Fig. 4. Misexpression of CO from heterologous promoters. (A) Histochemical localisation of GUS activity in longitudinal sections of promoter::GUS transgenic plants. Shoot apex and cotyledon section of 9-day-old AtSUC2::GUS Ler plant showing phloem-specific expression (pSUC2). Shoot apex and cotyledon section of an 11-day-old F1 plant of CLV1::LhG4xOp::GUS-Op::CO co-2 showing expression in the meristem and phloem (pCLV1). Shoot apex section of an 11-day-old F1 plant of ANT::LhG4xOp::GUS-Op::CO co-2 showing expression in leaf primordia (pANT). Shoot apex section of 9-day-old KNAT1::GUS Ler plant showing expression in meristem (pKNAT). (B) Phenotype of LD-grown co-2 plants carrying transgenic constructs driving CO expression in specific domains. (C) Flowering time of co-2 transgenic plants in which CO is expressed from tissue-specific promoters. Plants were grown either in LDs or in SDs. The minus sign indicates that an experiment was not conducted under SDs. (D) In situ hybridisation of sections of KNAT1::CO co-2 (left) and co-2 mutant (right) plants probed with CO. Arrowheads in D indicate SAM. Scale bars: 100 µm.