Cytokinin is the hormone that primarily opens stomata.
How Cytokinin Opens Stomata
Cytokinins are a class of plant hormones that play a crucial role in various physiological processes, including stomatal opening. While the exact mechanism is complex and involves interactions with other factors, cytokinins directly influence guard cell turgor pressure, the driving force behind stomatal opening. Increased cytokinin levels promote potassium ion uptake into guard cells, leading to increased water uptake and the subsequent swelling that opens the stomata.
- Increased Potassium Ion Uptake: Cytokinins stimulate the active transport of potassium ions (K+) into the guard cells.
- Increased Water Potential: The influx of potassium ions lowers the water potential inside the guard cells.
- Water Uptake by Osmosis: Water then moves into the guard cells via osmosis, increasing their turgor pressure.
- Stomatal Opening: This increased turgor pressure causes the guard cells to swell and the stomata to open.
Other Factors Affecting Stomata
It's important to note that stomatal opening is a complex process influenced by multiple factors besides cytokinin. Environmental conditions such as light intensity, carbon dioxide levels, and water availability also play significant roles. Cytokinin's role is to regulate the process in concert with these other signals.
Further Information on Cytokinin
Cytokinins have many other roles in plant biology beyond stomatal regulation. They are involved in:
- Plant Growth: Promoting cell division and differentiation.
- Cytokinesis: The process of cell division.
- Disease Resistance: Inducing resistance to certain plant pathogens.
There are approximately 2000 known natural and synthetic cytokinins.
