741 / 2019-05-15 01:07:43

The ins and outs of boundary domain functions in Arabidopsis: looking upstream and downstream of the CUP-SHAPED COTYLEDON transcription factors

Development

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The CUP-SHAPED COTYLEDON (CUC) genes were initially identified for their role in defining the boundary domain around organ primordia in the embryo and the floral meristems. Since then, their known roles have greatly expanded and they have been shown to control multiple aspects of plant aerial organ development. Hence, boundary domain in general and CUC genes in particular have been shown to control meristem function including axillary meristem, phyllotaxy, organ number and position and organ shape. Accordingly, plant architecture is severely affected when CUC genes are misexpressed, underlying the need for these genes to be strictly regulated. Here, I will show how the interplay between Polycomb-Repressing Complex 2 (PRC2)-mediated chromatin remodelling and miRNA-mediated regulation contributes to provide a robust regulation of the activity of the CUC2 gene. This exemplifies how defective transcriptional regulations can be compensated by the activation of a new post-transcriptional regulation and illustrates how the synergistic interactions between two fundamental mechanisms of gene expression regulation allow maintaining robust development despite flexible underlying genetic circuits. Next, I will provide insights into how CUC2 directs morphogenesis by allowing coordination of patterning and growth via the activation of a downstream regulatory network.