Abscisic acid signaling pathway | ABA mediated stomatal opening and closure
Summary
TLDRThe video script delves into the role of abscisic acid in regulating stomatal movement in plants. Stomata, crucial for gas exchange, open during the day for carbon dioxide intake and close at night to conserve water, influenced by abscisic acid. Guard cells control this process, swelling with water during the day to open stomata and losing water at night due to abscisic acid, leading to closure. The script explains the cellular mechanisms involving ion channels, the proton pump, and the impact of sunlight on these processes, highlighting the dynamic balance between environmental cues and plant physiology.
Takeaways
- 🌿 Stomata are crucial structures in plant leaves that regulate gas and water exchange with the environment.
- 🌞 Abscisic acid (ABA) plays a significant role in controlling stomatal opening and closing, which is essential for plant water conservation.
- 💧 During the day, stomata open to allow carbon dioxide and water intake, and ABA is not present, facilitating this process.
- 🌑 At night or in hot conditions, ABA is secreted, leading to stomatal closure to prevent water loss through evaporation.
- 🔬 Guard cells, with their unique structure, are responsible for the movement of ions and water that control stomatal aperture.
- 💧 The opening of stomata involves the influx of water into guard cells, causing them to swell and the stomata to dilate.
- 🌡️ ABA binds to its receptor on guard cells, initiating a signaling cascade that leads to water loss from the guard cells and stomatal closure.
- 🔄 Ion channels, including potassium and chloride channels, are integral to the movement of ions that regulate guard cell turgor and, consequently, stomatal movement.
- 🌱 The proton pump in guard cells contributes to creating an osmotic imbalance that drives water movement into or out of the guard cells.
- 🌅 Blue light during the day activates the proton pump, leading to the production of ATP and the influx of potassium and sugars into guard cells, promoting stomatal opening.
Q & A
What is the primary function of stomata in plant leaves?
-Stomata in plant leaves are crucial for regulating the intake of carbon dioxide, oxygen, and water from the environment by the plants.
How does abscisic acid influence stomatal opening and closing?
-Abscisic acid plays a significant role in stomatal regulation. It triggers closure during conditions like high temperatures to prevent water evaporation, while stomata open in the presence of sunlight without the influence of abscisic acid.
What are guard cells, and how are they related to stomata?
-Guard cells are specialized cells surrounding the stomatal pore. They regulate the opening and closing of stomata by swelling or shrinking, which is influenced by the presence of abscisic acid.
What happens to the guard cells when abscisic acid is secreted?
-When abscisic acid is secreted, it binds to the abscisic acid receptor, leading to cell signaling processes that cause the guard cells to lose water, become flaccid, and ultimately close the stomata.
What are the roles of vacuoles and endoplasmic reticulum in stomatal regulation?
-Vacuoles, particularly the storage vacuoles in guard cells, and the endoplasmic reticulum are important for ion storage and regulation, which are crucial for the movement of ions and water that control stomatal opening and closing.
How do ion channels contribute to the stomatal movement?
-Ion channels, including potassium and calcium channels in the guard cell membrane and vacuole membrane, as well as chloride ion channels, facilitate the movement of ions in and out of the guard cells, which affects the turgor pressure and thus the opening and closing of stomata.
What is the role of the proton pump in guard cells?
-The proton pump in guard cells helps maintain the osmotic balance by pumping protons (H+) out of the cell. It also contributes to ATP synthesis, which is important for the energy required during stomatal movement.
How does the presence of sunlight affect stomatal opening?
-Sunlight, particularly the blue wavelength, activates the proton pump, leading to an osmotic imbalance that causes potassium and sugars to flow into the guard cells. This influx of solutes draws water into the guard cells, causing them to swell and open the stomata.
What is the significance of the calcium influx in guard cells?
-Calcium influx in guard cells, triggered by the binding of abscisic acid to its receptor, leads to the deactivation of potassium influx carriers and the activation of chloride export channels, resulting in the loss of water and closure of stomata.
Can you explain the role of reactive oxygen species (ROS) in stomatal regulation?
-Reactive oxygen species, such as H2O2, are activated by the abscisic acid receptor and contribute to the calcium influx, which further drives the stomatal closure process by affecting ion channels and pumps.
How does the absence of abscisic acid during the daytime lead to stomatal opening?
-In the absence of abscisic acid during the daytime, the proton pump is activated by sunlight, leading to the influx of potassium and sugars into the guard cells. This creates an osmotic imbalance that draws water into the guard cells, causing them to swell and open the stomata.
Outlines
🌿 Regulation of Stomatal Movement by Abscisic Acid
This paragraph explains the crucial role of abscisic acid in regulating stomatal opening and closure in plant leaves. Stomata are essential for plants to intake carbon dioxide, oxygen, and water. During daytime, stomata open to allow gas exchange, but they must close during hot temperatures to prevent water loss. Guard cells, which consist of two cells surrounding a pore, control stomatal movement. Abscisic acid, secreted in the absence of sunlight, binds to its receptor and triggers a signaling cascade that leads to the loss of water from guard cells, causing them to shrink and stomata to close. The paragraph also discusses the involvement of vacuoles, endoplasmic reticulum, ion channels, and the proton pump in this process.
🌞 Stomatal Response to Abscisic Acid and Sunlight
This paragraph delves into how abscisic acid and sunlight influence stomatal movement. In the presence of abscisic acid, stomata close due to the loss of water from guard cells, leading to a reduction in cell turgor and stomatal constriction. Conversely, during sunlight, blue light activates the proton pump, promoting the influx of potassium and sugars into guard cells, which increases cell turgor and opens the stomata. The paragraph highlights the osmotic imbalances created by ion movements and the subsequent water transport that drives stomatal opening and closure. The summary underscores the dual role of abscisic acid in stomatal regulation, closing stomata at night and allowing them to open during the day in the absence of the hormone.
Mindmap
Keywords
💡Abscisic Acid
💡Stomata
💡Guard Cells
💡Water Transport
💡Ion Channels
💡Calcium Influx
💡Reactive Oxygen Species (ROS)
💡Proton Pump
💡Osmotic Imbalance
💡ATP Synthase
Highlights
Stomata are crucial structures in plant leaves that regulate gas and water exchange.
Abscisic acid plays a key role in controlling the opening and closing of stomata.
During daytime, stomata need to open for CO2 and water intake, but must close during hot temperatures to prevent water loss.
In the presence of sunlight, stomata open without the influence of abscisic acid.
Guard cells regulate stomatal movement, swelling when water flows in and shrinking when it flows out.
Abscisic acid binds to its receptor, initiating a series of cell signaling processes.
The release of abscisic acid leads to guard cell water loss and stomatal closure.
Vacuoles and endoplasmic reticulum within guard cells are important for calcium storage.
Ion channels, including potassium and calcium channels, are involved in the regulation of stomatal movement.
The proton pump in the guard cell membrane helps maintain osmotic balance.
Abscisic acid receptor activation leads to the production of inositol trisphosphate (IP3), which triggers calcium release from vacuoles.
Reactive oxygen species (ROS), such as H2O2, contribute to calcium influx in guard cells.
High calcium concentration deactivates potassium influx carriers and activates chloride export channels.
The proton pump is inhibited by calcium, leading to an acidic internal environment in guard cells.
Osmotic imbalance due to ion movement causes water to move out of guard cells, leading to stomatal closure.
In the absence of abscisic acid and presence of sunlight, blue light activates the proton pump, promoting stomatal opening.
ATP hydrolysis and potassium influx are activated by the proton pump during daytime, contributing to stomatal opening.
Sugars produced during photosynthesis also contribute to the osmotic pressure that opens stomata.
Stomata close at night due to abscisic acid and open during the day in its absence, balancing water loss and gas exchange.
Transcripts
okay now let's look into the matter of
how abscisic acid regulates the stomatal
opening and clogging stomata is a very
important structure in the plant leaves
that regulates
the intake of carbon dioxide oxygen and
water from the environment by the plants
and abscisic acid play a very important
role in terms of opening and closing the
stomata plants need to open the stomata
during day time in order to get the
carbon dioxide and water and also plant
need to prevent the stomatal opening
during very very hot temperatures to
prevent the water evaporation
so here we will see that in the presence
of
sunlight the stomata must open and in
presence of sunlight there is no role of
abscisic acid no presence of abscisic
acid as a result the stomata
will be opened the stomatal opening and
closure are regulated by known as the
guard cells two guard cells and one
simple pore in the center as you can see
in this picture
and this guard cell will get a rush of
water during the daytime during daytime
water start to flow inside of this guard
cell make this guard cell
really really target as a result of
which the stomata gets opened but when
there is no sunlight
then there is secretion of abscisic acid
and as a result of release of abscisic
acid the abscisic acid binds to the
abscisic acid receptor and due to some
cell signaling processes
ultimately this guard cell loses water
and as a result the guard cells will
become flashy and the stomata will close
up so let's see how exactly this
abscisic acid regulates the stomatal
opening and closure
and this stomatal opening closure there
are different components important one
of such component is the vacuole and
endoplasmic reticulum that are present
inside the cells particularly here the
specific
calcium stored storage vacuoles of the
guard cells are important
apart from them there are different ion
channels like positive ion channels of
potassium channel and calcium channel
both are present
in the membrane of the guard cell as
well as in the vacuole membrane
and then chloride ion channels that are
present again in the back pole as well
as in the guard cell membrane
apart from that there is a proton pump
present in the guard cell membrane that
usually pumps proton h plus from the
guard cell outside of the cell
and this potassium transporters are of
two types in flux as well as efflux
influx takes potassium inside if flux
takes potassium outside but the chloride
channels that we find in the surface of
the guard cell membrane are export
channels only
and the most important thing is the
abscisic acid receptor that is found on
the surface of this guard cell and the
signaling begins when there is a ligand
in this case the abscisic acid act as a
ligand will bind to the abscisic acid
receptor or abar and due to this
interaction there is a cell membrane
associated component known as
phospholipid c and produces inositol
tris phosphate ip3 this ip3 can easily
go and interact with the calcium
channels in the vacuole and allow the
calcium to be transported from black
hole into the guard cell cytosol as a
result what we see is a calcium influx
this is the primary calcium influx
this abscisic acid receptor once
activated also activate reactive
reactive oxygen species or ros this
reactive oxygen species example is h2o2
simply this reactive oxygen species also
causes the calcium influx channels to
drive more calcium ions inside this
guard cell
so what happen is a secondary calcium
influx so both this calcium influx
causes high calcium concentration inside
the guard cell this high calcium
concentration have two different
consequences these calciums will go and
interact to the potassium influx
carriers and what it does is
deactivating the potassium influx
carrier as a result potassium ions
cannot be transported inside of the
guard cell
this calcium ions also move and interact
with the chloride export channels and
they allow chlorides cl minus to be in
exported out of the guard cell
outside
this calcium also interacts with the
proton pump and inhibits the function of
the proton pump as a result the proton
cannot be pumped out so there is a high
concentration of h plus building up in
the guard cell making the guard cell
inside ambience acidic and outside
alkaline
and as a result of this high
concentration of chloride
potassium efflux channels or exporters
are activated which will start taking up
potassium outside to compensate this
balance of potassium outflow potassium
and chlorides start to transport via
calcium and chloride both start to
transport from vapor into the guard cell
cytoplasm
see
they start moving outside into the guard
cell cytoplasm
now the more calcium influx is done the
more chloride is transported to the
cytoplasm of guard cell the more they
are transported out the more they are
transported out via potassium channel
via chloride channel so ultimately what
we see is a movement of potassium and
chlorides rapidly from the guard cell
outside and as a result of this outside
movement of positively and negatively
charged ions there is an osmotic
imbalance created and to tackle this
osmotic imbalance the only way is the
movement of water from
the low solute concentration to the high
solute concentration and in this case
the high solute concentration is
surrounding of the guard cell so water
will move from the guard cell outside
via specific water transporter channels
in the gut cell which are not shown in
this picture
this is what happens when there is
presence of abscisic acid and as a
result of this net water movement
outside
the
guard cells become really flashy and as
a result of which the guard cells
overall opening becomes constricted and
stomata gets closed
now let's look at another situation when
there is sunlight
when there is sunlight
the sun provides the blue light
particularly the blue wavelength of the
light interacts to the for proton pump
and activates the proton pump so start
to attach with atp synthase activity
because the proton pump has a atp
synthesis activity
atp gets hydrolyzed into adp and pi as a
result the proton pump start
to
transfer protons from the guard cell
outside and as a result of this proton
movement outside there is a osmotic
imbalance start to be created and soon
this potassium
influx carriers also activated potassium
start to flow inside so potassium start
flowing inside as the potassium start to
rush flowing inside and we know during
day time the plants start producing
their food so food means glucose and
sucrose and other sugars are produced
the sugars will also start their journey
to move inside this guard cell via the
sugar transporter the sugar can migrate
on its own by the sugar transporters or
the sugar can migrate along with a
proton inside of the guard cell with a
co-transport model in both the way there
is a high flow of proton sugar as well
as potassium inside the guard cell in
presence of blue light that means in the
daytime as a result of which
again there is an osmotic imbalance more
electrolytes sugar inside the guard cell
than outside so as a result water which
is present surrounding the guard cell
start to rush in via water channels
inside the guard cell and as a result of
which what will happen as water rushes
in this guard cell will become
hugely turgid as a result of this high
turgidity of the guard cell they open up
the stomata and this is how the stomatal
opening is done in the absence of
abscisic acid in the daytime so for
summary in the abscisic acid when it's
present the stomata will be closed when
there is no abscisic acid the stomata
will be open the abscisic acid closes
the stomata during night time and
without abscessing acid during daytime
stomata opens up
Посмотреть больше похожих видео
PLANT HORMONES - Auxin Gibberellin Cytokinin Ethylene Abscisic Acid
What are stomata and what's their function?
Gas Exchange in Plants | Biology | Secondary
GCSE Biology - Structure of a Leaf and Stomata #50
Xylem and Phloem - Part 2 - Transpiration - Transport in Plants | Biology | FuseSchool
Types of Photosynthesis in Plants: C3, C4, and CAM
5.0 / 5 (0 votes)