Flower color–flower scent associations in polymorphic Hesperis matronalis (Brassicaceae)

• Published in: Phytochemistry (Oxford) Vol. 68; no. 6; pp. 865 - 874
• Main Authors: Majetic, Cassie J., Raguso, Robert A., Tonsor, Stephen J., Ashman, Tia-Lynn
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.03.2007; Elsevier
• Subjects: Analysis of Variance; aromatic compounds; Aromatics; Biological and medical sciences; Brassicaceae; Brassicaceae - metabolism; Brassicaceae - physiology; Cereal and baking product industries; chemical constituents of plants; Chemical constitution; color; diurnal variation; Flower color polymorphism; flowers; Flowers - metabolism; Flowers - physiology; Food industries; Fundamental and applied biological sciences. Psychology; Gas Chromatography-Mass Spectrometry; GC–MS; Hesperis matronalis; Odorants; odors; Pigmentation - physiology; plant biochemistry; plant ecology; plant morphology; Plant physiology and development; plant-insect relations; pollinating insects; polymorphism; Principal Component Analysis; Terpenes - chemistry; Terpenes - metabolism; Terpenoids; volatile organic compounds; Aromatics; Hesperis matronalis; GC–MS; Brassicaceae; Terpenoids; Flower color polymorphism; Volatile compound; Terpenoid; Flower; Color; Emission; Pollination; GC-MS; Pollinator; Cruciferae; Dicotyledones; Angiospermae; Collection; Genetics; Spermatophyta; Chemical composition; Principal component analysis; Polymorphism
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2006.12.009

Principal component analysis of floral volatile compounds from Hesperis matronalis L. resulted in two significant principal components: overall volatile emission rate (PC 1) and chemical composition (PC 2) as determined by terpenoid (negative values) or aromatic (positive values) content. Floral scent emission rate and composition of purple and white flower color morphs of Hesperis matronalis (Brassicaceae) were determined for two populations and, for each, at two times of day using dynamic headspace collection and GC–MS. The floral volatile compounds identified for this species fell into two main categories, terpenoids and aromatics. Principal component analysis of 30 compounds demonstrated that both color morphs emitted more scent at dusk than at dawn. Color morphs varied in chemical composition of scent, but this differed between populations. The white morphs exhibited significant differences between populations, while the purple morphs did not. In the white morphs, one population contains color–scent associations that match expectations from classical pollination syndrome theory, where the flowers have aromatic scents, which are expected to maximize night-flying moth pollinator attraction; in the second population, white morphs were strongly associated with terpenoid compounds. The potential impact that pollinators, conserved biosynthetic pathways, and the genetics of small colonizing populations may have in determining population-specific associations between floral color and floral scent are discussed.