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Web End = J Chem Ecol (2015) 41:641650 DOI 10.1007/s10886-015-0599-1
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Web End = Spatiotemporal Floral Scent Variation of Penstemon digitalis
Rosalie C. F. Burdon1 & Robert A. Raguso2 & Andr Kessler3 & Amy L. Parachnowitsch1
Received: 20 March 2015 /Revised: 2 June 2015 /Accepted: 9 June 2015 /Published online: 2 July 2015 # Springer Science+Business Media New York 2015
Abstract Variability in floral volatile emissions can occur temporally through floral development, during diel cycles, as well as spatially within a flower. These spatiotemporal patterns are hypothesized to provide additional information to floral visitors, but they are rarely measured, and their attendant hypotheses are even more rarely tested. In Penstemon digitalis, a plant whose floral scent has been shown to be under strong phenotypic selection for seed fitness, we investigated spatiotemporal variation in floral scent by using dynamic headspace collection, respectively solid-phase microextraction, and analyzed the volatile samples by combined gas chromatographymass spectrometry. Total volatile emission was greatest during flowering and peak pollinator activity hours, suggesting its importance in mediating ecological interactions. We also detected tissue and reward-specific compounds, consistent with the hypothesis that complexity in floral scent composition reflects several ecological functions. In particular, we found tissue-specific scents for the stigma, stamens, and staminode (a modified sterile stamen common to all Penstemons). Our findings emphasize the dynamic nature
of floral scents and highlight a need for greater understanding of ecological and physiological mechanisms driving spatio-temporal patterns in scent production.
Keywords Diel variation . Floral scent . Nectar scent . GC/ MS . S-(+)-linalool . Pollen odor . Staminode
Introduction
Plants emit a variety of floral volatile compounds (Knudsen et al. 2006) enabling them to communicate and interact with mutualist pollinators (Raguso 2008a; Wright and Schiestl 2009) and antagonists, such as florivores (Kessler et al. 2013) and herbivores (Kessler and Baldwin 2007; Theis and Adler 2012). However, the chemical composition of floral scent is not static. Spatiotemporal variability in the identity and complexity of scent bouquets could provide critical information for the mediation of plant-animal communication because floral visitors can use subtle differences in volatiles to make foraging choices (Wright...