Abstract
The suspensor plays an active role during the early embryo development of flowering plants. In orchids, the suspensor cells are highly vacuolated without structural specializations, and the possible mechanism(s) that enable the suspensor to serve as the nutrient uptake site is virtually unknown. Here, we used the fluorescent tracer CFDA to characterize the pathway for symplastic transport in the suspensor cells of developing embryos and to provide direct visual evidence that the orchid suspensor has unique physiological properties. The embryo proper uptakes the fluorescent dye through the suspensor. CF could first be detected throughout the suspensor cell and then subsequently in the embryo proper. A plasmolysis experiment clearly indicates that suspensor cells have a more negative osmotic potential than the adjoining testa cells. It is proposed that the preferential entry of CFDA into the suspensor cell of the Nun orchid is aided by the more negative osmotic potential of the suspensor than neighboring cells, providing a driving force for the uptake of water from the apoplast into the symplast.
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Acknowledgments
We would like to thank Dr Mei-Chu Chung and Miss Mei-Jane Fang (IPMB, Academia Sinica, Taipei, Taiwan) for the use of confocal laser-scanning microscope and technical advice. This work was supported by grants from National Museum of Natural Science, Taiwan to Yung-I Lee and from the Natural Sciences and Engineering Research Council of Canada to Edward C. Yeung.
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Communicated by Scott Russell.
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Lee, YI., Yeung, E.C. The osmotic property and fluorescent tracer movement of developing orchid embryos of Phaius tankervilliae (Aiton) Bl. Sex Plant Reprod 23, 337–341 (2010). https://doi.org/10.1007/s00497-010-0143-y
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DOI: https://doi.org/10.1007/s00497-010-0143-y