Role of Calcium and Other Ions in Directing Root Hair Tip Growth

The study investigated the role of calcium (Ca2+), potassium (K+), and hydrogen (H+) ions in the growth of root hairs in Limnobium stoloniferum, using ion-selective microelectrodes. It was found that Ca2+ and H+ influxes were concentrated at the tips of growing root hairs, indicating their potential role in directing growth, while K+ uptake was uniform. The study revealed that aluminum (Al) inhibited root hair growth by blocking Ca2+ influx at higher concentrations (20 μM), but even at lower concentrations (2 μM), growth was inhibited without affecting Ca2+ fluxes, causing swelling similar to effects seen with microtubule inhibitors. This suggested that Al might affect multiple sites on the plasma membrane and within the cell.