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

The study investigates the role of MILDEW RESISTANCE LOCUS-O (MLO) proteins in regulating calcium dynamics and reactive oxygen species (ROS) accumulation during root hair tip growth in Arabidopsis. It identifies a new function for the FERONIA (FER)/MLO signaling module, showing that a constitutively active MLO (faNTA) can bypass FER signaling to restore calcium oscillations and ROS levels in fer-4 mutant root hairs. This restoration complements the disrupted growth and polarity seen in these mutants, suggesting that MLOs are crucial for maintaining root hair tip integrity. MLO15, in particular, is highlighted as a key regulator, with its disruption leading to altered root hair growth and calcium signatures. The findings propose that MLOs act downstream of FER to mediate calcium influx and promote ROS production, essential for root hair tip growth. Understanding these mechanisms could enhance root responses to environmental challenges.