Variation In Scent Composition Research Articles

Phylogenetic fragrance patterns in Nicotiana sections Alatae and Suaveolentes

We analyzed floral volatiles from eight tobacco species (Nicotiana; Solanaceae) including newly discovered Brazilian taxa ( Nicotiana mutabilis and “Rastroensis”) in section Alatae. Eighty-four compounds were found, including mono- and sesquiterpenoids, nitrogenous compounds, benzenoid and aliphatic alcohols, aldehydes and esters. Floral scent from recent accessions of Nicotiana alata, Nicotiana bonariensis and Nicotiana langsdorffii differed from previously published data, suggesting intraspecific variation in scent composition at the level of biosynthetic class. Newly discovered taxa in Alatae, like their relatives, emit large amounts of 1,8-cineole and smaller amounts of monoterpenes on a nocturnal rhythm, constituting a chemical synapomorphy for this lineage. Fragrance data from three species of Nicotiana sect. Suaveolentes, the sister group of Alatae, (two Australian species: N. cavicola, N. ingulba; one African species: N. africana), were compared to previously reported data from their close relative, N. suaveolens. Like N. suaveolens, N. cavicola and N. ingulba emit fragrances dominated by benzenoids and phenylpropanoids, whereas the flowers of N. africana lacked a distinct floral scent and instead emitted only small amounts of an aliphatic methyl ester from foliage. Interestingly, this ester also is emitted from foliage of N. longiflora and N. plumbaginifolia (both in section Alatae s.l.), which share a common ancestor with N. africana. This result, combined with the synapomorphic pattern of 1,8 cineole emission in Alatae s.s., suggests that phylogenetic signal explains a major component of fragrance composition among tobacco species in sections Alatae and Suaveolentes. At the intraspecific level, interpopulational scent variation is widespread in sect. Alatae, and may reflect edaphic specialization, introgression, local pollinator shifts, genetic drift or artificial selection in cultivation. Further studies with genetically and geographically well-defined populations are needed to distinguish between these possibilities.

Floral scent and nectar production in Parkia biglobosa Jacq. (Leguminosae: Mimosoideae)

Composition and variation in scent chemistry among individuals and populations, and nocturnal variation in scent composition and nectar production were studied in the African bat-pollinated species Parkia biglobosa. Floral scent was sampled using headspace techniques and chemical composition determined by GC-MS. Nectar production and sugar concentration were measured. The floral scent of P. biglobosa contained mainly benzenoids and isoprenoids. The total amount of volatiles produced and the chemical composition varied within and among the populations studied, as did nectar production. A nocturnal variation in the production of individual compounds and in nectar production was also found, but the sugar concentration of the nectar was fairly constant. Most of the floral scent compounds in P. biglobosa are common in the floral scent of plants pollinated by various groups of animals. The temporal scent and nectar production in P. biglobosa showed highest production early during anthesis and then declined following bat visitation. Published descriptions of floral scents in other species of Parkia imply the presence of sulphur compounds, as has been reported in several bat-pollinated species in the Neotropics. However, Parkia biglobosa did not contain any sulphur compounds, which shows that megabats, in this case, do not use sulphur compounds as foraging cues, as has been suggested for microbats in the New World.

Floral scent and nectar production in Parkia biglobosa Jacq. (Leguminosae: Mimosoideae)

Composition and variation in scent chemistry among individuals and populations, and nocturnal variation in scent composition and nectar production were studied in the African bat-pollinated species Parkia biglobosa. Floral scent was sampled using headspace techniques and chemical composition determined by GC-MS. Nectar production and sugar concentration were measured. The floral scent of P. biglobosa contained mainly benzenoids and isoprenoids. The total amount of volatiles produced and the chemical composition varied within and among the populations studied, as did nectar production. A nocturnal variation in the production of individual compounds and in nectar production was also found, but the sugar concentration of the nectar was fairly constant. Most of the floral scent compounds in P. biglobosa are common in the floral scent of plants pollinated by various groups of animals. The temporal scent and nectar production in P. biglobosa showed highest production early during anthesis and then declined following bat visitation. Published descriptions of floral scents in other species of Parkia imply the presence of sulphur compounds, as has been reported in several bat-pollinated species in the Neotropics. However, Parkia biglobosa did not contain any sulphur compounds, which shows that megabats, in this case, do not use sulphur compounds as foraging cues, as has been suggested for microbats in the New World.

Natural Products of Abdominal and Metathoracic Scent Glands of Coreoid Bugs1, 2

Chemical compositions of metathoracic scents were analyzed for the coreoid bugs Megalotomus quinquespinosus, Alydus eurinus, A. pilosulus, Leptoglossus chypealis, L. oppositus, Archimerus alternatus, Acanthocerus (Euthochtha) galeator , and Merocoris distinctus . Chemical compositions of the corresponding nymphal dorsal abdominal scents were also determined for all species except M. distinctus . Metathoracic scents were in all cases distinct from abdominal scents of the same species. Adult scents were comprised of volatile aliphatic acids, aldehydes, alcohols, and esters, with the composition of metathoracic scents corroborating morphologically microbased taxonomy as low as the generic level, but not at the species level. Abdominal scents consisted of an aqueous phase and an organic phase. The organic phase of abdominal scents was qualitatively uniform, containing trans -2-hexenal and trans -4-oxo-2-hexenal as major constituents, with lesser amounts of derivatives and homologues. Only minor variation occurred between males and females within a species, and between individuals of a species. No significant geographic variation in scent composition was detected. Some data indicated ester and aldehyde components are present at higher concentrations in young bugs than old bugs.