Wang Yin-Zheng, Lin Yan-Xiang, Liu Qi, Liu Jing, Barrett Spencer C H
State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
China National Botanical Garden, Beijing 100093, China.
Natl Sci Rev. 2023 Aug 10;10(9):nwad208. doi: 10.1093/nsr/nwad208. eCollection 2023 Sep.
Many plants employ osmotic and hydrostatic pressure to generate movement for survival, but little is known about the cellular mechanisms involved. Here, we report a new cell type in angiosperms termed 'contractile cells' in the stigmas of the flowering plant with a much-expanded rough endoplasmic reticulum (RER). Cryo-scanning electron microscopy and transmission electron microscopy analyses revealed that the RER is continuously distributed throughout the entirety of cells, confirmed by endoplasmic reticulum (ER)-specific fluorescent labeling, and is distinct from the common feature of plant ER. The RER is water-sensitive and extremely elongated with water absorption. We show that the contractile cells drive circadian stigma closing-bending movements in response to day-to-night moisture changes. RNA-seq analyses demonstrated that contractile cells have distinct molecular components. Furthermore, multiple microstructural changes in stigma movements convert an anti-selfing structure into a device promoting selfing-a unique cellular mechanism of reproductive adaptation for uncertain pollination environments.
许多植物利用渗透压和流体静压力来产生生存所需的运动，但对于其中涉及的细胞机制却知之甚少。在此，我们报道了被子植物中一种新的细胞类型，称为“收缩细胞”，存在于开花植物的柱头中，其粗面内质网（RER）大量扩张。冷冻扫描电子显微镜和透射电子显微镜分析表明，粗面内质网在整个细胞中连续分布，经内质网（ER）特异性荧光标记证实，且不同于植物内质网的常见特征。粗面内质网对水敏感，吸水时会极度伸长。我们发现收缩细胞会响应昼夜湿度变化驱动柱头的昼夜闭合弯曲运动。RNA测序分析表明收缩细胞具有独特的分子成分。此外，柱头运动中的多种微观结构变化将一种防止自花授粉的结构转变为促进自花授粉的装置——这是一种针对不确定授粉环境的独特生殖适应细胞机制。
