Editor's Evaluation: Plant Trans-Golgi Network/Early Endosome pH Regulation Requires Cation Chloride Cotransporter (CCC1)

The study demonstrated that the Cation Chloride Cotransporter (CCC1) was essential for regulating pH in the trans-Golgi network/early endosome (TGN/EE) in Arabidopsis plants. Loss of CCC1 function led to a more alkaline pH in the TGN/EE lumen, affecting endomembrane trafficking, cell expansion, and cell wall formation, resulting in phenotypic defects such as reduced plant size, increased shoot branching, and altered root hair growth. CCC1 was identified as the first TGN/EE-localized transporter important for pH regulation without directly transporting protons, playing a crucial role in ion concentration regulation and counteracting cation-induced osmotic swelling. The study also found that CCC1 knockouts showed greater tolerance to salt and osmotic stress, highlighting CCC1's central function in plant cellular homeostasis and its role in the TGN/EE ion transport network.