Résumé
We previously reported that cytokinins (CK) induce the fast and specific transcription of
CrRR1, a gene encoding a type A response regulator in
Catharanthus roseus cell cultures. Here, we characterized the
CrHPt1 gene that encodes a histidine-containing phosphotransfer domain.
CrHPt1 was silenced through RNA interference (RNAi) to test its possible implication in the CK signalling pathway. In transgenic lines stably transformed with an intron-spliced construct, the degradation of
CrHPt1 transcripts abolishes the CK inductive effect on
CrRR1 transcription. These result give a new in vivo functional argument for the crucial role of HPt proteins in the CK signalling pathway leading to the expression of the genes encoding type A response regulators. They also show that RNAi is a powerful strategy to turn off the CK signalling circuitry.