Abstract
Flowering plants attract pollinators via various stimuli such as odor, color, and shape. Factors determining the foraging behavior of pollinators remain a major theme in ecological and evolutionary research, although the floral traits and cognitive ability of pollinators have been investigated for centuries. Here we show that the autofluorescence emitted from pollen and anthers under UV irradiation may act as another attractant for flower-visiting insects. We have identified fluorescent compounds from pollen and anthers of five plant species as hydroxycinnamoyl derivatives. The fluorescent compounds are also shown to quench UV energy and exhibit antioxidant activity, indicating a function as protectants of pollen genes from UV-induced damage. A two-choice assay using honeybees in the field demonstrated that they perceived the blue fluorescence emitted from the fluorescent compounds and were attracted to it. This result suggested that the fluorescence from pollen and anthers serves as a visual cue to attract pollinators under sunlight.
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Acknowledgements
We thank Mr. M. Kaneko (Nagano Vegetable and Ornamental Crops Experiment Station) for providing flowers of P. persica. We wish to acknowledge Assistant Professor M. Murai and Mr. K. Nishino, and Assistant Professor T. Suzuki (Graduate School of Agriculture, Kyoto University) for the mass spectral measurements and the UV/Vis measurements, respectively. For the two-photon excitation microscopy, we thank Ms. K. Takakura at the Fluorescent Live Imaging Core Facility of the Medical Research Support Center, Graduate School of Medicine, Kyoto University, which was supported by Platform for Drug Discovery, Informatics, and Structural Life Science from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We also wish to thank Ms. K. Okamoto-Furuta and Mr. H. Kohda (Center for Anatomical, Pathological and Forensic Medical Researches, Graduate School of Medicine, Kyoto University) for their technical assistance with electron microscopy. Advice and comments given by Associate Professor T. Miyake (Graduate School of Agriculture, Kyoto University) were a great help in the statistical analysis. We are deeply grateful to Professor K. Arikawa (School of Advanced Sciences, Graduate University for Advanced Studies) and Professor Emeritus M. Sasaki (Tamagawa University) for valuable discussion on the behavioral experiments with honeybees. We would like to express our sincere gratitude to Ms. Y. Fukui for warm encouragement.
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Hiroshi Fukui and Katsumi Goto died before publication of this work was completed.
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Mori, S., Fukui, H., Oishi, M. et al. Biocommunication between Plants and Pollinating Insects through Fluorescence of Pollen and Anthers. J Chem Ecol 44, 591–600 (2018). https://doi.org/10.1007/s10886-018-0958-9
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DOI: https://doi.org/10.1007/s10886-018-0958-9