Molecular Characterization of 36 Accessions of Two Genera of Cocoyam (Colocasia [Schott] and Xanthosoma [Schott], Araceae)

Abstract

Most popular edible aroid commonly called cocoyam belong to the genera Colocasia (Schott) and Xanthosoma (Schott); are tuber crops introduced into Africa from Asia and tropical America respectively. These crops are grown in all parts of tropical and sub-tropical regions where they have high adaptability, acceptance and serve as auxillary crop plant for food income security. The present study aims to collect cocoyam germplasm from local agriculture systems in Edo state, Nigeria and characterize them using molecular marker techniques. Random stratified sampling method was used to collect the plant genetic resources based on IBPGR and IPGRI descriptors. Collecting cocoyam germplasm is first reported in Nigeria in this study. Collected germplasm were planted out for trial in a home garden plot situated in the University of Benin, Nigeria. After 6 months, leaves were harvested for Random Amplified Polymorphic DNA (RAPD) analysis to characterize the accessions. RAPD-PCR was conducted at Biochemistry Division, Nigerian Institute of Medical Research (NIMR), Yaba-Lagos state. Differences in the pattern of bands pro after gel electrophoresis reveal the crops are diverse within the state. Dendrogram constructed from the data matrix suggests two trees with varied number of lines. These lines were inferred as different varieties of the species of the two genera. Some of the accessions precisely IA, HD, BB and JC were not clustered into any group. This suggests that these accessions are unique and distinct within and between the two genera of cocoyam. The  banding pattern were similar within species and different between species, but was not able to distinguish all the varieties from one another. Cluster analysis gave 8-10 groups in two branches corresponding to specific associations with little filtration observed among these groups. The dendrogram implicates accession BB as been unique among all the thirty six accessions studied. Its intermediate response suggests either a branch off point or pure line. Jaccard’s similarity clustered the accessions into six groups. The RAPD-PCR could swerve as a basis for other characterization works on the 36 accessions of cocoyam for the basis of conservation and sustainable utilization