CONICET | Buscador de Institutos y Recursos Humanos

The olfactory components of floral advertisement can be complex, often showingdynamic patterns of emission and chemical composition that may reflect diversefunctions related to pollination. In this study we investigated the spatial and temporalvariation of volatile production in the distinctive kettle trap flowers of the Neotropicalpipevine Aristolochia gigantea (Aristolochiaceae). These flowers show unusualcomplexity in scent chemistry and floral morphology in addition to conspicuous changesin scent at distinct stages during floral ontogeny. In this study, volatiles were collectedfrom separate stages in development (bud, female, male, wilted flower), and fromdifferent functional units (limb, black ring, yellow disk, utricle, nectary) within eachstage. Our results document a strikingly complex and dynamic floral scent compositionfor A. gigantea. Female stage floral emissions are dominated by sweet lemon-scentedcitronella-like compounds including (E)- and (Z)-citral, citronellol and citronellal, and atthe same time include smaller amounts of pungent, brood-site associated volatiles such asdimethyl disulfide, 2-heptanone, and 3-methyl-1-butanol. Volatile emissions plummetone day later in male stage flowers, except for increased production of monoterpenoidsand sesquiterpenoids, including a burst of linalool within the floral chamber. Volatilesemitted from wilted flowers resemble the vegetative background as soon as 48 hours postanthesis. Multidimensional scaling revealed unexpected differentiation of volatileemissions across spatial units of the complex flower (e.g. within vs. outside of the trap),as well as at different stages of sexual expression as flowers matured. These resultssuggest that protogynous kettle trap flowers or inflorescences utilize a chemical divisionof labor, in concert with visual and tactile cues, to choreograph pollinator behavior suchthat female and male floral functions are optimized.