Structural and Functional Diversity of Serine Protease-Like DEG Genes in Potato

Deg proteases are ATP-independent serine endopeptidases found in bacteria, archaea, and eukaryotes including plants. They are considered to be key regulators of development and stress tolerance in plants. In this study, a comprehensive genome-wide analysis identified 19 serine protease-like DEG family proteins in potato (Solanum tuberosum L.), revealing their structural diversity, domain architecture, and regulatory potential. Physiochemical profiling showed a predominance of acidic isoelectric points (pI), variable protein lengths (169–1083 amino acids), and differential stability indices. Subcellular localization predicted most DEG proteases to reside in the chloroplast, with others distributed across cytoplasm, nucleus, mitochondria, and peroxisome. Domain analysis confirmed the universal presence of the trypsin domain, with varying numbers of PDZ domains and additional conserved motifs among paralogs. Gene ontology annotations linked DEG proteases to key biological functions including PSII repair, photoinhibition, and chloroplast organization, alongside protein catabolism and light stimulus response. Promoter analysis revealed an abundance of cis-regulatory elements (CREs), particularly light-responsive motifs, along with hormone and stress-related elements such as ABRE, ARE, and MBS. Expression profiling across eight developmental tissues demonstrated tissue-specific expression patterns, with strong transcript accumulation of selected DEG members in senescent leaf, stolon, shoot apex, and tuber. Interestingly, several splice variants showed unique expression dynamics, including stage-specific and stress-induced activation. Upon exposure to abiotic and hormonal cues, 16 DEG proteases displayed significant transcriptional modulation, particularly under light, ABA, and Zeatin treatments, with notable fold changes reaching up to 26-fold in certain variants. These findings highlight the functional versatility of DEG proteases in potato development and stress adaptation, especially their responsiveness to light and hormonal stimuli. The characterization of these proteases paves the way for future studies on their roles in crop resilience and genome editing applications.