Figure 9.

OsABI5 Directly Activates the Transcription of NYC1 and SGR.

(A) The positions of the ABRE binding motif (ACGTG) in the promoters of NYC1, SGR, and NOL and promoter fragments used for the ChIP assay (green horizontal lines) and transactivation assay (orange horizontal lines).

(B) Binding affinity of OsABI5 to the promoters of NYC1, SGR, and NOL in planta examined by ChIP assays. OsABI5-MYC was transiently expressed in protoplasts isolated from 10-d-old wild-type rice seedlings. Fold enrichment of the promoter fragments was measured by immunoprecipitation with an anti-MYC antibody (see “Methods”). Enrichment of a promoter region of an unrelated gene, PP2A, was used as a negative control. The mean and SD values were obtained from four biological samples.

(C) Reporter and effector constructs used in the protoplast transient assay. Each construct also contained the NOS terminator.

(D) The activation of NYC1, SGR, and NOL promoters (−1500 to −1, relative to the start codon) by OsABI5-MYC expression in protoplasts that were incubated in darkness. The 35S promoter and an empty expression vector (35S:MYC) served as negative controls. The mean and SD values were obtained from five reaction mixtures. Asterisks indicate a significant difference compared to the negative control (Student’s t test, **P < 0.01). These experiments were repeated twice with similar results.