Objective  This study aims to systematically identify members of the DnaJ gene family in wax gourd (Benincasa hispida), clarify their subfamily classification, gene structure, evolutionary relationships and tissue-specific expression patterns, laying a basis for in-depth analysis of their biological functions in wax gourd.

Method The DnaJ gene family members were identified based on the wax gourd whole-genome data. Bioinformatics analysis was performed to characterize their chromosomal localization, protein physicochemical properties, gene structure, phylogenetic relationships, gene duplication events, and promoter cis-acting elements. Additionally, the expression patterns of DnaJ genes in different tissues were examined via RT-qPCR.

Result A total of 65 DnaJ family members were identified in wax gourd. Based on the phylogenetic tree, they were classified into seven subfamilies. Among them, five pairs of genes exhibited collinearity relationships, and 45 pairs showed homology with Arabidopsis DnaJ genes. These members were distributed across all 12 chromosomes, with chromosome 9 having the highest distribution count of 9 members. Promoter region analysis revealed that these family members were significantly enriched with various cis-acting elements related to light response, hormone (such as abscisic acid and gibberellin) response, and stress conditions (such as drought and low temperature). Tissue-specific expression analysis revealed distinct expression patterns among different DnaJ genes. For example, Bhi02M001163, Bhi09M000795, and Bhi10M001058 showed highest expression in female flowers, Bhi11M001536 was most highly expressed in male flowers, and Bhi05M001234 and Bhi09M002103 exhibited highest expression in apical buds.

Conclusion This study systematically identified the members of the DnaJ gene family in wax gourd, revealing their evolutionary characteristics and expression patterns. It provides an important theoretical foundation for elucidating the functions and regulatory mechanisms of this gene family in wax gourd growth, development, and stress responses.