Name: how guard cells open plant stomata
Uploaded: 2026-08-26T08:19:56.906Z
Duration: 2 min 19 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Life Science

SC.912.L.14

SC.912.L.14.7

Regulation of Transpiration by Stomata

Plants need enough carbon dioxide from the atmosphere to carry out photosynthesis. The surfaces of plant leaves contain openings that help with gas exchange. These openings are called stomata.Sunlight is one of the primary signals that promote stomatal opening. This allows carbon dioxide to enter the leaf when it is needed for photosynthesis. Oxygen is a byproduct of photosynthesis and escapes into the atmosphere through the stomata.A pair of guard cells controls each stomatal opening. These specialized cells swell when they take in water from neighboring cells by osmosis. This creates an opening that allows gas exchange. When water leaves the guard cells, they shrink and the stoma closes.The concentration of ions affects the amount of water in the guard cells. Sunlight stimulates guard cells to take up potassium ions. The increase in potassium concentration drives water into the cells, opening the stoma.When potassium leaves the guard cells, water follows by osmosis. The now-flaccid guard cells close the stoma.Open stomata help with gas exchange, but they also allow water to escape from leaves through evaporation. This evaporative water loss, or transpiration, allows water to move long distances through the plant.Transpiration is usually greatest on warm, sunny days. However, if a plant cannot get enough water, its stomata close quickly to prevent wilting.Interestingly, even when kept in the dark, many plants open and close their stomata in a roughly 24-hour rhythm because of an internal clock.The opening and closing of stomata are tightly controlled, allowing plants to respond to specific environmental conditions. As gatekeepers, stomata efficiently balance gas exchange and transpiration.

regulation of transpiration by stomata

During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of plant leaves is the site of this exchange of gasses. A single opening is called a stoma&#x2014;derived from the Greek word for &#x201C;mouth.&#x201D; Stomata open and close in response to a variety of environmental cues.Each stoma is flanked by two specialized guard cells that create an opening when these cells take up water. The transport of ions regulates the amount of water in guard cells. When trigger, pumps translocate hydrogen ions out of the guard cell. This hyperpolarization of the membrane causes voltage-gated potassium channels to open and allow solutes, such as potassium ions and sucrose, to enter the guard cells. The increased concentration of solutes drives water into the guard cells, which accumulates in the vacuole. As a result, the guard cells bow and deform into a kidney shape, creating the stoma opening. When solutes leave guard cells, water follows, resulting in guard cell shrinkage, and closure of the opening.A variety of environmental and internal signals triggers stomata opening. For example, blue light activates light-sensitive receptors on the cell surface that initiate a molecular cascade leading to stomata opening. In addition, when the concentration of carbon dioxide falls within the leaf tissue, stomata opening is induced so cells can access this critical reactant of photosynthesis.Loss of water vapor is critical for the establishment of transpirational pull: water evaporates on the surface of mesophyll cells and escapes into the atmosphere through open stomata. The water loss creates a transpirational pull that pulls additional water from the soil into the roots and all the way into the leaves.When sufficient water is not available, as in conditions of drought, stomata close. The hormone abscisic acid (ABA) is important in this process, binding to receptors on guard cell membranes and increasing intracellular solute concentration. ABA is also important in circadian control of stomatal opening, causing more stomata to be open in daylight, and closed in the dark.

During photosynthesis, plants acquire the necessary carbon dioxide and release the produced oxygen back into the atmosphere. Openings in the epidermis of ...

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Education

JoVE Core

Biology

Plant Biology

Plant Structure, Growth and Function

KEY TERMS AND CONCEPTS

how guard cells open plant stomata

How guard cells open and close plant stomata controls gas exchange in leaves. A stoma is a tiny opening in the leaf epidermis. The word comes from the Greek word for “mouth.” These openings let plants take in carbon dioxide for photosynthesis and release oxygen into the air.

Each stoma is surrounded by two guard cells. When these cells take up water, they create an opening. Ion transport controls how much water stays in the guard cells. A trigger causes pumps to move hydrogen ions out of the guard cell. This changes the membrane voltage and opens voltage-gated potassium channels. Potassium ions and sucrose then enter the guard cells. As solute levels rise, water moves in and collects in the vacuole. The guard cells swell, bend, and take on a kidney shape, which opens the stoma.

Stomata also close when solutes leave the guard cells. Water follows the solutes out, so the guard cells shrink and the opening closes. Blue light can start this process of opening. Light-sensitive receptors on the cell surface begin a molecular cascade. Low carbon dioxide inside the leaf can also trigger opening so cells can keep using this key photosynthesis reactant.

Water loss through open stomata helps create transpirational pull. Water evaporates from the surface of mesophyll cells and escapes into the atmosphere through the stomata. This pull draws more water from the soil, through the roots, and up into the leaves. When water is scarce, such as during drought, stomata close. The hormone abscisic acid, or ABA, helps drive this response by binding to receptors on guard cell membranes and increasing intracellular solute concentration. ABA also supports circadian control, so more stomata are open in daylight and closed in the dark.

How Guard Cells Open Plant Stomata

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xylem and transpiration-driven transport of resources

xylem-and-transpiration-driven-transport-of-resources

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How guard cells open and close plant stomata controls gas exchange in leaves. A stoma is a tiny opening in the leaf epidermis. The word comes from the Greek word for “mouth.” These openings let plants take in carbon dioxide for photosynthesis and release oxygen into the air. Each stoma is surrounded by two guard cells. When these cells take up water, they create an opening. Ion transport controls how much water stays in the guard cells. A trigger causes pumps to move hydrogen ions out of the...

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key terms and concepts

Explore how guard cells control stomata, gas exchange, and transpiration in leaves. Learn how light, CO2, and ABA affect opening and closing.

How Guard Cells Open Plant Stomata | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

Georgia Standards of Excellence

9-12

Botany

SBO1.

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How Guard Cells Open Plant Stomata

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