Kinase SnRK1.1 regulates nitrate channel SLAH3 engaged in nitrate-dependent alleviation of ammonium toxicity. Issue 1 (9th February 2021)

• Record Type: Journal Article
• Authors: Sun, Doudou; Fang, Xianming; Xiao, Chengbin; Ma, Zhen; Huang, Xuemei; Su, Jingrong; Li, Jia; Wang, Jiafeng; Wang, Suomin; Luan, Sheng; He, Kai
• Is Part Of: Plant physiology. Volume 186:Issue 1(2021)
• Page Start: 731
• Page End: 749
• Publication Date: 2021-02-09
• Subjects: Plant physiology -- Periodicals; Botany -- Periodicals; Periodicals; Electronic journals; 571.2
• DOI: 10.1093/plphys/kiab057
• Languages: English
• ISSNs: 0032-0889

Abstract

Abstract: Nitrate (NO 3 − ) and ammonium (NH 4 + ) are major inorganic nitrogen (N) supplies for plants, but NH 4 + as the sole or dominant N source causes growth inhibition in many plants, known as ammonium toxicity. Small amounts of NO 3 − can significantly mitigate ammonium toxicity, and the anion channel SLAC1 homolog 3 (SLAH3) is involved in this process, but the mechanistic detail of how SLAH3 regulates nitrate-dependent alleviation of ammonium toxicity is still largely unknown. In this study, we identified SnRK1.1, a central regulator involved in energy homeostasis, and various stress responses, as a SLAH3 interactor in Arabidopsis ( Arabidopsis thaliana ). Our results suggest that SNF1-related protein kinase 1 (SnRK1.1) functions as a negative regulator of SLAH3. Kinase assays indicate SnRK1.1 strongly phosphorylates the C-terminal of SLAH3 at the site S601. Under high-NH 4 + /low-pH condition, phospho-mimetic and phospho-dead mutations in SLAH3 S601 result in barely rescued phenotypes and fully complemented phenotypes in slah3 . Furthermore, SnRK1.1 migrates from cytoplasm to nucleus under high-NH 4 + /low-pH conditions. The translocation of SnRK1.1 from cytosol to nucleus under high-ammonium stress releases the inhibition on SLAH3, which allows SLAH3-mediated NO 3 − efflux leading to alleviation of high-NH 4 + /low-pH stress. Our study reveals that the C-terminal phosphorylation also plays important role in SLAH3 regulation and provides additional insights into nitrate-dependent alleviation of ammonium toxicity in plants. Abstract : Nitrate-dependent alleviation of ammonium toxicity involves negative regulation of a nitrate channel by a kinase.