The Genome-Wide Identification and Expression Analysis of the AMT Gene Family in Foxtail Millet

Ammonium transporters (AMTs) represent a class of proteins within the ammonium transporter domain, which play an important role in mediating the transmembrane transport of NH₄⁺ in plants. However, research on AMT genes in foxtail millet remains limited. In this study, members of the AMT gene family in foxtail millet were identified at the whole genome level through bioinformatic analysis. The gene structure, evolutionary relationships, chromosomal localization, interspecies collinearity, cis-acting elements, and expression patterns of SiAMT members were systematically analyzed. The results revealed that there were nine SiAMT family members in foxtail millet, with molecular weights ranging from 49.5 to 53.8 kDa. Phylogenetic analysis classified them into three groups, which were unevenly distributed across chromosomes. The analysis of promoter cis-acting elements identified multiple regulatory elements, including light-, anaerobic-, and hormone-responsive elements. Collinearity analysis showed that the divergence time of AMT family members in foxtail millet and rice was more recent compared to Arabidopsis thaliana. The expression levels of SiAMT members varied across different tissues of foxtail millet, with most SiAMT family members showing high expression in roots, while SiAMT7 was significantly expressed in leaves. qRT-PCR analysis showed that SiAMT1 was significantly down-regulated in roots, stems, and leaves under salt stress. This study provides a theoretical foundation for further investigation into the functions of the AMT gene family.