Characterisation of okra (abelmoschus [medik.]) accessions using dehydrogenase isozymes and protein

Abstract

Okra (Abelmoschus [Medik.]) is cultivated in distant farms and home gardens on a commercial or subsistence scale in tropical and subtropical regions of the world. Several diverse cultivars exist but they all possess a characteristic mucilaginous substance. Isozymes are enzymes composed of different structural amino acid sequence but may catalyse similar chemical reaction. In chemosystematics isozymes and other phytochemicals may be used to characterize plant germplasm. This study employed dehydrogenase isozymes and total protein to characterize Abelmoschus accessions. Five Abelmoschus accessions including 2 A. esculentus (NG/OA/03/12/157 and NG/OA/05/12/159) and 3 A. caillei (NG/OA/03/12/158, NG/SA/DEC/07/0475 and NG/SA/DEC/07/0482) species were collected from the National Center for Genetic Resources and Biotechnology Ibadan and cultivated at the Experimental fields of University of Benin, Nigeria. At maturity, fruits were harvested for analysis at the Biochemistry Division, Nigeria Institute of Medical Research, Lagos. Results showed that variation exist in the quantity of total protein in the five accessions with accessions, NG/SA/DEC/07/0475, NG/SA/DEC/07/0482 and NG/OA/03/12/158 having higher values (33.076 g, 31.210 g and 28.992 g respectively) compared to NG/OA/03/12/157 and NG/OA/05/12/159, which had low values of total protein content (21.227 g and 9.429 g respectively). Isozyme activities of alcohol, malate and isocitrate dehydrogenases showed distinctive results. Significance results (at P < 0.05) were obtained with accessions NG/OA/03/12/157 and NG/OA/05/12/159 having higher values when compared with accessions NG/SA/DEC/07/0482, NG/OA/03/12/158and NG/SA/DEC/07/0475. When homogeneity was compared accessions NG/SA/DEC/07/0482, NG/OA/03/12/158 and NG/SA/DEC/07/0475 were found to be in the same category, while accessions NG/OA/03/12/157 and NG/OA/05/12/159 in separate categories. The degree of intra specific variation differ for the five accessions. Grouping of the A. caillei accessions in one cluster suggest a within species similarity. Nevertheless, the separation of a single cluster for A. esculentus accessions may suggest a considerable degree of total protein content and isozymatic variation within the species. The isozyme characterization has proven effective in the identification and characterization of these Okra accessions but activities of these isozymes only cannot be used as an indication of evolutionary advancement and classification at the generic and species level.