Figure 5. Model of the functional link of RTH3, RTH5 and RTH6 in root hair formation in maize.

RTH5 produces apoplastic superoxide, which results in cell-wall loosening via hydroxyl radicals and also controls the expression of cellulose biosynthesis genes¹⁰. After cell wall loosening, the transmembrane protein RTH6 is arranged in rosettes and synthesizes cellulose at the plasma membrane⁴⁷ which is extruded to the inner side of the cell wall in the root hair tip and thus reinforces the tubular shaft, while the GPI-anchored COBRA-like cell wall protein RTH3¹³ is involved in the organization of the synthesized cellulose. Glc: Glucose.