Evaluating genetic biodiversity of Parkia biglobosa (Jacq.) R. Br. Ex Don (African locust bean) accessions from Nigeria using seed protein electrophoresis

Abstract

Thirty-four accessions of African locust bean (Parkia biglobosa) collected from different localities across Nigeria were screened for variability in seed storage proteins. Globulin, albumin, and vicilin fractions were investigated by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE. Both methods of analysis revealed a substantial degree of heterogeneity in the protein fractions. However, native PAGE produced fewer protein bands and profiles than SDS-PAGE. Although accessions exhibited significant similarity in their polypeptide profiles, differences in migration rate and staining intensities as well as presence / absence of specific bands accounted for variations obtained in the accessions examined. The absence of 10 kDa albumin subunit was specific to accessions 24, 25, 26, and 29 while the presence of 30.4 kDa vicilin was unique to accessions 5, 6, and 7. One major cluster of globulin band between two polypeptides 42.7 – 50 kDa, and two minor bands 31.4 and 16.2 kDa were observed. Protein fraction profiles were in most cases not similar among the accessions collected from same agroecological zone. This suggests that gene flow between the different zones must have occurred due to movement of germplasm and exchange of genetic material among farmers and markets. Groupings based on cluster analysis and polypeptide patterns agree and confirm the presence of duplicates within the accessions studied.