New Phytologist / The betrayed thief the extraordinary strategy of Aristolochia rotunda to deceive its pollinators

Pollination of several angiosperms is based on deceit. In such systems, the flowers advertise a reward that ultimately is not provided. We report on a previously unknown pollination/mimicry system discovered in deceptive Aristolochia rotunda (Aristolochiaceae). Pollinators were collected in the natural habitat and identified. Flower scent and the volatiles of insects (models) potentially mimicked were analyzed by chemical analytical techniques. Electrophysiological and behavioral tests on the pollinators identified the components that mediate the plantpollinator interaction and revealed the model of the mimicry system. The main pollinators of A. rotunda were female Chloropidae. They are food thieves that feed on secretions of true bugs (Miridae) while these are eaten by arthropod predators. Freshly killed mirids and Aristolochia flowers released the same scent components that chloropids use to find their food sources. Aristolochia exploits these components to deceive their chloropid pollinators. Aristolochia and other trap flowers were believed to lure saprophilous flies and mimic brood sites of pollinators. We demonstrate for A. rotunda, and hypothesize for other deceptive angiosperms, the evolution of a different, kleptomyiophilous pollination strategy. It involves scent mimicry and the exploitation of kleptoparasitic flies as pollinators. Our findings suggest a reconsideration of plants assumed to show sapromyiophilous pollination.(VLID)221519

Flowers of Deceptive Aristolochia microstoma Are Pollinated by Phorid Flies and Emit Volatiles Known From Invertebrate Carrion

Deceptive flowers decoy pollinators by advertising a reward, which finally is not provided. Numerous deceptive plants are pollinated by Diptera, but the attractive cues and deceptive strategies are only identified in a few cases. A typical fly-deceptive plant genus is Aristolochia, which evolved sophisticated trap flowers to temporarily capture pollinators. Though rarely demonstrated by experimental approaches, Aristolochia species are believed to chemically mimic brood sites, food sources for adult flies, or utilize sexual deception. Indeed, for most species, studies on scent composition and attractive signals are lacking. In this study, we focused on Aristolochia microstoma, a peculiar Greek endemic with flowers that are presented at ground level in the leaf litter or between rocks and are characterized by a unique morphology. We analyzed flower visitor and pollinator spectra and identified the floral scent composition using dynamic headspace and gas chromatography coupled to mass spectrometry (GC/MS). Female and male phorid flies (Phoridae) are the exclusive pollinators, although the flowers are also frequently visited by Sciaridae, as well as typical ground-dwelling arthropods, such as Collembola and arachnids. The carrion-like floral scent mainly consists of the oligosulphide dimethyldisulfide and the nitrogen-bearing compound 2,5-dimethylpyrazine. These compounds together are known to be released from decomposing insects, and thus, we conclude that pollinators are likely deceived by chemical imitation of invertebrate carrion, a deceptive strategy not described from another plant species so far.</jats:p

New Phytologist / The betrayed thief the extraordinary strategy of Aristolochia rotunda to deceive its pollinators

Pollination of several angiosperms is based on deceit. In such systems, the flowers advertise a reward that ultimately is not provided. We report on a previously unknown pollination/mimicry system discovered in deceptive Aristolochia rotunda (Aristolochiaceae). Pollinators were collected in the natural habitat and identified. Flower scent and the volatiles of insects (models) potentially mimicked were analyzed by chemical analytical techniques. Electrophysiological and behavioral tests on the pollinators identified the components that mediate the plantpollinator interaction and revealed the model of the mimicry system. The main pollinators of A. rotunda were female Chloropidae. They are food thieves that feed on secretions of true bugs (Miridae) while these are eaten by arthropod predators. Freshly killed mirids and Aristolochia flowers released the same scent components that chloropids use to find their food sources. Aristolochia exploits these components to deceive their chloropid pollinators. Aristolochia and other trap flowers were believed to lure saprophilous flies and mimic brood sites of pollinators. We demonstrate for A. rotunda, and hypothesize for other deceptive angiosperms, the evolution of a different, kleptomyiophilous pollination strategy. It involves scent mimicry and the exploitation of kleptoparasitic flies as pollinators. Our findings suggest a reconsideration of plants assumed to show sapromyiophilous pollination.(VLID)221519

Peruvian Window-Leaved Peperomia Taxa Display Unique Crystal Macropatterns in High-Altitude Environments

Premise of research. Window-leaved Peperomia taxa (WPs) occur in the Peruvian Andes from near sea level to high altitudes and display curled leaves that are generally exposed to high irradiance and periodic drought, far different from the typically uncurled humid-forest, often-shaded Peperomia taxa. Even though representatives of the latter taxa, as well as other members of the Piperales, have been observed for the presence (type) and location (macropattern) of leaf crystals in previous studies, this special group of WP taxa has missed scrutiny. It was important to determine whether the WP taxa contained the same types of crystals in the same tissue locations and, if not, what any differences could be that are related to their anatomy, environment, and physiology. Methodology. Living leaves of 35 available accessions from the 42 currently recognized taxa of WPs were chemically fixed, some cleared and/or vibratome sectioned or fractured to observe the internal leaf tissues for the presence of crystals composed of calcium oxalate with polarizing microscopy and SEM. Pivotal results. WPs variably displayed three types of crystals, i.e., druses, prisms, and crystal sand, in the three major leaf tissues (multiple epidermis/hydrenchyma and palisade and spongy parenchymas). The WPs are distinctly different from uncurled humid-forest, often-shaded Peperomia taxa by often having prisms and crystal sand in their hydrenchyma and consistently having crystal sand in their spongy parenchyma. These results are additional synapomorphies for WPs belonging to the distinct subgenus Fenestratae within the genus Peperomia. Conclusions. The partial or complete enclosing of the hydrenchyma by leaf curling and the resulting increased exposure of the abaxial leaf surface, with the subtending spongy parenchyma containing primarily crystal sand, suggests that these adaptations may provide protection for the primary internal photosynthetic tissue (palisade parenchyma) against photoinhibition by filtering and dispersing the solar irradiance and moderating the internal leaf temperature, two critical conditions allowing these taxa to live in extreme environments.This article is published as Horner, Harry T., Stefan Wanke, Birgit Oelschlägel, and Marie-Stéphanie Samain. "Peruvian Window-Leaved Peperomia Taxa Display Unique Crystal Macropatterns in High-Altitude Environments." International Journal of Plant Sciences 178, no. 2 (2017): 157-167. doi: 10.1086/689281. Posted with permission.</p