New signalling molecules regulating root hair tip growth

Root hairs are tip-growing tubes that emerge from trichoblasts (hair-forming epidermal cells) along the length of the root. Signalling events involved in the formation of root hairs are largely unknown. However, two recent studies have revealed that signalling enzymes such as NADPH oxidase and phospholipase D are crucial for root hair growth and development. Reactive oxygen species (ROS) produced by NADPH oxidase activate calcium ion channels in the apical plasma membrane leading to the tip-focused calcium gradient, an inherent feature of growing root hairs.