Resource Acquisi3on and Transfer in Vascular Plants · Resource Acquisi3on and Transfer in Vascular...
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1 Chapter 36 Resource Acquisi3on and Transfer in Vascular Plants BIOL 223 H 2 O H 2 O and minerals • Plants have evolved to… • Gather and conserve resources • Transport them • Water, minerals, and sugars • Via diffusion, ac3ve transport, and bulk flow Fig. 36-2-2 H 2 O H 2 O and minerals CO 2 O 2 O 2 CO 2
Transcript of Resource Acquisi3on and Transfer in Vascular Plants · Resource Acquisi3on and Transfer in Vascular...
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Chapter36
ResourceAcquisi3onandTransferinVascularPlants
BIOL223
H2O
H2O and minerals
• Plantshaveevolvedto…
• Gatherandconserveresources
• Transportthem
• Water,minerals,
andsugars
• Viadiffusion,ac3vetransport,andbulk
flow
Fig.36-2-2
H2O
H2O and minerals
CO2 O2
O2
CO2
2
Fig.36-2-3
H2O
H2O and minerals
CO2 O2
O2
CO2
Sugar Light
ShootArchitectureandLightCapture
• Stems
• conduitsforwaterandnutrients
• suppor3ngstructuresforleaves
• Phyllotaxy
• Arrangementofleavesonastem
• Speciesspecific
Fig.36-3
Buds
Shoot apical meristem
42 29 16
24 32 40
34 21
8 3 11 19
27 6
26 13 14
5 1
18 9
31 10 2 4
23 15 7 12 17
28 20 25
1 mm
22
3
• Lightabsorp3onaffectedby
• Leafareaindex
• Ra3ooftotalupperleafsurfaceareaofaplant
• dividedbythesurfaceareaoflanditcovers
• Plantsself-pruneunnecessaryleaves
• Leaforienta3on
• Horizontal-typical
• Ver3cal-grasses
ShootArchitectureandLightCapture
Fig.36-4
Ground area covered by plant
Plant A Leaf area = 40% of ground area
(leaf area index = 0.4)
Plant B Leaf area = 80% of ground area
(leaf area index = 0.8)
RootArchitecture• Soil
• resourceminedbytherootsystem
• Taprootsystems
• anchorplants
• characteris3cofangiosperms
• Earlyingrowth,thenoVenreplacedbyfibrous
• Mycorrhizae
• Symbiosisbetweenrootsandhyphaeofsoilfungi
• helpedplantscolonizeland
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TransportViaDiffusion,Ac3veTransport,BulkFlow
• Transport
• Beginswiththeabsorp3onofresourcesbyplantcells
• Regulatedbyselec3vepermeability
DiffusionandAc3veTransportofSolutes
• Diffusion
• Passive
• Pumpingsolutes
• Ac3veandrequiresenergy
• passthroughtransport
proteins
• embeddedinthecell
membrane
• Protonpump
• Mostimportanttransportprotein
• Createahydrogeniongradient
• Formofpoten3alenergy
• canbeharnessedtodowork
• Contributetomembranepoten9al
DiffusionandAc3veTransportofSolutes
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CYTOPLASM EXTRACELLULAR FLUID
K+
K+
K+
K+ K+
K+
K+
Transport protein
_ _
_
_
+
_
+
+
+
+
(a) Membrane potential and cation uptake
NO3−
NO3−
NO 3− NO
3 −
NO3−
NO3−
H+
H+
H+
H+
H+
H+ H+
H+ H+
H+ H+
H+
(b) Cotransport of an anion with H+
H+
_
_
_
_
_
_
+
+
+
+
+
+
H+ H+ H+
H+ H+
H+
H+ H+
H+
H+
H+ H+
_
_
_
_
_
_
+
+
+
+
+
+
(c) Cotransport of a neutral solute with H+
S
S S
S
S
S
• Plantcells
• useenergyinproton
gradient
• andmembranepoten3al
• todrivethe
transportofmany
differentsolutes
DiffusionandAc3veTransportofSolutes
DiffusionofWater(Osmosis)• Plants
• Mustbalancewateruptakeandloss
• Osmosis
• Determinesnetwateruptakeorloss
• affectedbysoluteconcentra3onandpressure
• Waterpoten9al
• combineseffectsofsoluteconcentra3onandphysicalpressure
• determinesthedirec3onofwatermovement
• AbbreviatedasΨ(psi)
• Measuredinmegapascals(MPa)
• Ψforpurewateratsealevelandroomtemperature=0Mpa
• Waterflowsfromregionsofhigherwaterpoten3al
• toregionsoflowerwaterpoten3al
DiffusionofWater(Osmosis)
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HowSolutesandPressureAffectWaterPoten3al• Bothpressureandsoluteconcentra3onaffectwaterpoten3al
• Solutepoten9al(ΨS)
• propor3onaltothenumberofdissolvedmolecules
• Alsocalledosmo9cpoten9al
• Pressurepoten9al(ΨP)
• Physicalpressureonasolu3on
• Turgorpressure
• Pressureexertedbytheplasmamembraneagainstthecellwall
• andthecellwallbackagainsttheprotoplast
WaterPoten3al
Fig.36-8
(a) (b) (c) (d) 0.1 M solution
Positive pressure Increased
positive pressure
Negative pressure (tension)
Pure water
H2O H2O
H2O H2O
ψP = 0 ψS = 0
ψP = 0 ψS = −0.23
ψP = 0 ψS = 0
ψP = 0 ψS = 0
ψP = −0.30 ψS = 0
ψP = 0.23 ψS = −0.23
ψP = 0.30 ψS = −0.23
ψP = 0 ψS = −0.23
ψ = 0 MPa
ψ = 0 MPa
ψ = 0 MPa
ψ = 0 MPa
= −0.23 MPa
ψ = 0.07 MPa
ψ = −0.30 MPa
ψ = −0.23 MPa
ψ
= solute potential
= pressure potential
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Fig.36-9
ψP = 0 ψS = −0.7
ψP = 0 ψS = −0.9
ψP = 0 ψS = 0 ψ = −0.9 MPa
ψ = −0.7 MPa
ψ = 0 MPa
(a) Initial conditions: cellular ψ > environmental ψ (b) Initial conditions: cellular ψ < environmental ψ
0.4 M sucrose solution:
Initial flaccid cell:
Pure water:
ψ = 0 MPa
ψP = 0.7 ψS = −0.7
Turgid cell Plasmolyzed cell ψP = 0 ψS = −0.9 ψ = −0.9 MPa
Plasmolysis
Facilita3ngDiffusionofWater
• Aquaporins
• Transportproteins
• Allowthepassageofwater
• Rateofwatermovement
• Regulatedbyphosphoryla3onofthe
aquaporinproteins
ThreeMajorPathwaysofTransport
• Transport
• Alsoregulatedbythecompartmentalstructureofplantcells
• Plasmamembrane
• Directlycontrolsthetrafficofmolecules
• intoandoutoftheprotoplast
• Barrierbetweentwomajorcompartments
1. cellwall
2. cytosol/cytoplasm
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3.Centralvacuole
• Thirdmajorcompartment
• Vacuolarmembrane
• regulatestransportbetweenthecytosolandthevacuole
ThreeMajorPathwaysofTransport
