The AMT1 family comprises major ammonium transporters in rice roots. In this study, we utilized AMT1 RNAi mutants (amt1) to explore how AMT1 affects NH₄⁺- and NO₃^–-mediated morphological development and NH₄⁺-responsive gene expression in roots. In the presence of NH₄⁺, amt1 showed inhibition of NO₃^–- dependent lateral root development. The inhibitory action of NH₄⁺ on lateral root growth was independent of the NO₃^– concentrations supplied to amt1 roots. The results of split root assays indicated that NH₄⁺ exerts systemic action in inhibiting NO₃^–-dependent lateral root development in amt1. Further study with NAA and NOA, a potent auxin flux inhibitor, suggested that perturbation of membrane dynamics might not be the primary cause of the inhibitory action of NH₄⁺ on NO₃^–-mediated lateral root growth in amt1 mutants. RNA-seq analysis of NH₄⁺-responsive genes showed that approximately half of DEGs observed in wild-type roots were not detected in the DEGs of amt1 roots. Gene ontology enrichment analysis suggested that the expression of specific functional gene groups were affected by amt1 during the early response to NH₄⁺. Auxin-responsive gene expression and root gravity responses were altered in amt1. This study demonstrated that AMT1 affects the interactions not only between ammonium and nitrate in lateral root growth but also between auxin and NH₄⁺ in rice roots.

该AMT1家族包括水稻根系主要铵转运。在这项研究中，我们利用AMT1 RNAi的突变体（AMT1），探讨如何AMT1影响NH ₄ ⁺ -和NO ₃ ^-介导的形态发育和NH ₄ ⁺响应性基因在根中的表达。在NH 3的存在下₄ ⁺，AMT1表明NO抑制₃ ^- -依赖的侧根发育。NH的抑制作用₄ ⁺上侧根生长不依赖于NO的₃ ^-提供给amt1根的浓度。分裂根测定的结果表明，NH ₄ ⁺发挥全身作用在抑制NO ₃ ^-中-依赖性侧根发育AMT1。与NAA和NOA，一种有效的植物生长素通量抑制剂，进一步的研究表明，膜动力学的扰动可能不是NH的抑制作用的主要原因₄ ⁺对NO ₃ ^-介导的侧根生长AMT1突变体。NH ₄ ⁺响应基因的RNA-seq分析表明，在野生型根中观察到的DEG大约一半未在amt1的DEG中检测到根。基因本体富集分析表明，在对NH ₄ ⁺的早期反应中，amt1影响特定功能基因组的表达。生长素应答基因的表达和根重力应答在amt1中发生了变化。这项研究表明，AMT1不仅影响侧根生长中铵与硝酸盐之间的相互作用，而且影响水稻根中生长素与NH ₄ ⁺之间的相互作用。