title: Scent emission profiles from Darwin's orchid--Angraecum sesquipedale: Investigation of the aldoxime metabolism using clustering analysis.
abstract: The display of scent is crucial for plants in attracting pollinating insects to flowers and ensuring successful pollination and reproduction. The large number of aldoxime volatile species present in the scent of the Madagascan orchid Angraecum sesquipedale has been suggested to play a primary role in attracting the sphingid moth Xanthopan morgani praedicta. By solid phase micro-extraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS), we monitored the scent release from different flowers of a single orchid, day and night throughout the entire flowering period. In separate experiments, the diurnal release was monitored in 3h intervals and the tissue specific release from the different floral parts was tracked. Numerous novel compounds related to the aldoxime metabolism not previously detected in A. sesquipedale were identified and positioned into a proposed pathway for aldoxime metabolism. From the results, we hypothesize that (E/Z)-phenylacetaldoxime and its derivatives could be important attractants for the pollinating moth X. morgani praedicta. By applying an untargeted Partitioning Around Medoids (PAM) cluster analysis to the metabolite profiles in the scent, the proposed pathways for the formation of aldoximes were substantiated. With this study, we demonstrate the powerful utility of a bioinformatics tool to aid in the elucidation of the routes of formation for volatiles and provide a benchmark and guidelines for future detailed observations of hawkmoth pollination of Angraecum species, and in particular A. sesquipedale, in the wild.
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Copenhagen, Frederiksberg, Denmark; VILLUM Research Center of Excellence "Plant Plasticity", University of Copenhagen, Thorvaldsensvej 40, DK-1871 Copenhagen, Frederiksberg, Denmark.
authors.forename: Lasse Janniche
authors.initials: LJ
authors.lastname: Nielsen
authors.affiliation: Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, DK-1871 Copenhagen, Frederiksberg, Denmark; VILLUM Research Center of Excellence "Plant Plasticity", University of Copenhagen, Thorvaldsensvej 40, DK-1871 Copenhagen, Frederiksberg, Denmark. Electronic address: blm@plen.ku.dk.
authors.forename: Birger Lindberg
authors.initials: BL
authors.lastname: Møller
mesh_terms: D000818:Animals; D035264:Flowers / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D015394:Molecular Structure; D009036:Moths / Q000502:physiology; D029595:Orchidaceae / Q000737:chemistry*; D010091:Oximes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010675:Pheromones / Q000502:physiology; D054817:Pollination / Q000502:physiology; D012098:Reproduction; D013237:Stereoisomerism; D055549:Volatile Organic Compounds / Q000032:analysis / Q000737:chemistry
chemical_list: D010091:Oximes; D010675:Pheromones; D055549:Volatile Organic Compounds; C010411:insect attractants; C408881:phenylacetaldoxime
keywords: Angraecum species; Cluster analysis; Floral scent; Headspace analysis; Nitriles; Pollination; Solid phase micro-extraction; Sphingid moth; Xanthopan morgani praedicta