Flower scent of Ceropegia stenantha: electrophysiological activity and synthesis of novel components

Abstract

In specialized pollination systems, floral scents are crucial for flower–pollinator communication, but key volatiles that attract pollinators are unknown for most systems. Deceptive Ceropegia trap flowers are famous for their elaborate mechanisms to trap flies. Recent studies revealed species-specific floral chemistry suggesting highly specialized mimicry strategies. However, volatiles involved in fly attraction were until now identified in C. dolichophylla and C. sandersonii , only. We here present data on C. stenantha for which flower scent and pollinators were recently described, but volatiles involved in flower–fly communication stayed unknown. We performed electrophysiological measurements with scatopsid fly pollinators ( Coboldia fuscipes ) and identified 12 out of 13 biologically active floral components. Among these volatiles some were never described from any organism but C. stenantha . We synthesized these components, tested them on antennae of male and female flies, and confirmed their biological activity. Overall, our data show that half of the volatiles emitted from C. stenantha flowers are perceived by male and female fly pollinators and are potentially important for flower–fly communication in this pollination system. Further studies are needed to clarify the role of the electrophysiologically active components in the life of scatopsid fly pollinators, and to fully understand the pollination strategy of C. stenantha .

Fly Pollination of Kettle Trap Flowers of Riocreuxia torulosa (Ceropegieae-Anisotominae): A Generalized System of Floral Deception

“…It is notoriously difficult to distinguish between food and brood-site deception in plants pollinated by Diptera as they often feed on the same material used for oviposition [ 5 ]. Some flowers combine different deceptive strategies to attract pollinators, as Ceropegia stenantha , a species exclusively pollinated by scatopsid flies that also emits rather widespread floral volatiles but in combination with unusual compounds, which are believed to be sex pheromones of pollinating Scatopsidae [ 21 ]. Most volatiles were found to be electrophysiologically active in both male and female scatopsid pollinators ( Coboldia fuscipes ) [ 21 ].…”

“…Riocreuxia flowers have not been investigated much beyond taxonomical revisions (e.g., [ 11 ] and references therein) or phylogenetic analyses (e.g., [ 6 ]). By contrast, Ceropegia is well studied regarding functional flower morphology [ 12 , 14 ], flower–pollinator relationships [ 3 , 15 , 16 , 17 ], and the chemistry behind pollination [ 18 , 19 , 20 , 21 , 22 ]. In Ceropegia , the flowers are functionally highly specialized for fly-pollination, and most species only interact with taxa from one or two Diptera families [ 16 , 19 ].…”

Pitfall Flower Development and Organ Identity of Ceropegia sandersonii (Apocynaceae-Asclepiadoideae)

“…Ceropegia flowers aroused the interest of naturalists more than a century ago [ 19 , 20 ], but most detailed descriptions of floral structure, functional floral parts and tissues, and their complex interaction with flies to achieve pollination were published by Stefan Vogel [ 18 , 21 , 22 ]. Only recently, studies on chemical ecology of Ceropegia species [ 23 , 24 , 25 , 26 , 27 ] elucidated fascinating chemical mimicry strategies such as kleptomyiophily, i.e., mimicry of injured or dead insects as specific food items of kleptoparasitic flies. Apparently, combined floral chemistry and morphology are the key to pollinator attraction and successful pollination of Ceropegia .…”

“…Apparently, combined floral chemistry and morphology are the key to pollinator attraction and successful pollination of Ceropegia . The chemistry received quite some attention from researchers [ 23 , 24 , 25 , 26 , 27 ] but ontogeny and organ development of Ceropegia pitfall flowers are still not fully understood. The molecular processes controlling floral development have not yet been studied, and genes that are involved in the formation of specific floral organs are unknown.…”

How different is similar – exploring development of Ceropegia sandersonii pitfall flowers to elucidate convergent evolution of floral synorganization

“…The most detailed and passionate descriptions of oral structure, functional oral parts and tissues, and their complex interaction with ies to achieve pollination were published by Vogel (9,10,14,15). Only recently, studies on chemical ecology of Ceropegia species (16)(17)(18)(19)(20) elucidated fascinating chemical mimicry strategies such as kleptomyiophily, i.e. mimicry of injured or dead insects as speci c food items of kleptoparasitic ies.…”