Figure 2.

Functions of ethylene in the regulation of photosynthesis under salinity stress. In the absence of ethylene, salinity stress results in an imbalance of Na⁺/K⁺ homeostasis, which leads to the production of ROS. This salinity-induced ROS production, in turn, exerts oxidative stress on plants, resulting in stomatal closure and reduced activity of CO₂-fixing enzymes, resulting in a decrease in photosynthesis. In the presence of ethylene, Na⁺/K⁺ homeostasis and nutrients homeostasis are maintained, and the antioxidant defense mechanism is activated, which limits ROS production, thereby preventing ROS-induced oxidative stress. In the absence of oxidative stress, the rate of photosynthesis is maintained even during salinity stress.