Abstract :
The study employs the SDS-PAGE electrophoretic techniques to evaluate the taxonomic implications of some species in the subtribe Cassiinae(Caesalpinaceae) using total leaf proteins. The aim was to assess the genetic variation and relationship among the 15 species of subtribe Cassiinaethrough electrophoretic studies of their leaf proteins. Total leaf proteins were extracted and separated on 12% polyacrylamide gels using standard protocols. Young leaves (0.8g) of the plants were washed with distilled water and macerated with sterile mortar and pestle in 0.8% Phosphate Buffer-Saline (PBS) containing 0.4M NaCl at PH 8.0. Results obtained revealed that protein pattern was taxon-specific as no two species have the same banding pattern. Distant polymorphism in electrophoretic banding patterns of the leaf was observed through a total of forty-one (41) polypeptide bands. Variation existed not only in the number of bands but also in the intensity of bands in the leaf samples studied. The coefficients of similarity range between 0.076 – 0.845. The hierarchical cluster analysis (dendrogram) for the 15 species revealed two major clusters. The first group are Senna spectabilis, S. alata, S. hirsuta, Chamaecrista rotundifolia, C. mimosoides, S. biflora and the second group are S. podocarpa, S. sophera, S. occidentalis, S. obtusifolia, Cassia italica, S. siamea, C. singueana, C. sieberiana and C. fistula. An artificial key for the studied species of subtribe Cassiinae based on their band relationships is also provided. Therefore, the number and intensity of bands are additional characters that can be used for species delimitation in subtribe Cassiinae.
Keyword :
Cassiinae; Clustering; SDS-PAGE; Leaf protein; delimitation