Phenoplasticity of Essential Oils from Two Species of Piper (Piperaceae): Comparing Wild Specimens and Bi-Generational Monoclonal Cultivars

This study tested the hypothesis that "clonal chemical heritability is a crucial factor for the conservation of chemical uniformity of Piper essential oils in controlled monoclonal cultivation". We asexually propagated first and second-generation clones of two medicinal and aromatic species, Piper gaudichaudianum Kunth and Piper mollicomum Kunth (Piperaceae), for use as experimental models since they show high chemical plasticity in the wild. Leaves from wild specimens of both species, and their respective cultivated specimens, were hydrodistilled in a Clevenger-type apparatus to produce essential oils (EOs). EOs were chemically characterised by GC-MS and GC-FID. The analysis identified 63 compounds in EO of P. mollicomum, which were predominantly monoterpenes, and 59 in EO of P. gaudichaudianum, which were predominantly sesquiterpenes. Evaluation of chemical diversity and oxi-reduction indices showed a loss of chemical homology across the intergenerational cline. Chemometric analysis indicated higher chemical plasticity between wild and intergenerational specimens of P. mollicomum, than for P. gaudichaudianum. EO compounds were significantly less oxidized throughout the generations in both species. Therefore, while clonal heritability is crucial to chemical homology, significant chemical plasticity is likely to occur when cultivated from wild specimens.