A nitrogen-responsive cytokinin oxidase/dehydrogenase regulates root response to high ammonium in rice

文献类型： 外文期刊

第一作者： Li, Lun

作者： Li, Lun;Jia, Letian;Duan, Xingliang;Ye, Chengyu;Zhang, Yuwen;Luo, Le;Xuan, Wei;Li, Lun;Jia, Letian;Duan, Xingliang;Ye, Chengyu;Zhang, Yuwen;Luo, Le;Xuan, Wei;Lv, Yuanda;Qi, Weicong;Lv, Yuanda;Qi, Weicong;Ding, Chengqiang;Ding, Chengqiang;Ding, Chengqiang;Motte, Hans;Beeckman, Tom;Motte, Hans;Beeckman, Tom

作者机构：

关键词： ammonium; auxin; CKX; cytokinin; lateral root; rice; seminal root

期刊名称：NEW PHYTOLOGIST （ 影响因子：8.1； 五年影响因子：10.3 ）

ISSN： 0028-646X

年卷期： 2024 年 244 卷 4 期

页码：

收录情况： SCI

摘要： Plant root system is significantly influenced by high soil levels of ammonium nitrogen, leading to reduced root elongation and enhanced lateral root branching. In Arabidopsis, these processes have been reported to be mediated by phytohormones and their downstream signaling pathways, while the controlling mechanisms remain elusive in crops. Through a transcriptome analysis of roots subjected to high/low ammonium treatments, we identified a cytokinin oxidase/dehydrogenase encoding gene, CKX3, whose expression is induced by high ammonium. Knocking out CKX3 and its homologue CKX8 results in shorter seminal roots, fewer lateral roots, and reduced sensitivity to high ammonium. Endogenous cytokinin levels are elevated by high ammonium or in ckx3 mutants. Cytokinin application results in shorter seminal roots and fewer lateral roots in wild-type, mimicking the root responses of ckx3 mutants to high ammonium. Furthermore, CKX3 is transcriptionally activated by type-B RR25 and RR26, and ckx3 mutants have reduced auxin content and signaling in roots under low ammonium. This study identified RR25/26-CKX3-cytokinin as a signal module that mediates root responses to external ammonium by modulating of auxin signaling in the root meristem and lateral root primordium. This highlights the critical role of cytokinin metabolism in regulating rice root development in response to ammonium.

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