Genome-Wide Identification and Expression Analysis of UBP Genes in Peppers (Capsicum annuum L.)

The ubiquitin-specific protease (UBP) family constitutes the largest group within the deubiquitinating enzymes (DUBs) and plays a crucial role in regulating the cell cycle, growth, and developmental processes in living organisms. By utilizing genomic and transcriptomic databases, we employed bioinformatics tools to identify UBP family members within pepper genomes and to analyze the expression profiles of CaUBP genes under various abiotic stresses, as well as in different tissues and organs. Our findings revealed the presence of 40 CaUBPs in peppers, exhibiting significant variation in their physicochemical properties. Subcellular localization studies indicated that all CaUBPs are localized in the nucleus. Phylogenetic analysis categorized the 40 CaUBPs into 11 distinct subfamilies (G1–G11), with the largest subfamily comprising seven members. Members within the same subfamily displayed similar domain and motif structures. The promoter regions of CaUBP genes were found to be enriched with elements responsive to light, stress, and hormones. Syntenic analysis revealed that 12 CaUBPs were mapped to the Arabidopsis thaliana genome, suggesting potential functional conservation. Additionally, tandem duplications were observed in the alignment of two sets of genes within the pepper genome. CaUBPs were implicated in the stress response and organ growth, with CaUBP17/34/35 showing significant changes in expression under heat stress. While most genes were not expressed in leaves, the expression of several genes (CaUBP3/17/27/32/35/38) in flowers was significantly altered. This study establishes a foundation for further exploration of the roles of CaUBPs in pepper growth, development, and stress response mechanisms.