Floral Scent Variation in Cyrtorchis letouzeyi (Orchidaceae) Between Natural Versus Cultivated Environments

Abstract

In the tropics, one successful tool for orchid scientific studies and conservation is the creation of shade houses for ex situ cultivation of regional species. Here, we provide the first comparison of floral scent chemistry in shade houses and natural populations of orchids in central Africa. We investigate floral scent variations between two shade houses and one natural site in a sphingophilous epiphytic orchid, Cyrtorchis letouzeyi, in Cameroon. Samples were collected in and ex situ through the dynamic headspace method and analyzed using gas chromatography coupled with mass spectrometry. Both composition and relative emission rate were analyzed with temperature and humidity levels recorded at the time of sampling. The floral scent was dominated by both aromatics and isoprenoids and derivatives, including methyl benzoate, linalool, and pyranoid and furanoid forms of linalool oxide. Variations in temperature and humidity had no significant impact on the floral scent composition but on relative emission rates. Samples under shade house cultivation produced the same compounds as those in the natural environment. Quantitatively, differences were recorded in the proportions of volatile organic compounds (VOCs) produced, but the main compound remained unchanged in both environments. Dissimilarities were driven by the production of linalool and its derivatives. Based on these findings, we suggest that shade houses are a suitable tool to characterize the qualitative floral scent diversity of tropical epiphytic orchids and can therefore serve to complement in situ sampling.