Mechanistic links between KNOXI and CUC genes during Arabidopsis developmen

SPINELLI, S.V.; MARTIN, ANA PAULA; VIOLA, I.L.; GONZALEZ, D; PALATNIK, J.F.

Puerto Madryn

Congreso; 46 Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology; 2010

In Arabidopsis, the KNOXI class of transcription factors comprisesSTM, KNAT1, KNAT2 and KNAT6. These proteins are required toestablish and maintain the shoot apical meristem, while themeristem boundaries are determined by CUP SHAPEDCOTYLEDON (CUC) transcription factors. In many species, thesegenes interact also during leaf morphogenesis and sculpt organswith different shapes and are regulated by microRNA miR164.While much is known about CUC1 and CUC2, and theirquantitative regulation by miR164, mechanistic information abouttheir connection with KNOXI transcription factors is still missing.In this work, we demonstrate that the induction of STM caused theup-regulation of CUC expression in Arabidopsis thaliana.Continuous expression of STM in the leaf primordia causes theactivation of CUC1-3, as well as microRNA MIR164a, whichprovides a negative feedback-loop by post-transcriptionallyregulating CUC1 and CUC2. Detailed promoter studies allowed usto pinpoint relationships between these genes. Furthermore, wefound that precise expression of miR164 targets inside the STMexpression domain is necessary for organ separation duringArabidopsis inflorescence development.