How do plants take How do plants take up water in a drying up - - PowerPoint PPT Presentation

How do plants take How do plants take up water in a drying up water in a drying climate climate

• Prof. Dr. Ulrich Zimmermann

ZIM Plant Technology GmbH Hennigsdorf near Berlin, Germany

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Water ascent in trees

The problem of water lifting in tall trees under drought is equivalent to the problem of water uptake against osmotic pressure

Mangrove, Australia Sequoia trees, California (up to 110m tall)

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Cohesion Theory

• Continuous water columns from the roots to the foliage
• Driving force: negative pressure gradients generated by transpiration
• Negative pressures of up to -15 MPa

3

Note that water under negative pressure is in a metastable state

Evidence for hydrophobic xylem walls

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Osmiophilic (lipid) lining of the inner xylem walls of a resurrection plant (a) and birch (b). Rise heights of water (blue) and benzene (grey)

T1 -weighted 1H NMR image of a well hydrated leaf in dependency of pressure

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Spin-density

Variation of balancing pressure with height measured on leafy twigs of a 32-m-tall Eucalyptus pilularis tree

04:30 05:30 06:30 07:30 60 70 80 90 100

T r.h. Relative humidity [%]

13:30 14:30 15:30 16:30

time [h] (EST) T r.h.

11:30 12:30 13:30 14:30

T r.h.

0.0 0.5 1.0 1.5 1 2 3 4 1.11 ± 0.22 1 2 3 4 0.58 ± 0.18

n

1 2 3 4 0.86 ± 0.28 15 20 25 30 10:00 11:00 12:00 13:00

Temperature [°C] r.h. T

0.0 0.5 1.0 1.5 1 2 3 0.35 ± 0.18

Pb [MPa]

2 4 6 0.31 ± 0.18 2 4 6 0.30 ± 0.10 0.0 0.5 1.0 1.5 1 2 3 4 0.40 ± 0.15 1 2 3 4 0.42 ± 0.20 1 2 3 4 0.62 ± 0.23

T

04:30 05:30 06:30 07:30 60 70 80 90 100

r.h. Relative humidity [%]

0.0 0.5 1.0 1.5 3 6 9 0.28 ± 0.15 2 4 6 8 0.19 ± 0.09 2 4 6 8 0.29 ± 0.18 11:30 12:30 13:30 14:30

T r.h.

February 28th

15 20 25 30 10:00 11:00 12:00 13:00

Temperature [°C] r.h. T

canopy level 28 m 16 m 6 m ground level

(b) (c) (d) (a)

March 1st February 27th

13:30 14:30 15:30 16:30

T r.h.

Australia, 2006

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Balancing pressures measurements on E. pilularis

Apical leafy twigs were taken from a 60m tall E.pilularis at 57m height and in parallel on the ground

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Australia, 2006

Plot of balancing pressures measured on twigs of P. nigra and Eucalyptus pilularis versus relative humidity

Balancing pressures depend on relative humidity, but not on height

100 80 60 40 0.0 0.5 1.0 1.5 2.0 2.5 100 80 60 40

1-5 m 5-15 m 15-25 m 25-35 m 57 m

Pb [MPa] Relative humidity [%]

n=10 n=11 n=10 n=15 n=48 n=58 n=22 n=86

100 80 60 40 20 0.0 0.5 1.0 1.5 2.0 2.5 1-5m 5-15m 15-25m

Pb [MPa] Relative humidity [%]

100 80 60 40 20

n=23 n=16 n=19 n=72 n=18 n=16 n=17 n=22 n=50

Eucalyptus pilularis Populus nigra

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Pattern of the amount of cohesive water and mobile water under rapidly changing weather conditions in E. pilularis

reference capillary

spin density image

cohesive water per cm3 wood

12.5 25.0 37.5 50.0 0.0 CWb,v [µl cm

• 3]

cohesive water per cm3 wood

12.5 25.0 37.5 50.0 0.0 CWb,v [µl cm

• 3]

mobile water per cm3 wood

212.5 325.0 437.5 550.0 100.0 MWb,v [µl cm-3]

mobile water per cm3 wood

212.5 325.0 437.5 550.0 100.0 MWb,v [µl cm-3]

NMR Jet discharge

branch pieces before compression branch pieces after decompression

x, embolised x, embolised x, liquid x, liquid x, liquid xylem sap embolised embolised gas x, liquid

branch pieces before compression branch pieces after decompression

x, embolised x, embolised x, liquid x, liquid x, liquid xylem sap embolised embolised gas x, liquid

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Pattern of the amount of CW, MW, and XW per cm3 of branches of a 32 m tall E. pilularis tree under very rapidly changing weather conditions

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Australia, 2006

Re-hydration of twigs by water uptake via leaves and/or bark as measured by NMR microscopy

Pb > 3.60 MPa

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Pb = 0.16 ± 0.01 MPa Pb = 0.20 ± 0.04 MPa

27 h

Pb = 1.13 ± 0.32 MPa Pb = 1.04 ± 0.19 MPa

18 h head-watered base-watered refilled under vacuum dried

Pb > 3.60 MPa

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Pb = 0.16 ± 0.01 MPa Pb = 0.20 ± 0.04 MPa

27 h

Pb = 1.13 ± 0.32 MPa Pb = 1.04 ± 0.19 MPa

18 h head-watered base-watered refilled under vacuum dried

phi b p x phe

Eucalyptus pilularis

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Cohesive water distribution pattern with height measured on birches

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Germany 2007

Salt-tolerance due to mucopolysaccharides

1H NMR-images of salt-tolerant Chaco trees

> 9 m 7 m 2 m 2 m 5 m 9 m

Bulnesia sarmientoi Astronium fraxinifolium

Zimmermann et al. (2002), Trees 16: 100-111. 13

Schematic diagrams of the cell turgor pressure probe and the xylem pressure probe

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Abbreviations: c = cell, Pc* =cell turgor (= Pc − Pam), Mc = microcapillary, Pt = pressure transducer, Mr = metal rod, Ms = micrometer screw, x = xylem vessel, Px = xylem pressure

Oscillation of xylem pressure measured in wheat roots

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Transpiration Xylem pressure Xylem pressure [MPa] Transpiration [mmol m-2 s-1]

15 30 45 60 75 90 105 120 0.30 0.35 0.40 0.45 0.50 0.55

Turgor pressure (MPa) Time (min)

Oscillation of turgor pressure measured on cortical cells of wheat

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Time of day Turgor pressure (bar) Xylem pressure (bar)

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Xylem and cell turgor probe measurements on liana

Salzburg, Austria

Xylem pressure in dependency on drought

cucumber tobacco 18

Relationship between the xylem pressure and the water potential of the cells

Assuming local equilibrium (water exchange time between xylem and tissue cells: a few seconds)

Px = Pc – πc

Development of pressure in the xylem cannot be considered separately from the tissue cells

(Renner 1915):

Pc = 0 cavitation

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Our understanding of nature Our understanding of nature will change with will change with progress of technology progress of technology

Max Planck Max Planck

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What is the Scholander pressure chamber measuring?

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Evidence arrived from the non-invasive,

• nline measuring leaf patch clamp pressure probe

The leaf patch clamp pressure probe

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The turgor pressure (Pc) in the leaf patch is

• pposed to the magnetic pressure (Pclamp). The

ZIM-probe measures the difference (Pp) between magnetic pressure and turgor.

Relationship between patch pressure and turgor pressure

clamp P a F a b c aP b p P ⋅ ⋅ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + = 1

Pp = patch pressure Pc = turgor pressure Pclamp = clamp pressure Fa = attenuation factor (compression of cuticle, cell walls and air-filled interspaces) a, b = elasticity constants

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Calibration of the leaf patch clamp pressure probe (Pp) against the leaf cell turgor pressure probe (Pc)

silicone oil cell sap volume displacement rod glass capillary

The turgor pressure probe

pressure transducer

cells

100 200 300 400 500 20 30 40 50 30 40 50 60 70 80 90

Pp [kPa] Pc [kPa] Pp [kPa]

probe 1 probe 2

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Diurnal Pp changes measured on grapevine leaves

a: sun-exposed leaf c: temperature and relative humidity b: shaded leaf

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Stomatal aperture oscillations are reflected in leaf patch pressure (Pp) oscillations

• live

banana

Pp = oscillation period about 20 min

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Typical multiple leaf patch clamp probe recordings

• n a 4-m tall avocado tree in Australia

red = east blue = north grey = south black = west

Arrows mark temporary sun-exposure

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Diurnal Pp curves, stem water deficit and soil water content measured on oak trees

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left: well-watered right: drought

Time delay of the maximum in LPCP-Probe readings and the minimum in dendrometer readings of the diurnal changes

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500 1000 SR [W/m²] 10 20 30 Ta [°C]

40 60 80 100

RH [%] 30 40 50 60 Pp [kPa] 03 05 08 10 13 16 18 21 00 02 420 435 450 465 Time [hh] Dendrometer [µm] 01/02 Jun 2009

• 03:00

00:00 03:00 06:00 09:00 12:00 15:00 10 20 30 40 50

Counts Time delay [hh:mm]

• 03:00

00:00 03:00 06:00 09:00 12:00 15:00 10 20 30 40 50

Counts Time delay [hh:mm]

control drought

Diurnal changes in patch pressure (Pp) and balancing pressure (Pb) values of well irrigated plants

Pb: north-directed leafs (n = 5 per data-point) Pp: east-directed leaf

Negev, Israel

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Plot of Pp (triangles) and Pb (circles) values versus the turgor pressure values, Pc, measured at the same time of the day by using the cell turgor pressure probe

31 100 200 300 400 500 600 35 40 45 50 55 60 0.5 1.0 1.5 2.0

Pp [kPa] ♦ Pc [kPa] Pb [MPa] Ο

The turgor pressure probe

cells

The data could be fitted by the transfer function (Fa = 0.3, Pclamp = 252 kPa, a = 6.8, b = 49.9 kPa; r2 = 0.93)

The role of mucilage in long-distance water transport and Foliar moisture uptake from the atmosphere

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( )

⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + − = −

= = , , , ,

ln

h x h x h x h x w w

a a RT P P V gh M

Presence of mucilaginous substances in fully functioning xylem vessels evidenced by alcian blue staining

Zimmermann et al. (2002), Trees 16: 100-111, Salix fragilis Astronium fraxinifolium Rhizophora mangle

light microscopy

5 µm

Rhizophora mangle

cryo-scanning electron microscopy

Astronium fraxinifolium

extracted xylem sap

Zimmermann et al. (2004), New Phytologist 162: 575-615 (Tansley Review).

Mucopolysaccharides lower the activity of water. MPS gradients can balance the weight of a water column at constant pressure.

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Kosteletzkya virginica

Applications: 1. Agricultural use of salt-affected tidelands 2. Biodiesel production (18 % seed oil content) 3. Good protein fodder for animals after oil extraction (26 %) 4. Landscape beautification for tideland (long flowering time)

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Mucilage –Alcian Blue precipitates in the xylem

Evidence for acid mucopolysaccharides located at the leaf surface and subsurface

Nothofagus dombeyi Populus nigra Eucalyptus pilularis Eucryphia cordifolia Astronium fraxinifolium Bulnesia sarmientoi

10 µm 10 µm 10 µm 10 µm 20 µm 20 µm 10 µm 10 µm 20 µm 20 µm 10 µm 10 µm

Moisture uptake by leaves from the atmosphere is apparently extremely facilitated by mucilage layers on the leaf surface and by epistomatal mucilage plugs.

35

Mucilage containing epistomatal plugs and LPCP probes measurements

grapevine with e.p. grapevine without e.p.

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Distribution of epistomatal mucilage plugs

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Resurrection plant Myrothamnus flabellifolia

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w e l l - h y d r a t e d d r y

lipid bodies (= )

Lipid bodies induce Marangoni (interfacial) streaming

The xylem is a full

• perating microsystem

Surface tension Interface induced water flow

light microscopy transmission electron microscopy

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Water ascent by Marangoni streaming

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mf = Maragoni flow cf = counter flow

Summary: The Multi-force Theory

• f water ascent in trees

Capillary forces Mucilage- mediated water lifting Marangoni streaming Xylem

• smotic

gradients Cellular osmotic pressure gradients Moisture uptake from the atmosphere

• 2
• 1

• 2
• 1

Pressure gradients Mycorrhiza- mediated water lifting

• 1]

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Acknowledgements

ZIM-Plant-Technolog

• Dipl. biol. Simon Rüger
• Dipl. biol. Wilhelm Ehrenberger
• Dipl. biol. Christina Sann
• Dipl. biol. Gertraud Zimmermann
• Dipl. ing. Ronald Fitzke
• Dipl. biol. Rebecca Bitter

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Thank you very Thank you very much for your much for your attention attention

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Simultaneous MRI measurements of flow velocity in the xylem and the phloem

44

Comparative measurements of leaf water status

grapefruit

• ak

Eucalyptus

Measurements at early spring; inset: measurements at autumn

leaf patch clamp pressure probe (Pp) pressure bomb (Pb) and cell turgor pressure probe (Pc) were used.

45

Time difference between Pp peaking and minimum trunk diameter: measurements on oak trees subjected to drought

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