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Plants have evolved well adaptive responses in root system architecture to cope with changing environments.Nevertheless,the molecular bases of plants translating environmental stimuli to developmental signals are largely unknown.Here,a role for WRKY transcription factors in environment-dependent root branching has emerged.We present a case for WRKY46,whose expression is regulated by both ABA dependent-and ABA independent-signals in osmotic/salt stress conditions.Lack of WRKY46 significantly reduces,while overexpression of WRKY46(OV46)enhances lateral root(LR)development under the stress.We show that exogenous auxin largely restores LR development in wrky46 mutants,that expression of the DR5:GUS auxin response reporter is reduced in roots of wrky46 mutants,and that both wrky46 mutants and OV46 display altered root levels of free indole-3-acetic acid(IAA)and IAA conjugates.Subsequent RT-qPCR and ChIP-qPCR experiments indicate that WRKY46 directly regulates the expression of ABI4 and of genes regulating auxin conjugation,and analysis of wrky46 abi4 double mutant plants confirms that ABI4 acts downstream of WRKY46.Thus,our results demonstrate that WRKY46 contributes to the feedforward inhibition of osmotic/salt stress-dependent LR inhibition via regulation of ABA signaling and auxin homeostasis.Besides,we also show some other WRKYs in LR regulation in response to different environmental stimuli(e.g.phosphate starvation).The accumulating evidences will shed light on the critical roles of WRKY genes in transducing externally environmental signals to internally developmental signals in regulation of root branching.