Dynamic Traits of Intracellular Water and Salt Based on Electrophysiological Measurements During Adaptations of Three Mangrove Species Under Salinity Stresses

Mangroves are landscape plants in coastal parks and are also typical salt-tolerant plants. Water–salt transport plays a key role in their adaptations to salinity. This research aims to study the synchronous dynamics of intracellular water–salt and plant adaptation mechanisms. Therefore, no salt and three salinity gradients, including 0.1, 0.2, and 0.4 mol/L NaCl, were applied to three mangrove plants. An electrophysiological sensor was used to non-invasively detect plant electrical signals. The results showed that mangroves’ water and salt dynamic characteristics differed under salt treatment. Rhizophora stylosa reduced the cytoplasmic salt by increasing water absorption, enhancing salt exclusion, and decreasing salt inflow. Kandelia candel managed salt by transferring it into a vacuole, diluting the intracellular salt concentrations through increased cell fluid while maintaining the salt exclusion capacity as salinity increased. Aegiceras corniculatum decreased the cellular salt influx and adapted to 0.4 mol/L NaCl by activating salt secretion. In addition, water-use, salt transport, cellular endogenous convertible energy, and photosynthetic gas exchange parameters could be used as representative factors for salt adaptation of these mangrove species. The results deepen our understanding of plant salt tolerance mechanisms and provide a new approach for timely determining plant adaptability.