Abstract
The volatile fraction of Ophrys sphegodes Mill. subsp. sphegodes, Ophrys bertolonii subsp. benacensis (Reisigl) O. Danesch, E. Danasch & Ehrend. and Neotinea tridentata (Scop.) R.M. Bateman, Pridgeon & M.W. Case, three orchid species with different pollinator attraction strategies, sampled in vivo and in situ, were evaluated by headspace solid phase microextraction coupled with gas-chromatography and mass spectrometry. The results were compared with the volatile compounds emitted by flowering plant samples picked from the same populations of orchid species. Hydrocarbons, aldehydes, alcohols and terpenes were the major constituents of “in vivo” orchid scents and some distinctive differences in volatile metabolite composition were observed between Ophrys and Neotinea species. Moreover, the odour bouquets of the picked flowering plant samples were different from the in vivo ones and in particular different proportions of the various terpenes and an increase of α-pinene were observed. In conclusion HS/SPME GCMS proved to be a suitable technique for analyzing and distinguishing the volatile fingerprint of different orchid species, sampled in vivo and in situ in a non-disruptive way, with potentially great advantages for ecophysiological studies of rare and endangered species.
Highlights
Investigation into plant and flower scents represents an important field of modern research directed at special biological recognition theories
The scent of a flower is often a complex blend of secondary volatile metabolites, and together with colour and shape is considered to be the main signal attracting pollinators [1,2,3,4], which in turn affect the reproductive performance of plants, their relationships with the environment and, their conservation
Many orchid species provide nectar, but other species are deceptive, so they attract pollinators in different ways, the most common strategies being mimicry of nectariferous flowers (e.g., Orchis, Neotinea, Anacamptis), sexual deception (e.g., Ophrys) and provision of shelter (e.g., Serapias) [5]
Summary
Investigation into plant and flower scents represents an important field of modern research directed at special biological recognition theories. The variety of shapes, colours and scents present in orchids is seldom found in other plant families. These characteristics contribute to the unique strategies used by orchids to attract pollinators. Many orchid species provide nectar, but other species are deceptive, so they attract pollinators in different ways, the most common strategies being mimicry of nectariferous flowers (e.g., Orchis, Neotinea, Anacamptis), sexual deception (e.g., Ophrys) and provision of shelter (e.g., Serapias) [5]. Food-deceptive orchids mimic rewarding species, some with specific models (e.g., Disa) others with flowers that have the typical characteristics of rewarding plants (i.e., nectar guides, spur, etc.) (e.g., Orchis, Neotinea, Anacamptis) [9]. Ophrys species have evolved a high degree of pollinator specificity, while Neotinea species are more generalist
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