The vacuolar H+/Ca transporter CAX1 participates in submergence and anoxia stress responses (Plant Physiol)

Calcium (Ca) signaling is one of the primary plant responses to confront abiotic stresses. To coordinate Ca levels in the different compartments of the cell, several transporters are needed including the H⁺/Ca exchangers (CAXs) in the tonoplast (vacuolar membrane). While the role of calcium signaling has been studied for osmotic and salt stresses in plants, little is known about the role of calcium in responding to submergence stress. Submergence leads to several stresses, from limited light availability to the oxidative stress produced after hypoxic periods. In this work, Yang et al. analyzed CAX1, an exchanger that pumps Ca from the cytoplasm to the vacuole. The authors described that in Arabidopsis thaliana, cax1 mutants show an exceptional tolerance to submergence and anoxic stresses, resembling plants primed in advance for facing these stresses. Post-anoxia, lower levels of Reactive Oxygen Species (ROS) were found in cax1 lines. Finally, it was also demonstrated that cax1 line showed a different Ca signature during reoxygenation than control plants. Overall, this is one of the first works that shows how a tonoplast localized H⁺/Ca transporter can influence anoxia tolerance in plants. (Summary by Eva María Gómez Álvarez, @eva_ga96). Plant Physiol. 10.1093/plphys/kiac375