Genome-Wide Identification and Expression Analysis of the Copper Transporter (<i>COPT</i>/<i>Ctr</i>) Gene Family in <i>Kandelia obovata</i>, a Typical Mangrove Plant

The copper transporter (<i>COPT</i>/<i>Ctr</i>) gene family plays a critical part in maintaining the balance of the metal, and many diverse species depend on <i>COPT</i> to move copper (Cu) across the cell membrane. In <i>Arabidopsis thaliana</i>, <i>Oryza sativa</i>, <i>Medicago sativa</i>, <i>Zea mays</i>, <i>Populus trichocarpa</i>, <i>Vitis vinifera</i>, and <i>Solanum lycopersicum,</i> a genome-wide study of the COPT protein family was performed. To understand the major roles of the <i>COPT</i> gene family in <i>Kandelia obovata</i> (<i>Ko</i>), a genome-wide study identified four <i>COPT</i> genes in the <i>Kandelia obovata</i> genome for the first time. The domain and 3D structural variation, phylogenetic tree, chromosomal distributions, gene structure, motif analysis, subcellular localization, cis-regulatory elements, synteny and duplication analysis, and expression profiles in leaves and Cu were all investigated in this research. Structural and sequence investigations show that most <i>KoCOPTs</i> have three transmembrane domains (TMDs). According to phylogenetic research, these <i>KoCOPTs</i> might be divided into two subgroups, just like <i>Populus trichocarpa</i>. <i>KoCOPT</i> gene segmental duplications and positive selection pressure were discovered by universal analysis. According to gene structure and motif analysis, most <i>KoCOPT</i> genes showed consistent exon–intron and motif organization within the same group. In addition, we found five hormones and four stress- and seven light-responsive cis-elements in the <i>KoCOPTs</i> promoters. The expression studies revealed that all four genes changed their expression levels in response to copper (CuCl₂) treatments. In summary, our study offers a thorough overview of the <i>Kandelia obovata COPT</i> gene family’s expression pattern and functional diversity, making it easier to characterize each <i>KoCOPT</i> gene’s function in the future.