Genome-wide identification and stage-specific expression profiling of single domain serine peptidases in the yellow mealworm, Tenebrio molitor (L.).

Serine peptidases (SP) are crucial proteolytic enzymes involved in food digestion and other processes, including participation in the regulation of signal transduction in response to developmental or pathological cues. This study presents a genome-wide investigation of SPs comprising less than 300 amino acid residues and containing a single catalytic peptidase domain in the yellow mealworm Tenebrio molitor (L.), a globally distributed species that infests stored cereals and other food products. Detailed analyses of gene structures (exon-intron pattern), chromosomal localization, and transcriptional orientation revealed numerous SP-encoding loci spread across nine chromosomes of the T. molitor genome. Most of these genes are organized in tandem arrays, forming clusters of closely related genes, thus suggesting that the SP gene family has undergone substantial expansion through gene duplication events. Phylogenetic gene family analysis further uncovered potential displaced duplications resulting from intra- and/or inter-chromosomal gene movements. Gene expression profiling across developmental stages revealed diverse expression patterns, pointing to previously unrecognized physiological roles of single domain SPs beyond their well-established function in digestion. Overall, this study provides a comprehensive resource on insect SP genes and their developmental expression profiles.