Control of cell proliferation and elongation by miR396

ERCOLI F; ROJAS, ARANTXA L.M.; DEBERNARDI, JM; PALATNIK, J.F.; RODRIGUEZ, R E

Plant Signaling & Behavior

Landes Bioscience

Año: 2016

1559-2324

The combinatory effects of cell proliferation and cell elongation determines the rate at which organsgrowth. In the root meristematic zone cells both divide and expand, while post-mitotic cells in theelongation zone only expands until they reach their final size. The transcription factors of the GROWTHREGULATING FACTOR (GRF) class promote cell proliferation in various plant organs. Their expression isrestricted to cells with a high proliferative capacity, yet strong downregulation of the GRF activitycompromise the plant survival. Part of expression pattern of the GRFs is ensured by the posttranscriptional repression mediated by the conserved microRNA miR396. Here we show the quantitativeeffects in root growth caused by GRF depletion in a series of transgenic lines with different miR396 levels.We show that high miRNA levels affect cell elongation and proliferation in roots. Detailed analysissuggests that cell proliferation is restricted due to a reduction in cell cycle speed that might result fromdefects in the accumulation of mitotic cyclins. The results provide insights into the participation of themiRNA-GRF regulatory network in root development.