes GOT, HK, and PGM exhibited two patterns, while three different patterns were observed for EST and 6PGD. Phospho Gluco Isomerase showedfour different patterns, and DIAP appeared to be the most polymorphic with eight patterns. Distinct variety specific zymograms were observed for several enzymes. Unique combinations of isozymic variants of two enzyme systems assayed (DIAP and PGI) could differentiate all the culti*urs. Sufficient variability was present in cowpea cultivars to allow the use of isozyme electrophoresis as a method for cultivar identification. Therefore, ii could be used in variety identification to complement the morphological characters.