MLO-Mediated Ca2+ Influx Regulates Root Hair Tip Growth in Arabidopsis

This study investigates the role of MILDEW RESISTANCE LOCUS-O (MLO) proteins in regulating calcium dynamics and root hair tip growth in Arabidopsis. Using a constitutively active MLO (faNTA), researchers identified a new role for the FER/MLO signaling module in controlling [Ca 2+] cyt oscillations in root hairs. The study demonstrated that faNTA can restore normal root hair development, calcium oscillations, and reactive oxygen species (ROS) levels in fer-4 mutants. MLO15 was identified as a key regulator of root hair tip growth, with disrupted growth and calcium signatures observed in mlo15-4 mutants. The research links the FER/MLO module to ROS accumulation, showing that faNTA restores ROS levels in fer-4 root hairs but cannot complement the burst root hairs of rbohc. The findings suggest that MLOs act downstream of FER to mediate calcium influx and promote ROS production, essential for root hair tip growth.