Genome-Wide Exploration of the WD40 Gene Family in Eggplant (Solanum melongena L.) and Analysis of Its Function in Fruit Color Formation

The WD40 gene family is a highly conserved protein family in plants that plays a crucial role in various life activities. Although eggplant (Solanum melongena L.) genome sequencing has been completed, there is limited research on the WD40 family in eggplant, and the regulatory mechanism of its involvement in anthocyanin synthesis remains poorly understood. The research identified the eggplant WD40 gene family, comprising 187 SmWD40 members that are unevenly distributed across 12 chromosomes of the eggplant. Phylogenetic analysis classified them into 11 subgroups, with members within the same subgroup having similar motifs and gene structures. The promoter of the SmWD40 genes contains a high number of light, stress, and hormone response elements. The expression patterns of 20 SmWD40 members of the S5 subgroup were analyzed during the formation of fruit color in long purple eggplant. Subsequently, we used virus-induced gene silencing (VIGS) to confirm the significance of the TTG1 (SmWD40-56) gene in subgroup S5 for anthocyanin synthesis in eggplant fruit. To investigate the molecular mechanism of SmWD40-56 in eggplant fruit color formation, we analyzed the expression patterns of structural genes for anthocyanin synthesis in eggplant fruit silenced for SmWD40-56. Finally, we predicted the protein interaction network of the SmWD40-56 gene to understand its potential regulatory mechanisms. The result showed that SmWD40-56 may regulate the structural genes involved in anthocyanin biosynthesis and plays an important role in eggplant fruit color formation. This study provides some basis for studying the mechanism of eggplant fruit color formation.