Magnesium Availability Regulates the Development of Root Hairs in Arabidopsis Thaliana (L.) Heynh

The study demonstrated that magnesium (Mg) availability significantly influenced the development of root hairs in Arabidopsis thaliana. As Mg supply increased, root hair development decreased, which was linked to the initiation of new trichoblast files and the likelihood of trichoblasts forming hairs. Low Mg levels enhanced tip-focused reactive oxygen species (ROS) and cytosolic Ca2+ concentrations during root hair elongation, while high Mg levels reduced them. The application of specific chemicals could block or enhance root hair development depending on Mg levels. In the rhd2-1 mutant, which has lower ROS and Ca2+ levels, Mg availability did not affect root hair growth. Transcriptome and qPCR analyses showed that low Mg up-regulated morphogenetic H-genes and cell wall organization genes, whereas high Mg down-regulated them. The findings suggested that Mg supply profoundly affected root hair development through Ca2+ and ROS signaling pathways that modulated root hair elongation and gene expression.