Abstract
Pollen is required for fertilization and the associated production of seeds and fruits, which are important for human nutrition. Research on the tricellular pollen of Arabidopsis thaliana revealed that chromatin is highly condensed and transcriptional activity is suppressed in sperm cells. However, comprehensive structural investigations involving generative cells of bicellular pollen have not been conducted. In this study, we provide relevant insights into other angiosperms that produce bicellular pollen. Lilium longiflorum, which has large and easily observable nuclei, was used for a detailed analysis of the chromatin structure and transcriptionally active regions in pollen and pollen tubes. Chromatin was condensed, resulting in a ribbon-like structure that was clearly visible in mature generative cell nuclei. Additionally, transcriptionally active regions were restricted to the intersections of chromatin as pollen desiccated. Although de novo transcription was revealed to be unnecessary for pollen tube growth, transcriptional activity temporarily resumed before generative cell division during pollen tube growth. Moreover, the inhibition of de novo transcription influenced changes in nuclear morphology. In this study, the distinctive chromatin structures and transcriptional activity states in generative cell nuclei of bicellular pollen were elucidated, with the generated data contributing to a deeper understanding of transcription and other regulatory mechanisms involved in pollen maturation and pollen tube growth.
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Data supporting the findings of this study are available from the corresponding author upon reasonable request.
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Acknowledgements
We are grateful to the Akita Prefectural Government and the Forestry Agency of Japan for granting permission and the Cultural Property Protection Office of Yuzawa city for providing support for the collection of K. japonica stamen. We also thank Prof. Dr. Jun Yokoyama and Mr. Masaki Sakaki for their assistance in collecting K. japonica stamen. We thank Prof. Dr. Yutaka Miyazawa and Prof. Dr. Yasushi Tamura for sharing equipment. We thank Edanz (https://jp.edanz.com/ac) for editing a draft of this manuscript. This research was supported by MEXT/JSPS KAKENHI (Grant Numbers 20K15836 and 23K14218), JST ACT-X (Grant Number JPMJAX22BB), and Nippon Genetics Co., Ltd.
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All authors contributed to the study conception and design as well as material preparation, data collection, and analysis. Mio K. Shibuta wrote the first draft of the manuscript, which was reviewed and revised by all authors. All authors read and approved the final manuscript.
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Shibuta, M.K., Aso, T. & Okawa, Y. Dynamic changes in chromatin structure and transcriptional activity in the generative cells of Lilium longiflorum. J Plant Res (2025). https://doi.org/10.1007/s10265-025-01637-5
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DOI: https://doi.org/10.1007/s10265-025-01637-5