摘要At the physiological level,the interplay between auxin and ethylene has long been recognized as crucial for the regulation of organ abscission in plants.How-ever,the underlying molecular mechanisms remain unknown.Here,we identified transcription factors involved in indoleacetic acid(IAA)and ethylene(ET)signaling that directly regulate the expression of IN-FLORESCENCE DEFICIENT IN ABSCISSION(IDA)and its receptor HAESA(HAE),which are key com-ponents initiating abscission.Specifically,litchi IDA-like 1(LcIDL1)interacts with the receptor HAESA-like 2(LcHSL2).Through in vitro and in vivo experiments,we determined that the auxin response factor LcARF5 directly binds and activates both LcIDL1 and LcHSL2.Furthermore,we found that the ETHYLENE INSENSITIVE 3-like transcription factor LcEIL3 di-rectly binds and activates LcIDL1.The expression of IDA and HSL2 homologs was enhanced in LcARF5 and LcEIL3 transgenic Arabidopsis plants,but re-duced in ein3 eil1 mutants.Consistently,the ex-pressions of LcIDL1 and LcHSL2 were significantly decreased in LcARF5-and LcEIL3-silenced fruitlet abscission zones(FAZ),which correlated with a lower rate of fruitlet abscission.Depletion of auxin led to an increase in 1-aminocyclopropane-1-carboxylic acid(the precursor of ethylene)levels in the litchi FAZ,followed by abscission activation.Throughout this process,LcARF5 and LcEIL3 were induced in the FAZ.Collectively,our findings suggest that the mo-lecular interactions between litchi AUXIN RESPONSE FACTOR 5(LcARF5)-LcIDL1/LcHSL2 and LcEIL3-LclDL1 signaling modules play a role in regulating fruitlet abscission in litchi and provide a long-sought mechanistic explanation for how the interplay be-tween auxin and ethylene is translated into the mo-lecular events that initiate abscission.