Abstract
The auxin/indole-3-acetic acid (Aux/IAA) gene family encodes central regulators of plant development and stress adaptation. Eggplant (Solanum melongena), an economically important vegetable crop, is highly susceptible to abiotic stresses, yet its Aux/IAA family remains uncharacterized. This study aimed to systematically characterize the Aux/IAA gene family in eggplant and to explore its potential roles in development and abiotic stress responses using a genome-wide approach. Here, 35 SmIAA genes were identified through comprehensive bioinformatic analyses, including phylogenetic classification, synteny analysis, protein-protein interaction prediction, and qRT-PCR validation. Phylogenetic analysis classified these genes into Clades A and B, encompassing nine subgroups, with subgroup B4 showing lineage-specific expansion and encoding non-canonical Aux/IAA proteins. Expression profiling revealed that SmIAA18 and SmIAA33 were strongly responsive to salt stress, whereas SmIAA1/2/8 were preferentially induced by drought stress. Furthermore, SmIAA8 and SmIAA33 exhibited contrasting responses to IAA treatment, characterized by delayed induction and rapid repression, respectively. This study presents the first genome-wide analysis of the Aux/IAA family in eggplant, elucidating its roles in development and stress adaptation, and provides valuable genetic resources for the molecular breeding of stress-tolerant varieties.