Coding-Sequence Identification and Transcriptional Profiling of Nine and Four From Tobacco Revealed Their Differential Regulation by Developmental Stages, Nitrogen Nutrition, and Photoperiod.

Although many members encoding different ammonium- and nitrate-transporters (AMTs, NRTs) were identified and functionally characterized from several plant species, little is known about molecular components for [Formula: see text]- and [Formula: see text] acquisition/transport in tobacco, which is often used as a plant model for biological studies besides its agricultural and industrial interest. We reported here the first molecular identification in tobacco () of nine and four , which are respectively divided into four () and two () clusters and whose functionalities were preliminarily evidenced by heterologous functional-complementation in yeast or Arabidopsis. Tissue-specific transcriptional profiling by qPCR revealed that / mRNA occurred widely in leaves, flower organs and roots; only were strongly transcribed in the aged leaves, implying their dominant roles in N-remobilization from source/senescent tissues. N-dependent expression analysis showed a marked upregulation of in the roots by N-starvation and resupply with N including [Formula: see text], suggesting a predominant action of NtAMT1.1 in [Formula: see text] uptake/transport whenever required. The obvious leaf-expression of other e.g., responsive to N indicates a major place, where they may play transport roles associated with plant N-status and ([Formula: see text]-)N movement within aerial-parts. The preferentially root-specific transcription of responsive to N argues their importance for root [Formula: see text] uptake and even sensing in root systems. Moreover, of all s/, only / showed their root-expression alteration in a typical diurnal-oscillation pattern, reflecting likely their significant roles in root N-acquisition regulated by internal N-demand influenced by diurnal-dependent assimilation and translocation of carbohydrates from shoots. This suggestion could be supported at least in part by sucrose- and MSX-affected transcriptional-regulation of . Thus, present data provide valuable molecular bases for the existence of s in tobacco, promoting a deeper understanding of their biological functions.