© 2014 Pearson Education, Inc. 1. Light H 2 O and minerals H2OH2O Sugar O2O2 CO 2 O2O2 2.

© 2014 Pearson Education, Inc. 1

© 2014 Pearson Education, Inc.

Light

H2Oandminerals

H2O Sugar

O2

CO2

O2CO2

2

© 2014 Pearson Education, Inc.

Shootapicalmeristem

Buds

3421

42 2916

11 1927

3224 40

28

15

10

2331

18

1326

22

1217

2520

1

2

3

4

5

6

7

8

9

14

1 mm

3

© 2014 Pearson Education, Inc.

Apoplastic route

Cell wall

Symplastic route

Transmembrane route

Cytosol

KeyPlasmodesma

Plasma membrane Apoplast

Symplast

4

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CYTOPLASM EXTRACELLULARFLUID

Protonpump

Hydrogen ion

Sucrose(neutral solute)

Potassium ion

Ion channel

Nitrate

(d) Ion channels(c) H and cotransport of ions

(b) H and cotransport of neutral solutes

(a) H and membrane potential

H/sucrosecotransporter

H/NO3−

cotransporter

S

NO3−

K

K

K

K

K K

K

H H

HH

H

H

H

H

H

H

H

H

S

S

S

S

S

H

H

H

H

H

H

H

H

H

H

H

H

HH

H

HH

H

NO3

−

NO3−

NO3−

NO3−

NO 3−

5

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Plasmolyzedcell at osmoticequilibriumwith itssurroundings

Turgid cellat osmoticequilibriumwith itssurroundings

0.4 M sucrosesolution:

(a) Initial conditions:cellular environmental

−0.9 MPa 0 MPa

Initial flaccid cell:

0 MPa

00

P

S

Pure water:

(b) Initial conditions:cellular environmental

−0.7 MPa

−0.7

P

S

−0.9

P

S

0

−0.9 MPa

−0.9

P

S

0

0

0.7

P

S−0.7

6

© 2014 Pearson Education, Inc.

Turgid

Wilted

7

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Technique

Control: Solutioncontaining all minerals

Experimental: Solutionwithout potassium

8

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© 2014 Pearson Education, Inc.

Nitrogen-deficient

Potassium-deficient

Phosphate-deficient

Healthy

10

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Soil particle K

Root hair

Cell wall

Mg2K

H

H

K

Ca2 Ca2

H2O CO2 H2CO3 HCO3−

11

© 2014 Pearson Education, Inc.

ATMOSPHERE

ATMOSPHERE

SOIL

SOIL

Nitrogen-fixingbacteria

N2

N2 N2

NH3

(ammonia)

H

(from soil)

Ammonifyingbacteria

Amino acids

NH4

(ammonium) NO2

−

(nitrite)Nitrifying bacteria

NO3−

(nitrate)Nitrifying bacteria

Denitrifyingbacteria

Microbialdecomposition

Nitrate andnitrogenous

organiccompoundsexported in

xylem to shoot system

NH4

Root

Proteins from humus(dead organic material)

12

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Roots

Nodules

13

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Epidermis Cortex

Epidermalcell

Endodermis

Mantle (fungal sheath)

Mantle (fungal sheath)

Fungalhyphaebetweencorticalcells (LM) 50 m

1.5 mm(C

olo

rize

d S

EM

)

Epidermis Cortex

Fungalvesicle

Endodermis

Cortical cell

Casparianstrip

Plasmamembrane

Arbuscules

(LM)

10

m

Roothair

Fungalhyphae

(a) Ectomycorrhizae

(b) Arbuscular mycorrhizae (endomycorrhizae)

14

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Experiment Results

Invaded Uninvaded Sterilizedinvaded

Sterilizeduninvaded

Soil type

Invaded UninvadedSoil type

White ash

Sugar maple

Seedlings

Red maple

Myc

orr

hiz

alco

lon

izat

ion

(%

)

Incr

ease

inp

lan

t b

iom

ass

(%) 300

200

100

0

30

20

10

0

40

15

© 2014 Pearson Education, Inc.

Staghorn fern, an epiphyte

16

© 2014 Pearson Education, Inc.

Parasitic plants

Mistletoe, a photosyntheticparasite

Dodder, a nonphoto-synthetic parasite(orange)

Indian pipe, a nonphoto-synthetic parasite ofmycorrhizae

17

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Carnivorous plants

Pitcher plants

Venus flytraps

Sundew

18

© 2014 Pearson Education, Inc.

Apoplasticroute

Symplasticroute

Transmembraneroute

The endodermis: controlled entryto the vascular cylinder (stele)

Apoplasticroute

Symplasticroute

Roothair

Plasmamembrane

Epidermis

Casparian strip

Vascularcylinder(stele)

Vessels(xylem)

Cortex

Endodermis

Pathway alongapoplast

Transport in the xylem

Casparian strip

Pathway throughsymplast

Endodermalcell

1

12

2

4

5

3

34

5

54

19

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Xylem

Microfibrils incell wall of

mesophyll cell

Microfibril (cross section)

Air-waterinterface

Waterfilm

Cuticle

Mesophyll

Cuticle Stoma

Air space

Upperepidermis

Lowerepidermis

20

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Cohesionby hydrogenbonding

Water molecule

Cohesionand adhesionin the xylem

Water uptake from soilWater

Soil particle

Root hair

Cell wall

Transpiration

Xylemcells

Water molecule

Adhesion by hydrogenbonding

Xylem sap

Mesophyll cells

Stoma

Atmosphere

Outside air

Wat

er p

ote

nti

al g

rad

ien

t

Leaf (air spaces)

Trunk xylem

Leaf (cell walls)

Trunk xylem

Soil

−7.0 MPa

−100.0 MPa

−1.0 MPa

−0.8 MPa

−0.6 MPa

−0.3 MPa21

© 2014 Pearson Education, Inc.

Guard cells turgid/Stoma open

K

Guard cells flaccid/Stoma closed

H2O

Radially orientedcellulose microfibrils

Cellwall

Vacuole

(a) Changes in guard cell shape and stomatal opening andclosing (surface view)

Guard cell

(b) Role of potassium ions (K) in stomatal opening and closing

H2O H2O

H2O

H2O

H2O

H2O

H2O

H2OH2O

22

© 2014 Pearson Education, Inc.

Old man cactus(Cephalocereussenilis)

Ocotillo(Fouquieriasplendens)

Oleander (Nerium oleander)

Thick cuticle Upper epidermal tissue

Stoma Lower epidermal tissue

CryptTrichomes(“hairs”)

100

m

23

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Apoplast

Symplast

Cell walls (apoplast)

Plasmodesmata

Mesophyll cell

Plasmamembrane

Companion(transfer) cell

Sieve-tubeelement

Mesophyllcell

Bundle-sheath cell

Phloemparenchyma cell

(a) Sucrose manufactured in mesophyll cellscan travel via the symplast (blue arrows)to sieve-tube elements.

(b) A chemiosmotic mechanism isresponsible for the active transport ofsucrose.

High H concentration

Low H concentration

Protonpump

Cotransporter

SucroseS

S

H

H H

24

© 2014 Pearson Education, Inc.

Loading of sugar

H2O

Vessel(xylem)

Source cell(leaf)

Sievetube

(phloem)

H2OSucrose

Uptake of water

Unloading of sugar

Recycling of water

Sink cell(storageroot)

H2OSucrose

Bu

lk f

low

by

neg

ativ

e p

ress

ure

Bu

lk f

low

by

po

siti

ve p

ress

ure

1

1

2

2

3

4 34

25