Disruption of the pollen-expressed FERONIA homologs ANXUR1 and ANXUR2 triggers pollen tube discharge
Disruption of the pollen-expressed FERONIA homologs ANXUR1 and ANXUR2 triggers pollen tube discharge
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DOI：
10.1242/dev.040071
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发表时间：
2009-10-01
期刊：
影响因子：
4.6
通讯作者：
Grossniklaus, Ueli
中科院分区：
文献类型：
--
作者：
Boisson-Dernier, Aurelien;Roy, Sucharita;Grossniklaus, Ueli
在真核生物的繁殖过程中，雄性配子到雌性配子的精确传递需要复杂的信号交换和雄性和雌性组织之间的完美沟通。在被子植物中，最近发现的分子机制对于成功传递精子所需的雄性（花粉管）和雌性配子体之间的对话至关重要。当花粉管到达雌配子体时，它们停止生长，破裂并排出精细胞。这些过程由雌配子体通过受体样丝氨酸-苏氨酸激酶（RLK）FERONIA（FER）控制。然而，控制精子输送的雄性信号成分仍然难以捉摸。在这里，我们表明，ANXUR 1和ANXUR 2（ANX 1，ANX 2），其中编码的FER-RLK在拟南芥中最接近的同源物，优先在花粉中表达。此外，ANX 1-YFP和ANX 2-YFP融合蛋白显示极性定位于花粉管顶端的质膜。最后，遗传分析表明，ANX 1和ANX 2功能冗余控制的时间，花粉管放电anx 1 anx 2双突变体的花粉管停止其生长和爆裂在体外，并未能达到雌配子体在体内。我们建议ANX-RLKs组成型抑制花粉管破裂和精子排出在生长的花粉管尖端，以维持其在母体组织内的生长，直到它们到达雌配子体。到达后，雌性FER依赖性信号级联被激活以介导花粉管接收和受精，而雄性ANX依赖性信号被灭活，使花粉管破裂并输送其精子细胞以实现受精。
The precise delivery of male to female gametes during reproduction in eukaryotes requires complex signal exchanges and a flawless communication between male and female tissues. In angiosperms, molecular mechanisms have recently been revealed that are crucial for the dialog between male (pollen tube) and female gametophytes required for successful sperm delivery. When pollen tubes reach the female gametophyte, they arrest growth, burst and discharge their sperm cells. These processes are under the control of the female gametophyte via the receptor-like serine-threonine kinase (RLK) FERONIA (FER). However, the male signaling components that control the sperm delivery remain elusive. Here, we show that ANXUR1 and ANXUR2 (ANX1, ANX2), which encode the closest homologs of the FER-RLK in Arabidopsis, are preferentially expressed in pollen. Moreover, ANX1-YFP and ANX2-YFP fusion proteins display polar localization to the plasma membrane at the tip of the pollen tube. Finally, genetic analyses demonstrate that ANX1 and ANX2 function redundantly to control the timing of pollen tube discharge as anx1 anx2 double-mutant pollen tubes cease their growth and burst in vitro and fail to reach the female gametophytes in vivo. We propose that ANX-RLKs constitutively inhibit pollen tube rupture and sperm discharge at the tip of growing pollen tubes to sustain their growth within maternal tissues until they reach the female gametophytes. Upon arrival, the female FER-dependent signaling cascade is activated to mediate pollen tube reception and fertilization, while male ANX-dependent signaling is deactivated, enabling the pollen tube to rupture and deliver its sperm cells to effect fertilization.