The miR444f Regulates Root Development via Gibberellin Metabolic Pathway in Rice.

MicroRNAs (miRNAs) are critical regulators of root development, further impacting plant growth and environmental adaptability. As an important miRNA family, the role of MIR444 in the root development of rice remains largely unknown. Here, we observed that loss of miR444f, which belongs to the MIR444 family, exhibited significant developmental defects in primary and lateral roots during early growth stages. Cellular and molecular analyses revealed that miR444f affected growth activity, cell division, and elongation in the root apical meristem. This effect was mediated through its targeting of the MADS-box transcription factors OsMADS27 and OsMADS57, which are key regulators of the gibberellin (GA) metabolic pathway. Subsequently, the expression of GA metabolic genes and GA accumulation were significantly altered. Furthermore, exogenous GA restores root growth defects in miR444f mutants, confirming the central role of the GA signalling pathway in miR444f-regulated root growth. These findings offer strategic insights for optimizing crop root architecture and function through genetic engineering, aimed at enhancing productivity and environmental resilience.