A quick HYL1-dependent reactivation of microRNA production is required for a proper developmental response after extended periods of light deprivation

ACHKAR NP,; CHO SK; POULSEN C; ARCE AL; RE DA; GIUDICATTI AJ; KARAYEKOV E; RYU MY; CHOI SW; HARHOLT J; CASAL JJ; YANG SW; MANAVELLA PA

DEVELOPMENTAL CELL

CELL PRESS

Lugar: United States; Año: 2018 vol. 46 p. 236 - 247

1534-5807

Light is the most influential environmental stimulus for plants growth. In response to deficient light, plants reprogram their development to adjust their growth in search for a light source. A fine reprogramming of gene expression orchestrates such adaptive trait. Here we show that plants alter microRNAs (miRNAs) biogenesis in response to light transition. When plants suffer an unusual extended period of light deprivation, the miRNA biogenesis factor HYPONASTIC LEAVES 1 (HYL1) is degraded but an inactive pool of phosphorylated protein remains stable inside the nucleus. Degradation of HYL1 leads to the release of gene silencing, triggering a proper response to dark and shade. Upon light restoration, a quick dephosphorylation of the HYL1 leads to the reactivation of miRNA biogenesis and a switch toward a developmental program that maximize the light uptake. Our findings define a unique and fast regulatory mechanism controlling the plant silencing machinery during plant light response.