Genetic characterization of Jatropha landraces in Nigeria: unlocking potential through rbcl marker analysis

Jatropha is a medicinal plant commonly found in many parts of Nigeria, but despite its usefulness, its genetic resources have not been fully explored. While different Jatropha species have been studied in several countries, there is still very little information available on the genetic diversity of Nigerian landraces. In this study, forty Jatropha landraces were collected from different locations and identified using their local names as well as visible morphological features recognised by local farmers. Fresh leaf samples from the collected landraces were analysed using the rbcL gene for genotyping and sequencing. The resulting data were further examined using Analysis of Molecular Variance (AMOVA) in GenALEx 6.5, phylogenetic analysis based on the Neighbour-Joining method, and SNP detection with DnaSP software. The results of the phylogenetic analysis separated the landraces into three major clusters, although the clustering pattern did not correspond to their geographical locations. This suggests the existence of substantial genetic variation among the landraces. A total of 685 mutations and 39 haplotypes were detected, with a very high haplotype diversity value of 0.999. This high level of diversity may be linked to mutation and recombination events within the population. In addition, nucleotide diversity was relatively high (0.70410), further indicating considerable genetic differences among the sampled landraces. AMOVA results showed that only 1% of the total variation occurred among populations, whereas 99% existed within populations, revealing a high level of diversity at the local population level. These findings provide useful baseline information for future conservation efforts and for the selection of promising parent materials in Jatropha breeding programmes.