Genome-Wide Identification, Systematic Evolution, and Ethylene-Induced Response Characteristics of the Banana WRKY Gene Family During Fruit Ripening

This study conducted a genome-wide identification and systematic evolutionary analysis of the banana WRKY gene family using bioinformatics, transcriptomics, and molecular biology approaches. A total of 153 WRKY genes were identified in the banana genome, with significant differences in the amino acid count, molecular weight, and other physicochemical properties of their encoded proteins. The subcellular localization of these proteins is primarily in the nucleus. These genes are unevenly distributed across 11 chromosomes, with the highest density on chromosome 7. WRKY gene family members exhibit diverse expression patterns during fruit development and ripening, and some can respond to multiple abiotic and biotic stresses. Systematic evolutionary analysis classified them into three major groups (I, II, and III), with Group II having the highest number of members, which are further divided into five subgroups. Conserved motif analysis revealed that Motif1, Motif2, and Motif4 are key structural elements in the family’s evolution, with some members having a WRKYGKK variant. The gene structure shows a wide range of exon numbers (1–22), and the promoter regions are rich in cis-elements related to light response, hormone signaling, and stress response, indicating their potential for integrating light signals, hormone networks, and multiple stress responses. Collinearity analysis identified 116 segmental duplication events, with Ka/Ks values all less than 1, indicating purifying selection. After ethylene treatment, 51 genes showed significant changes in expression, which can be categorized into four patterns: sustained upregulation, sustained downregulation, initial upregulation followed by downregulation, and delayed upregulation. Among these, MaWRKY10, MaWRKY88, and MaWRKY137 exhibited significant expression changes and may play key roles in fruit ripening. These findings significantly contribute to the theoretical framework regarding the evolution and function of the WRKY family in plants. Moreover, they offer valuable gene resources and regulatory strategies that enhance postharvest banana preservation and molecular breeding efforts.