Pre-fertilization hybridization barriers are the main causes of inter-subgeneric hybridization challenges in water lily. However, the mechanism underlying low compatibility between pollen and stigma of water lily remains unclear. This study demonstrates that CBL-interacting protein kinase 6 (CIPK6) responded to the signaling exchange between incompatible pollen and stigma through interactions with SNF1-related kinase 1 (SnRK1) and promotes the accumulation of SnRK1 protein. Activated SnRK1 interacted with 9-cis-epoxycarotenoid dioxygenase 2 (NCED2) to promote its degradation, thereby inhibiting abscisic acid (ABA) synthesis. A decrease in ABA content in the stigma impaired the ABA-mediated removal of reactive oxygen species (ROS), ultimately resulting in the rejection of the incompatible pollen by the stigma. Our results highlight the essential role of the NpCIPK6–NpSnRK1–NpNCED2 module in conferring inter-subgeneric hybridization barriers in water lily by interfering with ABA synthesis and promoting ROS accumulation. This study offers valuable mechanistic insights into cellular signaling and reproductive barriers in water lily as well as across other biological contexts.

中文翻译：

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NpCIPK6–NpSnRK1 模块通过降低脱落酸含量促进睡莲（睡莲）中的亚属间杂交屏障


受精前杂交障碍是睡莲亚属间杂交挑战的主要原因。然而，睡莲花粉与柱头之间低相容性的机制仍不清楚。本研究表明，CBL 相互作用蛋白激酶 6 （CIPK6） 通过与 SNF1 相关激酶 1 （SnRK1） 的相互作用响应不相容花粉和柱头之间的信号交换，并促进 SnRK1 蛋白的积累。激活的 SnRK1 与 9-顺式-环氧类胡萝卜素双加氧酶 2 （NCED2） 相互作用以促进其降解，从而抑制脱落酸 （ABA） 合成。柱头中 ABA 含量的降低损害了 ABA 介导的活性氧 （ROS） 去除，最终导致柱头排斥不相容的花粉。我们的结果强调了 NpCIPK6-NpSnRK1-NpNCED2 模块通过干扰 ABA 合成和促进 ROS 积累，在睡莲中赋予亚属间杂交屏障的重要作用。这项研究为睡莲以及其他生物学背景下的细胞信号传导和生殖屏障提供了有价值的机制见解。