背景回顾：Precise signalling between pollen tubes and synergid cells in the ovule initiates fertilization in flowering plants. Contact of the pollen tube with the ovule triggers calcium spiking in the synergids that induces pollen tube rupture and sperm release. This process, termed pollen tube reception, entails the action of three synergid-expressed proteins in Arabidopsis: FERONIA (FER), a receptor-like kinase; LORELEI (LRE), a glycosylphosphatidylinositol-anchored protein; and NORTIA (NTA), a transmembrane protein of unknown function.  

提出问题：Genetic analyses have placed these three proteins in the same pathway; however, it remains unknown how they work together to enable synergid–pollen tube communication. 

结果1-FER-LRE共受体的配基RALFs：Here we identify two pollen-tube-derived small peptides that belong to the rapid alkalinization factor (RALF) family as ligands for the FER–LRE co-receptor, which in turn recruits NTA to the plasma membrane. 

结果2-钙离子通道蛋白NTA：NTA functions as a calmodulin-gated calcium channel required for calcium spiking in the synergid. 

结果3-FER-LRE-NTA：We also reconstitute the biochemical pathway in which FER–LRE perceives pollen-tube-derived peptides to activate the NTA calcium channel and initiate calcium spiking, a second messenger for pollen tube reception. 

结论：The FER–LRE–NTA trio therefore forms a previously unanticipated receptor–channel complex in the female cell to recognize male signals and trigger the fertilization process.

 摘 要 

花粉管和胚珠中助细胞之间的精确信号传递起始有花植物的受精。花粉管与胚珠的接触会触发助细胞中的钙离子峰值，从而诱导花粉管爆裂和精子释放。这一过程被称为花粉管接收，涉及到拟南芥中在助细胞中表达的3个蛋白，即类受体激酶FER、糖基磷脂酰肌醇锚定蛋白LRE以及一个功能未知的跨膜蛋白NTA。遗传分析表明这三个蛋白在同一途径发挥作用；然而，这些蛋白是如何协同作用于助细胞–花粉管通信的，目前尚不清楚。本文中，作者鉴定到了两个来源于花粉管的小肽，这两个小肽属于快速碱化因子RALF家族，作为FER–LRE共受体的配体，将NTA招募至质膜。NTA作为钙调蛋白门控钙离子通道，作用于助细胞中的钙离子峰形成。另外，作者还重建了FER-LRE感知源自花粉管的小肽，从而激活NTA钙离子通道，起始花粉管接收的第二信使，即钙离子峰的生化途径。因此，FER–LRE–NTA三个蛋白形成一个先前未知的受体-通道复合体，在雌性细胞中作用于识别雄性信号并触发受精过程。

 Sheng Luan