FIGURE 7.

ARF5 and ARF8 are associated with the promoter region of PRE6. (A) ARF-binding sites in the 2 kb sequence upstream of the start codon of PRE6. I, II, and III indicate the regions for PCR amplification; P1 to P6 indicate the primers for PCR reactions. (B) Chromatin immunoprecipitation (ChIP) assay in transfected protoplasts. Plasmids of HA-ARF5 or HA-ARF8 were transfected into protoplasts isolated from rosette leaves of 3 to 4-week-old Col wild type plants, the transfected protoplasts were incubated for 20–22 h at room temperature in darkness, and ChIP assays were performed using anti-HA antibodies. Rabbit pre-immune serum was used as a mock control. Primer sets spanning the auxin response elements were used in PCR reactions. Amplification of ACT7 was used as a control. (C) A model illustrating the role of PRE6 in plant growth and development and auxin singling. ARFs directly activate the expression of PRE6, PRE6 regulates root and hypocotyls elongation, and it also serve as a feedback regulation loop in the regulation of auxin signaling via inhibiting the expression of Aux/IAA genes. Lines in blue indicate previously known results, and lines in black indicate results reported in this research.