Abstract
In cycads, spermatozoids are released from pollen tubes and swim in fluid toward the archegonia. The source of this fluid was examined using Cycas revoluta Thunb. ovules placed in culture. Dissected female gametophytes just before fertilization produced copious fluid on their upper surface. The fluid first appeared around the archegonial chamber and then on the inside of the archegonial chamber. When this fluid was applied to dry turgid pollen tubes, they discharged spermatozoids 12 h later. The archegonial neck appeared as two semi-spherical swellings, whereas the four neck cells later became visible and they separated in a schizogenous manner. Many globose particles appear on the top of the archegonial neck cells when the fluid is present. The contents of pollen tubes, spermatozoids and surrounding liquid intermingle with the secreted fluid. The female gametophyte differs in ultrastructure during the stages before and after fluid secretion, the latter showing changes suggestive of fluid secretion from the female gametophyte.
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Acknowledgments
This study was initially supported by a grant from Ministry of Education, Culture, Sports, Science and Technology, Japan, and subsequently conducted as a part of the research project “Interactions between natural environment and human social systems in subtropical islands” supported by the Research Institute for Humanity and Nature, Japan. The authors would like to thank the anonymous reviewers and editor for their valuable comments and suggestions to improve the manuscript.
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Communicated by Scott Russell.
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Takaso, T., Kimoto, Y., Owens, J.N. et al. Secretions from the female gametophyte and their role in spermatozoid induction in Cycas revoluta . Plant Reprod 26, 17–23 (2013). https://doi.org/10.1007/s00497-012-0204-5
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DOI: https://doi.org/10.1007/s00497-012-0204-5