Genetic and Morphological Analyses of Native Vanilla Populations in Mexico Call into Question the Taxonomy of V. odorata

Wild vanilla populations with high aromatic potential and morphological affinity to Vanilla odorata have been identified in Oaxaca, Mexico. This study employed morphologic and molecular taxonomic approaches to characterize plant material collected from the field and subsequently maintained under uniform conditions at the Tecnológico Nacional de México Tuxtepec campus germplasm bank. Morphological characterization of the three populations was conducted, and genetic analyses of 155 accessions (2365 SNPs) were performed using Genotyping by Sequencing. The morphological analyses revealed clear differences in vegetative and reproductive traits among the studied accessions. Phylogenetic and STRUCTURE analyses identified three groups within the V. odorata-like clade: a pure group, and two hybrid groups involving V. odorata and V. insignis or V. cribbiana. These findings reveal a high level of phenotypic and genetic diversity within wild vanilla populations from Oaxaca and suggest that hybridization may have played an important role in the evolutionary history of the group. Furthermore, the results challenge the current taxonomic circumscription of Vanilla odorata, indicating that its taxonomic identity and evolutionary origin require re-evaluation. This study provides new insights into the diversification and taxonomy of aromatic wild vanilla species in Mesoamerica.