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Floral scent chemistry within the genus Linnaea (Caprifoliaceae)

Bergström, L. Gunnar W., Bergquist, Sara, Stenhagen, Gunnar, Gahmberg, Carl G., Maia, Artur Campos D., Nordenstam, Bertil
Nordic journal of botany 2018 v.36 no.3 pp. enjb-01732
Caprifoliaceae, attractants, benzaldehyde, benzene, beta-pinene, botanists, circadian rhythm, common names, flowers, gardeners, gas chromatography-mass spectrometry, headspace analysis, insects, odors, phenylethyl alcohol, phenylpropanoids, pollination, sesquiterpenoids
‘Beauty bush’ and ‘twin flower’ are common names attributed to two well‐recognizable species belonging to the genus Linnaea (16 spp.) – L. amabilis and L. borealis – long admired by botanists and gardeners for their perfumed paired bell‐shaped flowers. In the present study, we investigated their floral scent compositions through gas chromatography – mass spectrometry (GC‐MS) analysis of dynamic headspace samples. Because the flowers of L. borealis in wild populations are fragrant both during the day and in the evening, circadian variation of scent emission was also assessed for this species. In total, 26 chemical compounds comprise the floral scent bouquets of L. amabilis and L. borealis, identified as monoterpenes (14), benzenoids and phenylpropanoids (5), aliphatics (3), sesquiterpenes (3) and irregular terpenes (1). Whereas monoterpenes, notably (‐)‐α‐ and β‐pinene, dominated the scent of L. amabilis (over 82% relative abundance), benzene derivates: 1,4 dimethoxybenzene, anisaldehyde, 2‐phenylethanol, benzaldehyde and nicotinaldehyde were exclusive to analysed headspace samples of L. borealis, accounting for 52% to 100% of their relative compositions, in three Swedish populations. A southwestern Finnish population was characterized by the four first mentioned benzenoid compounds and large amounts of (‐)‐α‐ and β‐pinenes plus two aliphatic substances. The scent compounds identified for both species are ubiquitous and may serve as generalist attractants/stimulants for a broad assortment of anthophilous insects. The basic work on the flower scent of L. amabilis and L. borealis should inspire studies of their pollination biology, primarily the behaviour‐guiding roles of the characteristic emitted volatiles.