A spatiotemporally regulated transcriptional complex underlies heteroblastic development of leaf hairs in Arabidopsis thaliana

Heteroblasty refers to a phenomenon that a plant produces morphologically or functionally different lateral organs in an age-dependent manner. In the model plant Arabidopsis thaliana, the production of trichomes (epidermal leaf hairs) on the abaxial (lower) side of leaves is a heteroblastic mark for the juvenile-to-adult transition. Here, we show that the heteroblastic development of abaxial trichomes is regulated by a spatiotemporally regulated complex comprising the leaf abaxial fate determinant (KAN1) and the developmental timer (miR172-targeted AP2-like proteins). We provide evidence that a short-distance chromatin loop brings the downstream enhancer element into close association with the promoter elements of GL1, which encodes a MYB transcription factor essential for trichome initiation. During juvenile phase, the KAN1-AP2 repressive complex binds to the downstream sequence of GL1 and represses its expression through chromatin looping. As plants age, the gradual reduction in AP2-like protein levels leads to decreased amount of the KAN1-AP2 complex, thereby licensing GL1 expression and the abaxial trichome initiation. Our results thus reveal a novel molecular mechanism by which a heteroblastic trait is governed by integrating age and leaf polarity cue in plants.

Source: EMBO Journal - April 14, 2019 Category: Molecular Biology Authors: Wang, L., Zhou, C.-M., Mai, Y.-X., Li, L.-Z., Gao, J., Shang, G.-D., Lian, H., Han, L., Zhang, T.-Q., Tang, H.-B., Ren, H., Wang, F.-X., Wu, L.-Y., Liu, X.-L., Wang, C.-S., Chen, E.-W., Zhang, X.-N., Liu, C., Wang, J.-W. Tags: Development & Differentiation, Plant Biology, Transcription Articles Source Type: research