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

Les plantes ont besoin d&#x27;un &#xE9;chantillon de dioxyde de carbonedepuis l&#x27;atmosph&#xE8;re &#xE0; la photosynth&#xE8;se. 
Les surfaces des feuilles des plantes contiennent des ouverturesqui facilitent l&#x27;&#xE9;change de gaz. 
Ces ouvertures sont appel&#xE9;es stomates. 
La lumi&#xE8;re du soleil d&#xE9;clenche l&#x27;ouverture des stomates,permettant au dioxyde de carbone de p&#xE9;n&#xE9;trer dans la feuille lorsqu&#x27;elleest n&#xE9;cessaire &#xE0; la photosynth&#xE8;se. 
L&#x27;oxyg&#xE8;ne est un sous-produit de la photosynth&#xE8;seet s&#x27;&#xE9;chappe dans l&#x27;atmosph&#xE8;re par les stomates. 
Une paire de cellules de garde r&#xE9;gule l&#x27;ouverture de chaque stomate. 
Ces cellules sp&#xE9;cialis&#xE9;es se gonflent lorsqu&#x27;ellesabsorbent l&#x27;eau des cellules voisines par osmose,cr&#xE9;ant une ouverture qui permet l&#x27;&#xE9;change de gaz. 
Quand l&#x27;eau quitte les cellules de garde,ils r&#xE9;tr&#xE9;cissent et la stomie se referme. 
La concentration d&#x27;ions influence la quantit&#xE9;d&#x27;eau dans les cellules de garde. 
La lumi&#xE8;re du soleil stimule les cellules de garde pour qu&#x27;elles absorbent les ions de potassium. 
L&#x27;augmentation de la concentration de potassiumfait entrer de l&#x27;eau dans les cellules, ouvrant ainsi la stomie. 
Quand le potassium quitte les cellules de garde,l&#x27;eau suit par osmose. 
Les cellules de garde, maintenant flasques, ferment la stomie. 
Pendant que les stomates sont ouvertes, elles facilitent l&#x27;&#xE9;change de gaz,elles permettent &#xE9;galement &#xE0; l&#x27;eau de s&#x27;&#xE9;chapper des feuillespar &#xE9;vaporation. 
L&#x27;eau d&#x27;&#xE9;vaporation par perte ou transpiration permetle mouvement &#xE0; longue distance de l&#x27;eau &#xE0; travers la plante. 
La transpiration est typiquement la plus grandeles jours chauds et ensoleill&#xE9;s. 
Cependant, si une plante ne peut pas obtenir suffisamment d&#x27;eau,ses stomates se fermeront rapidement pour &#xE9;viter le fl&#xE9;trissement. 
Il est int&#xE9;ressant de noter que m&#xEA;me si elle est gard&#xE9;e dans l&#x27;obscurit&#xE9;,les plantes s&#x27;ouvrent et se ferment les stomatessur un cycle r&#xE9;gulier de 24 heures, gr&#xE2;ce &#xE0; une horloge interne. 
L&#x27;ouverture et la fermeture des stomatessont &#xE9;troitement r&#xE9;glement&#xE9;s, les plantes font toutpour r&#xE9;pondre &#xE0; des conditions environnementales sp&#xE9;cifiques. 
Dans leur fonction de gardiens,Les stomates &#xE9;quilibrent efficacement l&#x27;&#xE9;change gazeux et la transpiration.

Daszkowska-Golec, Agata et Iwona Szarejko. « Ouvrir ou fermer la porte - Action des stomates sous le contrôle des phytohormones dans des conditions de stress hydrique. » Frontiers in Plant Science 4 (2013). [<a href="https://doi.org/10.3389/fpls.2013.00138 » target="_blank">Source</a>]

Inoue, Shin-ichiro et Toshinori Kinoshita. « Régulation par la lumière bleue de l’ouverture stomatique et de la membrane plasmique H+-ATPase1[OPEN]. » Physiologie végétale 174, n° 2 (juin 2017) : 531-38. [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5462062/ » target="_blank">Source</a>].

régulation de la transpiration par les stomates

Pendant la photosynth&#xE8;se, les plantes acqui&#xE8;rent le dioxyde de carbone n&#xE9;cessaire et lib&#xE8;rent l&#x2019;oxyg&#xE8;ne produit dans l&#x2019;atmosph&#xE8;re. Les ouvertures dans l&#x2019;&#xE9;piderme des feuilles v&#xE9;g&#xE9;tales sont le site de cet &#xE9;change de gaz. Un seul orifice s&#x2018;appelle un stomate, d&#xE9;riv&#xE9; du mot grec pour &#x201C; bouche &#x201D;. Les stomates s&#x27;ouvrent et se ferment en r&#xE9;ponse &#xE0; une vari&#xE9;t&#xE9; d&#x27;indices environnementaux.
 
 Chaque stomate est entour&#xE9; de deux cellules de garde sp&#xE9;cialis&#xE9;es qui cr&#xE9;ent une ouverture lorsque ces cellules absorbent de l&#x2019;eau. Le transport des ions r&#xE9;gule la quantit&#xE9; d&#x2019;eau dans les cellules de garde. Lors du d&#xE9;clenchement, les pompes transf&#xE8;rent les ions hydrog&#xE8;ne hors de la cellule de garde. Cette hyperpolarisation de la membrane provoque l&#x2019;ouverture des canaux de potassium tensiod&#xE9;pendants et permet aux solut&#xE9;s, tels que les ions potassium et le saccharose, d&#x2019;entrer dans les cellules de garde. L&#x2019;augmentation de la concentration de solut&#xE9;s conduit l&#x2019;eau dans les cellules de garde, qui s&#x2019;accumule dans la vacuole. En cons&#xE9;quence, les cellules de garde se courbent et se d&#xE9;forment &#xE0; la fa&#xE7;on d&#x2019;un rein, cr&#xE9;ant ainsi l&#x27;ouverture du stomate. Lorsque les solut&#xE9;s quittent les cellules de garde, l&#x2019;eau suit, ce qui entra&#xEE;ne un r&#xE9;tr&#xE9;cissement des cellules de garde et la fermeture de l&#x2019;orifice.
 
 Une vari&#xE9;t&#xE9; de signaux environnementaux et internes d&#xE9;clenche l&#x2019;ouverture des stomates. Par exemple, la lumi&#xE8;re bleue active les r&#xE9;cepteurs sensibles &#xE0; la lumi&#xE8;re sur la surface cellulaire qui d&#xE9;clenchent une cascade mol&#xE9;culaire conduisant &#xE0; l&#x2019;ouverture des stomates. En outre, lorsque la concentration de dioxyde de carbone tombe dans le tissu foliaire, l&#x2019;ouverture des stomates est d&#xE9;clench&#xE9;e afin que les cellules puissent acc&#xE9;der &#xE0; ce r&#xE9;actif essentiel de la photosynth&#xE8;se.
 
 La perte de vapeur d&#x2019;eau est essentielle pour l&#x2019;&#xE9;tablissement d&#x2019;une traction de transpiration : l&#x2019;eau s&#x2019;&#xE9;vapore &#xE0; la surface des cellules m&#xE9;sophylles et s&#x2019;&#xE9;chappe dans l&#x2019;atmosph&#xE8;re par des stomates ouverts. La perte d&#x2019;eau cr&#xE9;e une traction de transpiration qui tire l&#x2019;eau suppl&#xE9;mentaire du sol dans les racines et jusqu&#x2019;au bout des feuilles.
 
 Lorsque la quantit&#xE9; d&#x27;eau disponible est insuffisante, comme dans des conditions de s&#xE9;cheresse, les stomates se ferment. L&#x27;hormone acide abscissique (ABA) joue un r&#xF4;le important au cours de ce processus, en se liant aux r&#xE9;cepteurs des membranes des cellules de garde et en augmentant la concentration de solut&#xE9;s intracellulaires. L&#x27;ABA joue &#xE9;galement un r&#xF4;le important dans le contr&#xF4;le circadien de l&#x27;ouverture des stomates, en provoquant l&#x27;ouverture d&#x27;un plus grand nombre de stomates &#xE0; la lumi&#xE8;re du jour et leur fermeture dans l&#x27;obscurit&#xE9;.

Régulation de la transpiration par les stomates

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

Enseignement

JoVE Core

Biology

Biologie

Plant Biology

Biologie végétale

Plant Structure, Growth and Function

Structure, croissance et nutrition des plantes

KEY TERMS AND CONCEPTS

TERMES ET CONCEPTS CLÉS

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

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regulation of transpiration by 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...

adaptations that reduce water loss

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the roles of bacteria and fungi in plant nutrition

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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

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Georgia Standards of Excellence

9-12

Botany

SBO1.

Transport

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How Guard Cells Open Plant Stomata

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