Liu Lingtong, Zheng Canhui, Kuang Baijan, Wei Liqin, Yan Longfeng, Wang Tai
Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
University of Chinese Academy of Sciences, Beijing, China.
PLoS Genet. 2016 Jul 22;12(7):e1006085. doi: 10.1371/journal.pgen.1006085. eCollection 2016 Jul.
During sexual reproduction of flowering plants, the pollen tube grows fast and over a long distance within the pistil to deliver two sperms for double fertilization. Growing plant cells need to communicate constantly with external stimuli as well as monitor changes in surface tension of the cell wall and plasma membrane to coordinate these signals and internal growth machinery; however, the underlying mechanisms remain largely unknown. Here we show that the rice member of plant-specific receptor-like kinase CrRLK1Ls subfamily, Ruptured Pollen tube (RUPO), is specifically expressed in rice pollen. RUPO localizes to the apical plasma membrane and vesicle of pollen tubes and is required for male gamete transmission. K+ levels were greater in pollen of homozygous CRISPR-knockout lines than wild-type plants, and pollen tubes burst shortly after germination. We reveal the interaction of RUPO with high-affinity potassium transporters. Phosphorylation of RUPO established and dephosphorylation abolished the interaction. These results have revealed the receptor-like kinase as a regulator of high-affinity potassium transporters via phosphorylation-dependent interaction, and demonstrated a novel receptor-like kinase signaling pathway that mediates K+ homeostasis required for pollen tube growth and integrity.
在开花植物的有性生殖过程中，花粉管在雌蕊内快速且远距离生长，以输送两个精子进行双受精。生长中的植物细胞需要不断与外部刺激进行交流，并监测细胞壁和质膜表面张力的变化，以协调这些信号和内部生长机制；然而，其潜在机制在很大程度上仍不清楚。在这里，我们表明植物特异性类受体激酶CrRLK1Ls亚家族的水稻成员——破裂花粉管（RUPO），在水稻花粉中特异性表达。RUPO定位于花粉管的顶端质膜和囊泡，是雄配子传递所必需的。纯合CRISPR敲除系花粉中的钾离子水平高于野生型植株，且花粉管在萌发后不久就会破裂。我们揭示了RUPO与高亲和力钾转运体的相互作用。RUPO的磷酸化建立了这种相互作用，而去磷酸化则消除了这种相互作用。这些结果揭示了类受体激酶通过磷酸化依赖性相互作用作为高亲和力钾转运体的调节因子，并证明了一种新的类受体激酶信号通路，该通路介导花粉管生长和完整性所需的钾离子稳态。
