The ABI3-ERF1 module mediates ABA-auxin crosstalk to regulate lateral root emergence

Abscisic acid (ABA) is involved in lateral root (LR) development, but how ABA signaling interacts with auxin signaling to regulate LR formation is not well understood. Here, we report that ABA-responsive ERF1 mediates the crosstalk between ABA and auxin signaling to regulate Arabidopsis LR emergence. ABI3 is a negative factor in LR emergence and transcriptionally activates ERF1 by binding to its promoter, and reciprocally, ERF1 activates ABI3, which forms a regulatory loop that enables rapid signal amplification. Notably, ABI3 physically interacts with ERF1, reducing the cis element-binding activities of both ERF1 and ABI3 and thus attenuating the expression of ERF1-/ABI3-regulated genes involved in LR emergence and ABA signaling, such as PIN1, AUX1, ARF7, and ABI5, which may provide a molecular rheostat to avoid overamplification of auxin and ABA signaling. Taken together, our findings identify the role of the ABI3-ERF1 module in mediating crosstalk between ABA and auxin signaling in LR emergence. [Display omitted] •ABI3 is a negative factor in LR emergence and transcriptionally activates ERF1•ERF1 transcriptionally activates ABI3•Reciprocal activation between ERF1 and ABI3 rapidly amplifies auxin and ABA signals•The ABI3-ERF1 interaction reduces the cis element-binding activity of ERF1 and ABI3 Lateral root (LR) development is regulated by hormones and environmental signals. Zhang et al. show that ERF1 is responsive to ABA during LR development and mediates the crosstalk between ABA and auxin signaling via the ERF1-ABI3 module in LR emergence.