The Identification of Family Genes and Their Expression, Function, and Regulation in

Quinoa () is an Andean allotetraploid pseudocereal crop with higher protein content and balanced amino acid composition in the seeds. Ammonium (NH), a direct source of organic nitrogen assimilation, mainly transported by specific transmembrane ammonium transporters (), plays important roles in the development, yield, and quality of crops. Many and their functions have been identified in major crops; however, no systematic analyses of and their regulatory networks, which is important to increase the yield and protein accumulation in the seeds of quinoa, have been performed to date. In this study, the were identified, followed by the quantification of the gene expression, while the regulatory networks were predicted based on weighted gene co-expression network analysis (WGCNA), with the putative transcriptional factors (TFs) having binding sites on the promoters of , nitrate transporters (), and glutamine-synthases (), as well as the putative TF expression being correlated with the phenotypes and activities of GSs, glutamate synthase (GOGAT), nitrite reductase (NiR), and nitrate reductase (NR) of quinoa roots. The results showed a total of 12 members of the family with varying expressions in different organs and in the same organs at different developmental stages. Complementation expression analyses in the triple mep1/2/3 mutant of yeast showed that except for , 11/12 restored the uptake of NH in the host yeast. was found to mainly locate on the cell membrane, while TFs (e.g., , , TFs, , , , , , and ) were predicted to be predominantly involved in the regulation, transportation, and assimilation of nitrogen. These results provide the functions of and their possible regulatory networks, which will lead to improved nitrogen use efficiency (NUE) in quinoa as well as other major crops.