Abstract
We report here that functional analysis of the family of TEOSINTE BRANCHED1, CYCLOIDEA and PCF (TCP) transcription factors in Arabidopsis. Expression of the chimeric TCP3 repressor, in which a member of Arabidopsis TCP transcription factors was fused to the EAR-motif repression domain, resulted in formation of ectopic shoots on cotyledons and various defects in organ development. The chimeric TCP3 repressor induced ectopic expression of boundary-specific genes including CUP-SHAPED COTYLEDON (CUC) genes associated with reduction of accumulation of miR164, which cleaves CUC transcripts. By contrast, gain of function of TCP3 suppressed the expression of CUCs and resulted in the fusion of cotyledons and defects in the shoot apical meristem. The TCP3 transcript was accumulated in cotyledons, but not at the cotyledon boundary where CUCs are functioning. Results demonstrate that the TCP3 is a negative regulator of CUCs in cotyledons and controls morphogenesis of shoot organs and formation of shoot meristems.
