Fukushima Kazuki, Hayashi Maki, Watanabe Masao
Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi, 980-8577, Japan.
Plant Reprod. 2025 Jun 6;38(2):15. doi: 10.1007/s00497-025-00525-1.
The stigma papilla cells of Arabidopsis thaliana control water transport to pollen by regulating the morphology of vacuoles in papilla cells after pollination. Pollen hydration is the first crucial response after pollination for successful fertilization. In the Brassicaceae family, papilla cells on the stigma supply water to pollen. In pollinated papilla cells, cellular responses essential for pollen hydration are induced. However, it remains unclear how papilla cells release water from inside the cells to the pollen. Here, we set up a live-cell imaging system for observing vacuole dynamics in Arabidopsis thaliana papilla cells and investigated the role of vacuole morphology in these cells in the regulation of water transfer to pollen. Before pollination, vacuoles in the papilla cells changed their morphology through fusion and constriction; however, after pollination, they formed larger vacuoles and exhibited reduced movement. Additionally, when the morphological variation of vacuoles in the papilla cells was inhibited by wortmannin treatment, the pollen hydration rate decreased in a concentration-dependent manner. In contrast, the vacuoles tended to be less constricted even before pollination and showed less variation than wild-type after pollination in Rho-like GTPase from plants 2 (ROP2) mutant papilla cells, where the pollen hydration rate is faster. We propose that the regulation of vacuole morphology in papilla cells is involved in water transfer to pollen during pollination.
拟南芥柱头乳突细胞通过调节授粉后乳突细胞中液泡的形态来控制水分向花粉的运输。花粉水合作用是授粉后成功受精的第一个关键反应。在十字花科中，柱头上的乳突细胞为花粉提供水分。在授粉的乳突细胞中，会诱导出对花粉水合作用至关重要的细胞反应。然而，目前尚不清楚乳突细胞如何将细胞内的水分释放到花粉中。在此，我们建立了一个活细胞成像系统，用于观察拟南芥乳突细胞中液泡的动态变化，并研究这些细胞中液泡形态在调节水分向花粉转移中的作用。授粉前，乳突细胞中的液泡通过融合和收缩改变其形态；然而，授粉后，它们形成更大的液泡并表现出运动减少。此外，用渥曼青霉素处理抑制乳突细胞中液泡的形态变化时，花粉水合率呈浓度依赖性下降。相反，在花粉水合率较快的植物Rho样GTP酶2（ROP2）突变体乳突细胞中，即使在授粉前液泡也倾向于较少收缩，并且授粉后与野生型相比变化较小。我们提出，乳突细胞中液泡形态的调节参与了授粉过程中水分向花粉的转移。
