Molecular characterization and insilico expression analysis of ammonium transporter genes family in Sorghum bicolor

Nitrogen (N) is an essential macronutrient for plants, primarily absorbed from the soil as ammonium (NH₄⁺) through Ammonium Transporters (AMTs), which are plasma membrane proteins. This study involved the genome-wide identification, characterization, and insilico expression analysis of sorghum (Sorghum bicolor L.) AMT genes (SbAMTs) in different tissues, including flowers, meristems, embryos, roots, and shoots, as well as under treatments with abscisic acid (ABA) and 20% polyethylene glycol (PEG). Structural analyses revealed conserved transmembrane domains, though SbAMT2.2 and SbAMT3.3 exhibited fewer domains due to their small protein size. Gene structure analysis showed significant intron variation between AMT1 and AMT2 families, while motif analysis suggested evolutionary divergence. Secondary and 3D structure analysis indicated that AMTs are predominantly composed of alpha-helices. Synteny analysis revealed strong gene conservation among Poaceae family members, especially with Zea mays. Gene ontology analysis (GO) and protein–protein interaction analysis highlighted roles in ammonium transport, nitrogen metabolism, and stress responses. Cis-element analysis of AMT promoter regions revealed regulatory elements responsive to light, hormones (eg. auxin, gibberellin, abscisic acid), and environmental stresses like drought and anaerobic conditions, suggesting AMTs’ involvement in growth, development, and stress adaptation. Expression profiling revealed tissue-specific patterns, with SbAMT1.2 being highly expressed in roots, and SbAMT3.3 broadly expressed across tissues. Stress-induced upregulation of SbAMT genes under ABA and PEG treatments suggests their involvement in drought tolerance. These findings provide valuable insights into the structure, function, and evolution of AMTs in S. bicolor, with potential applications for improving nitrogen use efficiency and stress resilience in crops.