Yan Yu, Dai Liufeng, Wang Baojie, Wang Ting, Sun Zhenping, Wang Yunzi, Xing Chengcheng, Zhou Jing, Luo Xiaoyan, Zhu Yu, McFarlane Heather E, Gong Yu, Zhang Xiaoxia, Xu Bo, Hu Yuping, Ren Haiyun, Zhang Yi
Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing, China.
Guangdong Institute of Intelligence Science and Technology, Hengqin, Zhuhai, China.
Nat Plants. 2025 Aug 4. doi: 10.1038/s41477-025-02064-z.
Flowering plants rely on double fertilization for their sexual reproduction. A pair of immotile sperm cells (SCs) are conveyed through a pollen tube into the female gametophyte, where they fertilize the egg cell and central cell to give rise to the embryo and endosperm in seeds, respectively. The SCs and the pollen vegetative nucleus (VN) move as a male germ unit (MGU) in pollen tubes. The tryptophan-proline-proline (WPP) domain-interacting tail-anchored proteins (WITs) and WPP domain-interacting proteins (WIPs) are involved in VN migration, and the cytoskeleton is required for MGU transportation in pollen tubes. Here we report that two kinesins, referred to as HUG1 and HUG2, localize at the VN envelope in a WIT- and WIP-dependent manner and surround the SCs in pollen. Mutation of HUG1 and HUG2 leads to disconnected VN and SCs, impaired MGU transportation and reduced plant fertility, supporting key roles of HUG proteins in MGU formation and transportation in pollen.
开花植物依靠双受精进行有性生殖。一对不能游动的精细胞（SCs）通过花粉管被输送到雌配子体中，在那里它们分别使卵细胞和中央细胞受精，从而在种子中产生胚和胚乳。精细胞和花粉营养核（VN）在花粉管中作为一个雄配子体单位（MGU）移动。色氨酸 - 脯氨酸 - 脯氨酸（WPP）结构域相互作用的尾锚定蛋白（WITs）和WPP结构域相互作用蛋白（WIPs）参与营养核迁移，并且细胞骨架是花粉管中雄配子体单位运输所必需的。在此我们报道，两种驱动蛋白，称为HUG1和HUG2，以依赖于WIT和WIP的方式定位于营养核包膜，并在花粉中包围精细胞。HUG1和HUG2的突变导致营养核和精细胞分离，雄配子体单位运输受损以及植物育性降低，这支持了HUG蛋白在花粉中雄配子体单位形成和运输中的关键作用。
