Identification and intra-genus conservation analysis of non-conventional peptides in hybrid poplar 84K

The functional roles of non-conventional peptides (NCPs) encoded by short open reading frames (sORFs) are increasingly recognized. However, their evolutionary conservation among closely related species remains largely unexplored. This study presented a genome-wide identification of NCPs in the hybrid poplar 84K (P. alba × P. glandulosa), and analyzed NCPs' sequence conservation across six sections of the Populus genus. Using LC-MS/MS with a custom six-frame-translated genome database, 516 conventional peptides (CPs), and 337 NCPs were indentified. NCPs exhibited distinct properties, including shorter length and lower molecular weight, compared to CPs. Tissue-specific expression patterns were prominent, with peptides functionally linked to photosynthesis in leaves, cell wall biosynthesis in stems, and nutrient uptake in roots. Allelic analysis revealed a parent-of-origin expression bias for over 10% of peptides, each set enriched in distinct metabolic pathways. Notably, NCP sequences were significantly less conserved than CPs across the genus, though specific conserved motifs were identified. This work provides the first systematic NCP resource for a model hybrid tree, establishing a foundational platform for leveraging peptide biology in molecular forestry and hybrid breeding.