NpCIPK6-NpSnRK1 module facilitates intersubgeneric hybridization barriers in water lily (Nymphaea) by reducing abscisic acid content

Abstract

Prefertilization hybridization barriers are the main causes of intersubgeneric 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 intersubgeneric 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.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (grant nos. U1803104 and U2003113), Hainan Natural Science Foundation (grant no. 2021JJLH0031), and Guangxi Natural Science Foundation (grant no. 2022GXNSFBA035635). We would like to thank A&L Scientific Editing (www.alpublish.com) for its linguistic assistance during the preparation of this manuscript.

Author contributions

P.Z. and Y.C.X. conceived the original idea and designed the experiments. P.Z., J.W.L., H.Y.J., Z.J.Y., and H.Y.W. performed the experiments. Y.J.W. provided the experimental materials. P.Z. analyzed the data and wrote the manuscript. C.Q.S., Q.S., and Q.J.J. revised the manuscript. All authors have read and approved the final manuscript.

Data availability

All data needed to support the conclusions of this study are included in the paper and supplementary materials or are available at the request of the corresponding authors.

Conflict of interest statement

The authors declare that they have no conflicts of interest.

Supplementary Data

Supplementary data is available at Horticulture Research online.

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