Sugi Naoya, Izumi Rie, Tomomi Shun, Susaki Daichi, Kinoshita Tetsu, Maruyama Daisuke
Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan.
Front Plant Sci. 2023 Jan 26;14:1116289. doi: 10.3389/fpls.2023.1116289. eCollection 2023.
In pollen and pollen tubes, immotile sperm cells are enclosed by an inner vegetative plasma membrane (IVPM), a single endomembrane originating from the vegetative-cell plasma membrane. It is widely believed that sperm cells must be removed from the IVPM prior to gamete associations and fusions; however, details of the timing and morphological changes upon IVPM dissociation remain elusive. Here, we report a rapid IVPM breakdown immediately before double fertilization in . The IVPM was stably observed in coiling pollen tubes when pollen tube discharge was prevented using mutant ovules. In contrast, a semi- fertilization assay in wild-type ovules demonstrated fragmented IVPM around sperm nuclei 1 min after pollen tube discharge. These observations revealed the dynamic alteration of released sperm cells and provided new insights into double fertilization in flowering plants. With a summary of recent findings on IVPM lipid composition, we discussed the possible physiological signals controlling IVPM breakdown.
在花粉和花粉管中，不能运动的精细胞被一层内部营养质膜（IVPM）包裹，这是一层源自营养细胞质膜的单层内膜。人们普遍认为，在配子结合和融合之前，精细胞必须从IVPM上脱离；然而，IVPM解离时的时间细节和形态变化仍不清楚。在这里，我们报告了在[具体植物名称]双受精前IVPM的快速分解。当使用突变胚珠阻止花粉管释放时，在盘绕的花粉管中可稳定观察到IVPM。相比之下，在野生型胚珠中进行的半受精试验表明，花粉管释放后1分钟，精子核周围的IVPM出现碎片化。这些观察结果揭示了释放的精细胞的动态变化，并为开花植物的双受精提供了新的见解。通过总结近期关于IVPM脂质组成的研究结果，我们讨论了控制IVPM分解的可能生理信号。
