The peptide hormone RGF1 modulates PLETHORA2 stability via reactive oxygen species-dependent regulation of a cysteine residue.

The Root meristem growth factor 1 (RGF1) peptide extends the PLETHORA2 (PLT2) protein gradient by altering the distinct localization of superoxide (O2-) and hydrogen peroxide (H2O2) among the root developmental zones. However, the underlying mechanism through which reactive oxygen species (ROS) regulate PLT2 stability is unclear. Here, we demonstrate that the 212th cysteine of PLT2 is pivotal in modulating PLT2 stability through ROS. The PLT2 protein concentration gradient rapidly decreases in the elongation zone, where H2O2 accumulation initiates. However, substituting the 212th cysteine of PLT2 with serine (PLT2C212S) results in PLT2 being more stable in the elongation zone, more broadly localized by RGF1, and showing robust resistance to H2O2. The sulfenylation of PLT2 was detected following treatment with H2O2 at high concentrations, suggesting that S-sulfenylation of the 212th cysteine controls PLT2 protein stability through local ROS distributions. These findings show that the formation of the PLT2 concentration gradient through ROS depends on a PLT2 sulfenylation mechanism that involves the 212th cysteine.