Effect of NaCl on ammonium and nitrate uptake and transport in salt-tolerant and salt-sensitive poplars.

This article focuses on the genotypic differences in ammonium (NH4⁺) and nitrate (NO3⁻) uptake and their roles in salt tolerance between two contrasting poplar species: salt-tolerant Populus euphratica and salt-sensitive Populus popularis. Under salt stress (100 mM NaCl), both species maintained NH4⁺ uptake, linked to upregulated ammonium transporter (AMT) genes, but differed significantly in NO3⁻ uptake; P. euphratica sustained or increased nitrate uptake and transport associated with upregulated nitrate transporter (NRT) and plasma membrane H⁺-ATPase (HA) genes, whereas P. popularis showed decreased NO3⁻ uptake and downregulation of these genes. The study concludes that the ability of P. euphratica to maintain NO3⁻ uptake under salinity contributes to its greater nitrogen nutrition and salt tolerance compared to P. popularis, highlighting the importance of coordinated regulation of nitrogen transporters and H⁺-ATPases in mitigating salt stress in poplars.