Phylogenetic Relationships of Five Genera in the Family Araceae Inferred from Plastid DNA Nucleotide Sequences

Abstract

Aims: To assess the phylogenetic relationships and genetic diversity among selected Araceae taxa in Southwestern Nigeria using plastid DNA sequences, and to determine their evolutionary relationships and taxonomic placement. Study Design:  A molecular phylogenetic study based on plastid DNA sequence analysis. Place and Duration of Study: Plant samples were collected from various locations in Southwestern Nigeria; laboratory analyses (DNA extraction and purification, Polymerase Chain Reaction (PCR), DNA sequencing, and phylogenetic analysis) were conducted over the study period of one year. Methodology: Sixteen species from five genera (Aglaonema, Dieffenbachia, Alocasia, Colocasia, and Xanthosoma) were analyzed, with two Philodendron species as outgroups. Plastid DNA regions (trnL–F, rpl32–trnL, and trnV–ndhC intergenic spacers) were sequenced following standard protocols. Bayesian inference was used to construct phylogenetic trees, with posterior probabilities assessing clade support. Results: The phylogenetic tree constructed from over 2,000 base pairs revealed the monophyletic status of the five genera studied and resolved the taxa into four major clades consistent with existing tribal and generic classifications within Araceae. The tree topology showed strong Bayesian posterior probability support, indicating reliable evolutionary relationships among the taxa. Colocasia, Alocasia, and Xanthosoma occupied relatively basal positions in the phylogeny, while Aglaonema and Dieffenbachia appeared to be more recently evolved. Intrageneric relationships among taxa were also clearly established. Conclusion: Plastid DNA markers effectively resolved phylogenetic relationships among the studied Araceae taxa. The findings validate existing tribal and generic classifications and provide insights into the evolutionary relationships of economically and medicinally important aroids in Nigeria.