Guard cells are paired, crescent-shaped cells that surround stomata, and control gas exchange in leaves. Stomata are sensitive structures that help plants manage their water use and photosynthesis by regulating gas exchange and transpiration. Guard cells can change their shape in response to environmental cues like light and temperature to optimize gas exchange while minimizing water loss.
The walls on the inner and outer surfaces of guard cells vary in thickness, creating a hinge-like action when the cells swell and shrink. When the guard cells are turgid, they bow apart, pushing the stoma open so that carbon dioxide can enter the leaf, and oxygen can exit. When the water supply becomes scarce, the guard cells will lose turgor and fold to close the stomata, conserving water and restricting carbon dioxide uptake, thus reducing photosynthesis.
Guard cells serve as the gatekeepers of photosynthesis because they control the movement of gases that are required for this process to take place. Photosynthesis is a vital process in plants and produces the oxygen we breathe. By controlling the opening and closing of stomata, guard cells regulate the exchange of gases and help manage photosynthesis in plants.
The role of guard cells is critical for plant survival, especially when plants are exposed to environmental stress. During drought, the guard cells reduce the rate of transpiration by closing the stomata. Similarly, during hot and dry conditions, the guard cells reduce water loss by controlling stomatal opening. Conversely, guard cells open the stomata for carbon dioxide uptake in low CO2 conditions, enhancing photosynthesis.
In conclusion, guard cells are essential to the survival of plants and play a crucial role in regulating gas exchange and photosynthesis. They adapt to environmental cues like light intensity, humidity, and temperature, and respond quickly to protect the plant from stress. Understanding the function of guard cells offers ways of improving crop productivity, managing climate change and developing new stress-tolerant crop varieties.