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

Abstract

SummaryLateral root (LR) development is regulated by hormones and environmental signals. Abscisic acid (ABA) is involved in LR development, but it is not well understood how ABA signaling interacts with auxin to regulate LR formation. Here, we report thatArabidopsis ERF1is responsive to ABA during LR development and mediates the crosstalk between ABA and auxin signaling to regulate LR emergence. ABA attenuates ERF1-mediated excessive auxin accumulation with altered distribution known to inhibit LR emergence. ABI3 acts as a negative factor in LR emergence and transcriptionally activatesERF1by binding to the RY motif in its promoter, and reciprocally, ERF1 activatesABI3, which forms a positive regulatory loop that enables rapid signal amplification. Notably, ABI3 physically interacts with ERF1, consequently reducing theciselement-binding activities of both ERF1 and ABI3 and thus attenuating ERF1-regulated transcription ofPIN1,AUX1, andARF7involved in the modulation of LR emergence and ABI3-regulatedABI5in ABA signaling, which may provide a molecular rheostat to avoid overamplification of auxin and ABA signaling. Taken together, our findings unveil the pivotal ABI3-ERF1 module that mediates the crosstalk between ABA and auxin signaling in LR emergence.