Nitrate transporter NRT1.1 and anion channel SLAH3 form a functional unit to regulate nitrate‐dependent alleviation of ammonium toxicity. Issue 4 (17th April 2022)

• Record Type: Journal Article
• Authors: Xiao, Chengbin; Sun, Doudou; Liu, Beibei; Fang, Xianming; Li, Pengcheng; Jiang, Yao; He, Mingming; Li, Jia; Luan, Sheng; He, Kai
• Is Part Of: Journal of integrative plant biology. Volume 64:Issue 4(2022)
• Page Start: 942
• Page End: 957
• Publication Date: 2022-04-17
• Subjects: ammonium toxicity -- nitrate -- rhizosphere acidification -- NRT1.1 -- SLAH3; Plants -- Periodicals; Plants -- China -- Periodicals; Electronic journals; 580.5
• DOI: 10.1111/jipb.13239
• Languages: English
• ISSNs: 1672-9072

Abstract

Abstract: Ammonium (NH4 + ) and nitrate (NO3 − ) are major inorganic nitrogen (N) sources for plants. When serving as the sole or dominant N supply, NH4 + often causes root inhibition and shoot chlorosis in plants, known as ammonium toxicity. NO3 − usually causes no toxicity and can mitigate ammonium toxicity even at low concentrations, referred to as nitrate‐dependent alleviation of ammonium toxicity. Our previous studies indicated a NO3 − efflux channel SLAH3 is involved in this process. However, whether additional components contribute to NO3 − ‐mediated NH4 + detoxification is unknown. Previously, mutations in NO3 − transporter NRT1.1 were shown to cause enhanced resistance to high concentrations of NH4 + . Whereas, in this study, we found when the high‐NH4 + medium was supplemented with low concentrations of NO3 −, nrt1.1 mutant plants showed hyper‐sensitive phenotype instead. Furthermore, mutation in NRT1.1 caused enhanced medium acidification under high‐NH4 + /low‐NO3 − condition, suggesting NRT1.1 regulates ammonium toxicity by facilitating H + uptake. Moreover, NRT1.1 was shown to interact with SLAH3 to form a transporter‐channel complex. Interestingly, SLAH3 appeared to affect NO3 − influx while NRT1.1 influenced NO3 − efflux, suggesting NRT1.1 and SLAH3 regulate each other at protein and/or gene expression levels. Our study thus revealed NRT1.1 and SLAH3 form a functional unit to regulate nitrate‐dependent alleviation of ammonium toxicity through regulating NO3 − transport and balancing rhizosphere acidification. Abstract : When ammonium is the dominant nitrogen source, the uptake of ammonium by plants often dramatically acidifies the rhizosphere, severely inhibiting plant growth. However, a nitrate transporter‐channel complex mediates nitrate transmembrane cycling and alleviates ammonium toxicity by preventing rhizosphere acidification.