Tip-localized receptors control pollen tube growth and LURE sensing in Arabidopsis
Tip-localized receptors control pollen tube growth and LURE sensing in Arabidopsis
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DOI：
10.1038/nature17413
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发表时间：
2016-03-10
期刊：
影响因子：
64.8
通讯作者：
Higashiyama, Tetsuya
中科院分区：
文献类型：
--
作者：
Takeuchi, Hidenori;Higashiyama, Tetsuya
对尖端生长细胞的定向控制对于动物和植物适当的组织结构和细胞间的交流至关重要(1，2)。在开花植物的有性繁殖中，雄配子体--花粉管的顶端生长正是由雌性线索引导实现受精的(3)。最近，几种雌性分泌肽被确定为物种特异性引诱剂，直接控制花粉管生长的方向(4-6)。然而，花粉管准确而迅速地对来自自己物种的引导信号做出反应的方法尚不清楚。在这里，我们证明了顶端定位的花粉特异性受体样激酶6(PRK6)具有胞外富含亮氨酸的重复结构域，是在半活体条件下感受拟南芥LURE1吸引肽的重要受体，并且对于雌蕊中的胚珠靶向是重要的。PRK6与花粉表达的ROPGEF(植物鸟嘌呤核苷酸交换因子的Rho)相互作用，通过激活信号开关Rho GTP酶ROP1对花粉管的生长起重要作用(参考文献7，8)。PRK6在近缘种风菜的花粉管中对AtLURE1具有反应性。此外，我们的遗传和生理数据表明，通过ROPGEF的PRK6信号和对AtLURE1的感知是与其他PRK家族受体PRK1、PRK3和PRK8协同完成的。值得注意的是，在花粉管顶端生长重新定向之前，聚焦于顶端的PRK6不对称地向外部AtLURE1源积累。这些结果表明，PRK6是外部AtLURE1引诱剂的关键膜受体，并招募了包括ROP信号蛋白在内的核心尖端生长机制。这项工作提供了对有效的花粉管生长的协调和物种特异性的花粉管吸引在雄性和雌性交流过程中的多个受体。
Directional control of tip-growing cells is essential for proper tissue organization and cell-to-cell communication in animals and plants(1,2). In the sexual reproduction of flowering plants, the tip growth of the male gametophyte, the pollen tube, is precisely guided by female cues to achieve fertilization(3). Several female-secreted peptides have recently been identified as species-specific attractants that directly control the direction of pollen tube growth(4-6). However, the method by which pollen tubes precisely and promptly respond to the guidance signal from their own species is unknown. Here we show that tip-localized pollen-specific receptor-like kinase 6 (PRK6) with an extracellular leucine-rich repeat domain is an essential receptor for sensing of the LURE1 attractant peptide in Arabidopsis thaliana under semi-in-vivo conditions, and is important for ovule targeting in the pistil. PRK6 interacted with pollen-expressed ROPGEFs (Rho of plant guanine nucleotide-exchange factors), which are important for pollen tube growth through activation of the signalling switch Rho GTPase ROP1 (refs 7, 8). PRK6 conferred responsiveness to AtLURE1 in pollen tubes of the related species Capsella rubella. Furthermore, our genetic and physiological data suggest that PRK6 signalling through ROPGEFs and sensing of AtLURE1 are achieved in cooperation with the other PRK family receptors, PRK1, PRK3 and PRK8. Notably, the tip-focused PRK6 accumulated asymmetrically towards an external AtLURE1 source before reorientation of pollen tube tip growth. These results demonstrate that PRK6 acts as a key membrane receptor for external AtLURE1 attractants, and recruits the core tip-growth machinery, including ROP signalling proteins. This work provides insights into the orchestration of efficient pollen tube growth and species-specific pollen tube attraction by multiple receptors during male-female communication.