AUXIN RESPONSE FACTOR3 Regulates Compound Leaf Patterning by Directly Repressing Expression in .

Diverse leaf forms can be seen in nature. In encoding a Cys(2)His(2) transcription factor is a key regulator of compound leaf patterning. PALM1 negatively regulates expression of , a key regulator of lateral leaflet initiation. However, how itself is regulated is not yet known. To answer this question, we used promoter sequence analysis, yeast one-hybrid tests, quantitative transcription activity assays, ChIP-PCR analysis, and phenotypic analyses of overexpression lines and mutant plants. The results show that AUXIN RESPONSE FACTOR3 (MtARF3) functions as a direct transcriptional repressor of . MtARF3 physically binds to the promoter sequence in yeast cells. MtARF3 selectively interacts with specific auxin response elements (AuxREs) in the promoter to repress reporter gene expression in tobacco leaves and binds to specific sequences in the promoter . Upregulation of or removal of both () and () pathways resulted in compound leaves with five narrow leaflets arranged in a palmate-like configuration. These results support that MtARF3, in addition as an adaxial-abaxial polarity regulator, functions to restrict spatiotemporal expression of , linking auxin signaling to compound leaf patterning in the legume plant