Genomic and functional insights into the diversity of Capsicum annuum defensin gene family

Abstract

Plant defensins are known for their diverse functional roles in development and stress tolerance. We explored the structural and functional diversity of the defensin gene family in Capsicum annuum (CanDef) genomes (CM334 and UCD10Xv1.1). A total of 63 unique full-length CanDef genes were identified through BLASTn and BLASTp analysis. The CanDefs possessed ~ 46 to 88 amino acids and categorized into four groups based on their length, presence of C-terminal tail and gamma-core region. Their phylogenetic analysis with other plant and invertebrate defensin proteins resulted in seven clades of which 37 CanDefs aligned in the recently diversified clade. Most CanDefs localized to chromosome-7. CanDefs contained functional motifs like gamma thionin, knot domain or scorpion toxin domain. Cis-elements and miRNA target sites related to phytohormone signaling, stress responses and development were enriched in the upstream of CanDefs and indicated diverse biological functions. In silico RNA-seq analysis revealed unique expression of CanDefs in tissues under different stresses. CanDefs varied their gene expression in stress conditions significantly with CanDef20, CanDef45 and CanDef61 being the most prominently expressed. In choice assay, Helicoverpa armigera larvae were attracted towards Nicotiana tabacum leaves expressing CanDefs, whereas their growth reduced in the no-choice assay. In conclusion, the genomic, molecular and functional insights on CanDef diversity highlight their significance in plant development and response to biotic/abiotic stresses. © King Abdulaziz City for Science and Technology 2025.