GSE42899
Magnesium Availability Regulates Development of Root Hairs in Arabidopsis thaliana
Root hairs are frequently reported to be plastic in response to nutrient supply, but relatively little is known about their development in response to magnesium (Mg) availability, and evidence is scarce about the signals involved in this process. Here, we showed that both density and length of root hairs of Arabidopsis decreased logarithmically with increasing Mg supply in the media , which correlated with the initiation of new trichoblast files and likelihood of trichoblasts to form hairs. Low Mg resulted in greater concentrations of reactive oxygen species (ROS) and Ca2+ in the roots and displayed a stronger tip-focused gradient of ROS and cytosolic Ca2+ concentration ([Ca2+]c) during initiation and elongation of root hairs. This gradient could be eliminated by DPI or BAPTA. Application of either DPI or BAPTA to low Mg treatment blocked the enhanced development of root hairs. The opposite was true when the plants under high Mg were supplied with Ca2+ or PMS. Whole-genome transcriptome data revealed that the maximum differential expressed genes involved in ‘stress’, ‘oxidation reduction’, ‘ion transport and homeostasis’ and ‘cell wall organization’. A greater fraction of morphogenetic H-genes and root hair -specific genes as well as genes involved in ‘cell wall structure’ were up-regulated by 7-d treatment of 0.5 µM Mg but down-regulated by 7-d treatment of 10,000 µM Mg. It is concluded that a distinct and previously poorly characterized response of root hair development to Mg availability is presented in Arabidopsis where ROS and Ca2+ are the signaling molecules that control this response. Overall design: Roots were sampled from five-week-cultivated Arabidopsis after 4d and 7 d treatments of low Mg (supplied with 0.5 µM Mg2+) and high Mg (supplied with 10 mM Mg2+).