Circadian Rhythm and Nitrogen Metabolism Participate in the Response of Boron Deficiency in the Root of Brassica napus

Boron (B) deficiency has been shown to inhibit root cell growth and division. However, the precise mechanism underlying B deficiency-mediated root tip growth inhibition remains unclear. In this study, we investigated the role of , a gene encoding a boric acid channel, in ( ). is expressed in the lateral root cap and contributes to B acquisition in the root tip. Downregulation of enhances B sensitivity in , resulting in reduced shoot biomass and impaired root tip development. Transcriptome analysis was conducted on root tips from wild-type (QY10) and RNAi lines to assess the significance of B dynamics in meristematic cells during seedling growth. Differentially expressed genes (DEGs) were significantly enriched in plant circadian rhythm and nitrogen (N) metabolism pathways. Notably, the circadian-rhythm-related gene exhibited a similar B regulation pattern in to that observed in . Furthermore, mutants with disrupted circadian rhythm ( / / ) displayed heightened sensitivity to low B compared to the wild type (Col-0). Consistent with expectations, B deficiency significantly disrupted N metabolism in roots, affecting nitrogen concentration, nitrate reductase enzyme activity, and glutamine synthesis. Interestingly, this disruption was exacerbated in lines. Overall, our findings highlight the critical role of B dynamics in root tip cells, impacting circadian rhythm and N metabolism, ultimately leading to retarded growth. This study provides novel insights into B regulation in root tip development and overall root growth in .