Rice Ethylene Receptors Define a Novel Plant Hormone Receptor-Ion Channel with Calcium/Cation Permeability

Here, we identify a calcium-dependent antagonism of ethylene response (CAER) regulating root elongation in the model cereal Oryza sativa. Unexpectedly, we show that the ethylene receptor OsERS1 acts as a Ca²⁺-permeable, non-selective cation channel, mediating permeation of both mono- and divalent cations.

Mutagenesis analyses reveal that OsERS1 channel activity relies on homomeric assembly sites (C4/C6) rather than its ethylene-binding domain (C65), indicating decoupled regulatory modules for receptor and channel functions. Genetic data demonstrate that, unlike wild-type plants, both the loss-of-function mutant Osers1 and gain-of-function line Osers2d fail to exhibit CAER phenotypes, establishing that CAER depends on ethylene receptors of OsERS1 and OsERS2.