New Ideas on Root Hair Growth Appear from the Flanks

Monshausen et al. (2007) explored the roles of protons and reactive oxygen species (ROS) in root hair growth in Arabidopsis, revealing that growth occurs in discrete episodes rather than continuously. They found that each growth phase was associated with external pH alkalization and internal cellular acidification, indicating proton influx into the root hair cell. This acidification of the apoplast was hypothesized to enable polar growth by loosening cell wall components just behind the root hair apex, allowing growth to be concentrated at the tip while reinforcing the cell wall at the flanks to prevent expansion.