AtF-box gene expression fine-tunes Arabidopsis thaliana root development

Root growth is under constant dynamic regulation for optimal response to developmental and environmental stimuli. At the posttranslational level, protein abundance is controlled by proteasomal degradation of targeted proteins. The substrate-specificity of this process is exerted by F-box proteins taking part in the SCFs (SKP1-CULLIN-F-box protein ligase) E3 ubiquitin protein ligases. In this work an Arabidopsis thaliana AtF-box, which regulates leucine homeostasis, was analyzed in the context of root development. Publicly available data sets and reporter lines revealed AtF-box expression in the primary and lateral roots. Aberrant stem cell divisions were detected in the distal stem cells (DSC) of the AtF-box knockdown lines (AtF-boxamiRNA), suggesting that AtF-box is required for the optimal cell division. Microscopic observations revealed the premature exit from cell proliferation and slower cell division activity. Conversely, in AtF-box overexpression (AtFboxOE) lines the cell division phase was prolonged. The root growth rate was respectively reduced and enhanced in the AtF-boxamiRNA and AtF-boxOE lines compared to the control. From the results of these studies, we concluded that the AtF-box gene is important for the fine-tuning of root growth.