Abstract
Drought stress significantly impacts plant growth, productivity, and yield, necessitating a swift fine-tuning of pathways for adaptation to harsh environmental conditions. This study explored the effects of Arabidopsis BTB-A2.1, BTB-A2.2, and BTB-A2.3, distinguished by their exclusive possession of the Broad-complex, Tramtrack, and Bric-à-brac (BTB) domain, on the negative regulation of drought stress mediated by abscisic acid (ABA) signaling. Promoter analysis revealed the presence of numerous ABA-responsive and drought stress-related cis-acting elements within the promoters of AtBTB-A2.1, AtBTB-A2.2, and AtBTB-A2.3. The AtBTB-A2.1, AtBTB-A2.2, and AtBTB-A2.3 transcript abundances increased under drought and ABA induction according to qRT-PCR and GUS staining. Furthermore, the Arabidopsis btb-a2.1/2/3 triple mutant exhibited enhanced drought tolerance, supporting the findings from the overexpression studies. Additionally, we detected a decrease in the stomatal aperture and water loss rate of the Arabidopsis btb-a2.1/2/3 mutant, suggesting the involvement of these genes in repressing stomatal closure. Importantly, the ABA signaling-responsive gene levels within Arabidopsis btb-a2.1/2/3 significantly increased compared with those in the wild type (WT) under drought stress. Based on such findings, Arabidopsis BTB-A2s negatively regulate drought stress via the ABA signaling pathway.