摘要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 tox-icity. Our previous studies indicated a NO3?efflux channel SLAH3 is involved in this process. How-ever, 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 sup-plemented 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, sug-gesting NRT1.1 and SLAH3 regulate each other at protein and/or gene expression levels. Our study thus revealed NRT1.1 and SLAH3 form a func-tional unit to regulate nitrate-dependent alleviation of ammonium toxicity through regulating NO3?transport and balancing rhizosphere acidification.