Yes, stomata have vacuoles, but their number and size change depending on whether the stomata are open or closed.
Vacuole Dynamics in Stomata
Stomatal guard cells, which control the opening and closing of stomata, contain vacuoles that play a crucial role in this process. The vacuoles' dynamic nature is key to stomatal function.
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Open Stomata: In open stomata, a single, large vacuole occupies a significant portion of the guard cell's volume. This large central vacuole contributes to the turgor pressure needed to keep the stomata open. [Source: Reference mentioning the large vacuole in open stomata (11-May-2023)]
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Closed Stomata: When the stomata close, this large vacuole fragments into several smaller, interconnected vesicles. This fragmentation is a part of the mechanism that reduces turgor pressure and causes the stomata to close. [Source: Reference mentioning vacuole fragmentation in closed stomata (11-May-2023)]
Several studies highlight the importance of vacuolar dynamics in stomatal movement:
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Ion Transport: Ions are transported across the vacuolar membrane (tonoplast) via channels and active transporters. Vacuolar proton pumps are also involved in this process. [Source: References describing ion transport across the tonoplast (PMC5462060, 24733919)]
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Turgor Regulation: Changes in vacuolar volume directly influence the turgor pressure within the guard cells, affecting stomatal opening and closing. [Source: References linking vacuolar volume changes to stomatal movement (16244153, 24733919)]
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K+/H+ Exchangers: The tonoplast-localized K+/H+ exchangers NHX1 and NHX2 are crucial for vacuolar K+ uptake, turgor regulation, and stomatal function. [Source: Reference emphasizing the role of NHX1 and NHX2 in stomatal function (10.1105/tpc.111.095273)]
The vacuole's role is not simply about storing water; it’s actively involved in regulating the movement of ions and water, leading to changes in turgor pressure that ultimately control stomatal aperture. [Source: Multiple references discussing the role of vacuoles in stomatal regulation]
