Drylands are environments where the availability of water for plants is extremely low because the amount of precipitation is small and the potential evapotranspiration exceeds the amount of precipitation. Plants acquire carbon through the stomata of leaves to perform photosynthesis, but at the same time, they lose water through transpiration through the stomata. When water is lost from the leaves due to transpiration, the water absorbed by the roots is transported to the leaves through the stem. However, under drought, the water balance in the plant is disrupted because the absorption and transport of water cannot keep up with the loss of water, resulting in drought stress. When plants are subjected to drought stress, a decrease in turgor pressure occurs, leading to wilting and death. In addition, metabolic activity in the protoplasm deteriorates and stomata close, which suppresses photosynthesis and inhibits growth. Therefore, mechanisms to drought stress are important for growth and survival in drylands.