Genome-wide identification and expression analysis of GDSL-type esterases/lipases (GELP) gene family in apple (Malus × domestica Borkh.)

The GDSL-type esterase/lipase family plays a crucial role in regulating plant growth and development, modulating responses to abiotic stresses, activating pathogen defense mechanisms, and governing lipid metabolism pathways. In this study, a comprehensive genome-wide analysis using integrated BLASTP and HMMSEARCH strategies identified 38 MdGELP genes in apple, which were mapped to 14 chromosomes. Phylogenetic analysis classified these genes into three major clades (A, B, and C). Multiple sequence alignment, combined with analyses of conserved domains and motifs, revealed a high degree of sequence conservation among MdGELP proteins. Promoter cis-acting element analysis uncovered diverse regulatory motifs, while gene duplication analysis indicated that segmental and tandem duplications were the primary evolutionary forces driving the expansion of the GELP family in apple. Collinearity analysis further highlighted significant homology between MdGELPs and AtGELPs. Quantitative expression assays revealed tissue-specific expression patterns, with MdGELPs showing preferential expression in leaves and flowers. Expression profiling under abiotic stresses (ABA, low-temperature, and salt) demonstrated their positive responsiveness to environmental challenges. This study not only establishes a theoretical foundation for exploring the biological functions of MdGELPs but also provides critical insights for future research in this field.