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Phytochemistry

Title:		Colour-scent associations in a tropical orchid: three colours but two odours
Author(s):		Delle-Vedove R; Juillet N; Bessiere JM; Grison C; Barthes N; Pailler T; Dormont L; Schatz B;
Address:		"Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR CNRS 5175, Montpellier, France. roxane.delle-vedove@cefe.cnrs.fr"
Journal Title:		Phytochemistry
Year:		2011
Volume:		20110304
Issue:		8
Page Number:		735 - 742
DOI:		10.1016/j.phytochem.2011.02.005
ISSN/ISBN:		1873-3700 (Electronic) 0031-9422 (Linking)
Abstract:		"Colour and scent are the major pollinator attractants to flowers, and their production may be linked by shared biosynthetic pathways. Species with polymorphic floral traits are particularly relevant to study the joint evolution of floral traits. We used in this study the tropical orchid Calanthe sylvatica from Reunion Island. Three distinct colour varieties are observed, presenting lilac, white or purple flowers, and named respectively C. sylvaticavar.lilacina (hereafter referred as var. lilacina), C. sylvaticavar. alba (var. alba) and C. sylvatica var. purpurea (var. purpurea). We investigated the composition of the floral scent produced by these colour varieties using the non-invasive SPME technique in the wild. Scent emissions are dominated by aromatic compounds. Nevertheless, the presence of the terpenoid (E)-4,8-dimethylnona-1,3,7-triene (DMNT) is diagnostic of var. purpurea, with the volatile organic compounds (VOC) produced by some individuals containing up to 60% of DMNT. We evidence specific colour-scent associations in C. sylvatica, with two distinct scent profiles in the three colour varieties: the lilacina-like profile containing no or very little DMNT (<2%) and the purpurea-like profile containing DMNT (>2%). Calanthe sylvatica var. alba individuals group with one or the other scent profile independently of their population of origin. We suggest that white-flowered individuals have evolved at least twice, once from var. lilacina and at least once from var. purpurea after the colonisation of la Reunion. White-flowered individuals may have been favoured by the particular pollinator fauna characterising the island. These flowering varieties of C. sylvatica, which display three colours but two scents profiles prove that colour is not always a good indicator of odour and that colour-scent associations may be complex, depending on pollination ecology of the populations concerned"
Keywords:		Alkenes/metabolism Animals Flowers/physiology *Odorants Orchidaceae/*chemistry Pigmentation/genetics/*physiology Pollination/physiology;
Notes:		"MedlineDelle-Vedove, Roxane Juillet, Nicolas Bessiere, Jean-Marie Grison, Claude Barthes, Nicolas Pailler, Thierry Dormont, Laurent Schatz, Bertrand eng Research Support, Non-U.S. Gov't England 2011/03/08 Phytochemistry. 2011 Jun; 72(8):735-42. doi: 10.1016/j.phytochem.2011.02.005. Epub 2011 Mar 4"