Using transcriptome analysis, virus-induced gene silencing, and stable overexpression, SmIAA15 was found to act as a negative regulator of picloram resistance in eggplant through modulating the glutathione metabolism. • Overexpression of SmIAA15 in tobacco reduces resistance to picloram, while silencing SmIAA15 in eggplant enhances picloram resistance. • Transcriptome analysis of SmIAA15 -silenced eggplant lines reveals that enhanced resistance to picloram is associated with increased GST enzyme activity and upregulation of GST-related genes. • Stable transgenic tomato lines overexpressing SmIAA15 display a picloram-induced phenotype and decreased GST enzyme activity, demonstrating the role of SmIAA15 in modulating herbicide resistance. Auxin/indole acetic acid (Aux/IAA) proteins repress the expression of auxin-responsive genes to mediate environmental abiotic stresses. Distinct auxinic herbicides are differentially involved in the auxin signaling pathway, affecting the functional role of specific Aux/IAA members. However, the role of Aux/IAA in modulating the sensitivity of eggplant ( Solanum melongena L.) to the auxinic herbicide picloram remains largely unexplored. This study aims to identify putative Aux/IAA gene family members in eggplant and to characterized their functional roles in response to auxinic herbicide picloram (HRAC, group 4), offering potential molecular targets for the development of herbicide-resistant eggplant. We conducted the genome-wide identification of Aux/IAA gene family members in eggplant and analyzed their expression profiles in response to picloram. We systematically characterized the functional role of SmIAA15 in response to the herbicide picloram and uncovered the molecular mechanisms underlying SmIAA15-mediated sensitivity of eggplant to picloram using a combination of molecular and biochemical approaches. We identified twenty-three putative Aux/IAA gene family members in eggplant. Under picloram treatment, SmIAA15 was significantly induced and localized to the nucleus. Overexpression of SmIAA15 in tobacco notably decreased resistance against picloram, while virus-induced gene silencing of SmIAA15 in eggplant enhanced resistance to picloram. KEGG analysis of transcriptome data from SmIAA15-silenced lines revealed that the enhanced resistance to picloram was associated with the glutathione metabolism pathway, as evidenced by increased glutathione S-transferases (GST) enzyme activity and upregulation of GST-related genes in SmIAA15 -silenced lines. Consistently, stable transgenic tomato lines overexpressing SmIAA15 displayed a picloram-induced phenotype with outwardly curved leaves, and decreased GST activity compared to the non-transgenic controls. Collectively, our findings demonstrate that SmIAA15 acts as a negative regulator in response to picloram by regulating the glutathione S-transferase enzyme activity, potentially contributing to the molecular breeding of picloram-resistant eggplant.
Du et al. (Sun,) studied this question.