Ammonium mitigates cadmium toxicity by activating the bZIP20-APX2/CATA transcriptional module in rice seedlings in an ABA-dependent manner

• Published in: Journal of hazardous materials Vol. 480; p. 135874
• Main Authors: Di, Dong-Wei, Li, Ting-Ting, Yu, Zheng-Lun, Cheng, Jie, Wang, Meng, Liu, Chuan-Fa, Wang, Yuan, Kronzucker, Herbert J., Yu, Min, Shi, Weiming
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 05.12.2024
• Subjects: ABA; Ammonium; Antioxidant activity; Cadmium toxicity; OsbZIP20; OsSAPK9; ABA; Ammonium; OsbZIP20; OsSAPK9; Antioxidant activity; Cadmium toxicity
• ISSN: 0304-3894; 1873-3336; 1873-3336
• DOI: 10.1016/j.jhazmat.2024.135874

The amelioration of cadmium (Cd2+) toxicity in plants by ammonium (NH4+) has been widely investigated. However, the molecular mechanisms underpinning this amelioration have remained ambiguous. Here, we found that NH4+ significantly reduces Cd2+ accumulation and enhances antioxidant capacity by increasing ABA accumulation, which, in turn, improves Cd2+ tolerance in rice seedlings. A combination of qPCR, yeast-one-hybrid and dual-luciferase assays, and CUT&RUN-qPCR methods demonstrates that OsbZIP20 directly binds to the promoters of OsAPX2 and OsCATA, activating their transcription, and we show that the process requires phosphorylation modification of OsbZIP20 by OsSAPK9. Under Cd2+ stress, Osbzip20 and Ossapk9 mutants show reduced peroxidase and catalase activities, higher H2O2 accumulation, and reduced Cd2+ tolerance. In sum, our results elucidate a novel mechanism by which NH4+ enhances Cd2+ resistance, through ABA-SAPK9-bZIP20-APX2/CATA, offering a new strategy for improving Cd2+ resistance in rice. [Display omitted] •NH4+ promotes ABA accumulation under Cd stress.•ABA enhances Cd resistance by inhibiting Cd accumulation and maintaining APX and CAT activities.•OsSAPK9 phosphorylates the Ser6 and Ser150 sites of OsbZIP20.•Phosphorylated OsbZIP20 is required for activation of OsAPX2 and OsCATA under Cd stress.