Shibuta Mio K, Aso Tsugumi, Okawa Yutsuki
Academic Assembly (Faculty of Science), Yamagata University, 1-4-12 Kojirakawa, Yamagata-City, Yamagata, 990-8560, Japan.
Faculty of Science, Yamagata University, 1-4-12 Kojirakawa, Yamagata-City, Yamagata, 990-8560, Japan.
J Plant Res. 2025 Apr 15. doi: 10.1007/s10265-025-01637-5.
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.
受精以及随之而来的种子和果实的产生都需要花粉，而种子和果实对人类营养至关重要。对拟南芥三细胞花粉的研究表明，精子细胞中的染色质高度浓缩，转录活性受到抑制。然而，尚未对二细胞花粉的生殖细胞进行全面的结构研究。在本研究中，我们为其他产生二细胞花粉的被子植物提供了相关见解。由于麝香百合具有大且易于观察的细胞核，因此被用于详细分析花粉和花粉管中的染色质结构和转录活性区域。染色质发生浓缩，在成熟生殖细胞核中形成清晰可见的带状结构。此外，随着花粉干燥，转录活性区域局限于染色质的交叉点。虽然已发现从头转录对于花粉管生长并非必需，但在花粉管生长过程中，转录活性在生殖细胞分裂前暂时恢复。此外，对从头转录的抑制影响了核形态的变化。在本研究中，阐明了二细胞花粉生殖细胞核中独特的染色质结构和转录活性状态，所生成的数据有助于更深入地理解花粉成熟和花粉管生长过程中涉及的转录及其他调控机制。
