Fig. 6. TCL1 suppresses the expression of GL1. (A) RT-PCR analysis of TTG1, GL1, GL2 and GL3 transcripts in Arabidopsis seedlings overexpressing HA-TCL1. Expression of ACTIN2 provided a control. (B) Suppression of GL1::GUS reporter by TCL1. Shown are the expression of GL1::GUS reporter in wild-type (Col) and in 35S:HA-TCL1 backgrounds. In the GL1::GUS reporter, the expression of GUS was driven by a chimerical genomic sequence consisting of the immediate 5' upstream sequence, the first intron, and the 3'-UTR region of GL1 (Wang et al., 2004). (C) RT-PCR analysis of TCL1 transcript in various tissues/organs. Expression of ACTIN2 provided a control. (D) RT-PCR analysis of GL1 and GL2 transcripts in the developing inflorescence of tcl1-1 mutants. Expression of ACTIN2 provided a control.