Guard cells are specialized cells found in the leaves of the plants, surrounding the stomata, the small pores responsible for gas exchange in the plants. The primary function of guard cells is to regulate the opening and closing of stomata, which helps the plants in several ways.
Photosynthesis is the fundamental process through which plants produce food for their survival. Guard cells are responsible for regulating the entry of CO2, necessary for photosynthesis, through the stomata. When there is sufficient light and optimal temperature, the guard cells absorb water and become turgid, opening the stomata. Through the open stomata, the CO2 enters the plant to reach the chloroplasts, where photosynthesis takes place.
Transpiration, the process of water loss through the stomata, is another significant function of guard cells. The opening and closing of stomata by the guard cells regulate the rate of transpiration. In response to dry conditions, the guard cells become flaccid, closing the stomata to conserve the water in the plant. Conversely, when the conditions are humid, and the plant has enough water, the guard cells absorb water and cause the stomata to open, allowing for transpiration.
Guard cells respond to various stimuli, including light, temperature, and hormones, to control the opening and closing of the stomata. Light energy absorbed by the chloroplasts signals the guard cells to open the stomata and initiate photosynthesis. Additionally, hormones, such as abscisic acid (ABA), influence the opening and closing of stomata in response to water availability.
In conclusion, guard cells play an integral role in the survival and growth of plants by regulating the opening and closing of stomata to control the rate of gas exchange, photosynthesis, and transpiration. Understanding the physiology and function of these crucial cells advances our knowledge of plant biology and helps us develop sustainable practices to improve crop production and mitigate the effects of climate change.