Plant volatiles: their importance in ecology and ... · Plant volatiles: their importance in ecology and ... plant volatilescan affect various community members that each ... of species

Plant volatiles: Plant volatiles: their importance in ecology and their importance in ecology and

atmosphere sciencesatmosphere sciences

Catherine Fernandez

Elena Ormeño Lafuente

DFCV Team

IMEP

OutlineOutline

Part I: biogenic volatile features1- What are plant volatiles ?2- Sources3- Types: examples of terpenoids and phenols4- Terpenoid precursors5- Plant volatiles as secondary metabolites

Part II: Functional levels of plant volatiles1- Plant 2- Ecosystem3- Atmosphere 4- Techniques used to study BVOC

OutlineOutline

Part I: biogenic volatile features1- What are plant volatiles ?2- Sources3- Types: examples of terpenoids and phenols4- Terpenoid precursors5- Plant volatiles as secondary metabolites

Part II: Functional levels of plant volatilesPart II: Functional levels of plant volatilesPart II: Functional levels of plant volatiles111--- Plant Plant Plant 222--- EcosystemEcosystemEcosystem333--- AtmosphereAtmosphereAtmosphere444--- Techniques used to study BVOC Techniques used to study BVOC Techniques used to study BVOC

11-- WhatWhat are plant volatiles ?are plant volatiles ?

Volatile organic compounds (VOC)

Biogenic (BVOC)

Anthropogenic (AVOC)

“Living plants”

Litter

Vegetation burning

Phytoplancton

Soil microorganisms

Small scale combustion

Mobile sources

Solvent use

Fossil fuel production and distribution

Chemical industry

Fossil fuel combustion

Molecules thermal energy

intermolecular attractions binding the molecules as liquid

Liquid → gas phase

11-- WhatWhat are are biogenicbiogenic VOC ?VOC ?

Low molecular weight Low boiling point

(e.g. isoprene: 34 oC)

Vapor pressure = atmospheric pressure

Low concentration of the volatiles in the atmosphere surrounding the plants

High vapor pressure (indicator of the volatility of a compound)

11-- WhatWhat are are biogenicbiogenic VOC ?VOC ?

Goldstein & Galbally 2007

Enviironmeme ntalSciiencece &

TechTech nology

5 10 15

22-- Source of Source of Biogenic VOC Biogenic VOC

Leaves, stems, flowers, fruits, trunk.

Transport of compoundsthrough the transpiration stream

Primary and secondary roots

Non-oxygenated=terpenes

Terpenoids

Oxygenated

Terpenoids

Most varied class of natural compounds (25,000)

Lipophilic properties

Mainly cyclic and unsaturated

The are classified according to the number of C atoms they have,which is multiple of 5

33-- Types of Biogenic VOC Types of Biogenic VOC

Alcohols, ketones, esters, aldehydes,

furanoids

Alkenes (terpenes)

Tiglic acid

Methylbutenol

Others: isoamyl alcohol, isovaleric acid, senecioicacid, ß-furoic acid,

Isoprene

(C5H8O2, acid)

(C5H8, alkene) (C5H10O, alcohol)

Hemiterpenoids → C5, only a few produced naturally


Terpenoids

Monoterpenoids → C10, thousands of different structures

α- pinene(alkene)

myrcene(alkene)

linalool(alcohols)

OH

Limonene(alkene)

camphor(ketone)

O

Linalool oxide(furanoid)

O

OH

Citronellal(aldehyde)

O

Methyl geranate(ester)

O

O

Terpenoids


Sesquiterpenoids → C15, most varied class of terpenoids

ß-caryophyllene(C15H24, alkene)

α-bergamotene

trans-nerolidol(C15H26O, alcohol)

dendrolasin(C15H22O, furanoid)

farnesene

Caryophyllene oxide (C15H24, alkene)

(C15H24, alkene)

HO

O

O

33--Types of Biogenic VOC Types of Biogenic VOC

Terpenoids

Terpenoids are isoprene units attached to one another by linking the head of one unit to the tail of another

head tail

the total number of double bonds, the position of the double bond in the final product the number of rings

Easy way to remember that terpenoidscontain a repetitive unit of 5 carbons that resembles isoprene

In reality, isoprene is not directly (or indirectly) involved in their synthesis, as it can not predict

Isoprene rule

Terpenoids ~ isoprenoids

33--Types of Biogenic VOC Types of Biogenic VOC

Biogenic (BVOC)1- 10 %

44--Terpenoid precursors Terpenoid precursors

Sesquiterpenoids

Hemiterpenoids

Monoterpenoids


Emplacement: cytosol and plastids of mesophyl cells

Cytosol

Plastids

Emissions through cuticle and stomata

PLASTIDSCYTOSOL

IDPIsopentenyldiphosphate

DMAPPDimethylallylpyrophosphate

Pyruvate

MEP pathway Methylerythritol pathway

ISOPRENE (C5)

Geranyl diphosphate (C10)

MONOTERPENES (C10)

Pyruvate

MVA pathway Mevalonate pathway

IDPIsopentenyldiphosphate

DMAPP


Actual precursors

Farnesyl diphosphate (C15)

SESQUITERPENES (C15)

+ IDPGeranyl diphosphate (C10)

Dimethylallylpyrophosphate

Secretory ducts

http://www.botany.hawaii.edu/faculty/Webb/BOT410/Secretion/secductpicea300.jpg

Emplacement: cytosol and plastids of secretorystructure cells

Thricome glands

Alfalfa

http://www.stonerforums.com/lounge/growfaq/1529_files/sp4r500w.jpg

http://www.nrc-cnrc.gc.ca/fra/education/biologie/galerie/trichome.html

Pinus sp.


Emissions through secretory structure cuticle

55-- Biogenic VOC as secondary metabolitesBiogenic VOC as secondary metabolites

Secondary metabolites Up to the 1960s: waste products of primary metabolism

Primary metabolites Essential for life

Anabolic and catabolic processus necessary for plant respiration, growth, reproduction and nutrition

Secondary metabolites

Anabolic and catabolic processusnecessary for plant respiration, growth, reproduction and nutrition

Up to the 1960s: waste products of primary metabolism

Primary metabolites Essential for life

Non ubiquitous within the plant

Non universal

Difficulties in establishing their function


Secondary metabolites Primary metabolites

Sugars, Amino acid Tricarboxilic acid Proteins Enzymes Nucleic acids Energy sources

Glycolisis Krebs cycle Photosynthesis and associated pathways

Carbon-based compounds

N-and S-based compounds

Terpenoids Benzenoids Fatty acid derivates

Carbon Hydrogen Oxygen

shikimate

pyruvate

Shikimate acid pathway

Mevalonate pathway (MVA)

Methylerythritol pathway (MEP)

Met

abol

ic P

roce

ssM

olec

ule

type


OutlineOutline

Part I: biogenic volatile featuresPart I: biogenic volatile featuresPart I: biogenic volatile featuresWhat are plant volatiles ?What are plant volatiles ?What are plant volatiles ?Sources of plant volatilesSources of plant volatilesSources of plant volatilesTypes: examples of Types: examples of Types: examples of terpenoidsterpenoidsterpenoids and phenolsand phenolsand phenolsPlant volatiles as secondary metabolitesPlant volatiles as secondary metabolitesPlant volatiles as secondary metabolites

Part II: Functional levels of plant volatilesPlant EcosystemAtmosphere Techniques used to study BVOC

Ecosystem

Part IIPart II-- Functional levels of Biogenic VOC Functional levels of Biogenic VOC

O

Atmosphere

+O3, NO3, OH

Key component in the biosphere-atmosphere interactions.

Affect other plants and organism

Favour the ecosystem perturbation

Plant Play an additional or alternative role in plant defences

Part IIPart II-- Functional levels of Biogenic VOC Functional levels of Biogenic VOC

Constitutive plant volatiles:

Induced plant volatiles

Produced only under stress conditions, de novo synthesized,

Phyto-alexines (plant pathology)

11-- Biogenic VOC as protective compoundsBiogenic VOC as protective compounds

HO

Produced permanently by the plant,

Phyto-anticipines

Protection of the plant against:

High light

High temperatures

Soil salinity

Water deficit

Air pollution

Cold stress

Vickers et al. (2009)Nature Chemical Biology

11-- Biogenic VOC as protective compounds Biogenic VOC as protective compounds

Biotic stress: Mechanical damage due to herbivores

Pathogens infection

Photo-, thermo- and oxido-protectors

Plant volatiles: indicators of the chance of a plant to survive in the ecosystem

High light

High temperatures

Soil salinity

Water deficit

Air pollution


Pathogens infection

Cold stress

trigger

generate

Biosynthetic pathways

Defensemetabolites

ROS production



0

50

100

150

200

250

300

350

400

25 30 35 40 45 50 55Temperature (oC)

Em

issi

ons

(nm

ol.m

-2.s

-1)

Monoterpene emissions of non-storing species increase with Temperature because:

Defense against high temperatures ?


Monoterpenes/isoprene in non-storing species

their volatilization from intercellular spaces is favored Monson et al., 1992, Kesselmeier and Staud., 2000, Guenther et al 1995,

0

50

100

150

200

250

300

350

400

25 30 35 40 45 50 550

50

100

150

200

250

300

350

400

Temperature (oC)

(pmol.m

in-1.m

g-1protein)

Enzym

atic activity

Em

issi

ons

(nm

ol.m

-2.s

-1)



Enzymatic activity

Monoterpene emissions of non-storing species increase with Temperature because:

their volatilization from intercellular spaces is favored


the enzymatic activity is favored

Monson et al., 1992, Kesselmeier and Staud., 2000, Guenther et al 1995,

0

50

100

150

200

250

300

350

400

25 30 35 40 45 50 550

50

100

150

200

250

300

350

400

Temperature (oC)

(pmol.m

in-1.m

g-1protein)

Enzym

atic activity

Em

issi

ons

(nm

ol.m

-2.s

-1)



Monoterpene emissions of storing species

Monoterpene emissions of storing species still continue under very high temperatures as they evaporate from the leaf reservoires


Monson et al., 1992, Kesselmeier and Staud., 2000, Guenther et al 1995,

-20

0

20

40

60

80

100

120

25 30 35 40 45 50

% P

hoto

synt

hesi

s

Temperature

((Delfine et al. 2002, New Phytol)

Cork Oak (Quercus suber)

Defense against temperature ?


Monoterpene-fumigated plants

Ambient air-fumigated plants

After fumigation with monoterpenes

Photosynthes is less inhibited by the temperature ramp than

in non-fumigated leaves

Monoterpenes: protection against

excess heat

Photo-, thermo- and oxido-protectors

Plant volatiles: indicators of the chance of a plant to survive in the ecosystem

High light

High temperatures

Soil salinity

Water deficit

Air pollution


Pathogens infection

Cold stress

trigger

generate

Biosynthetic pathways

Defensemetabolites

ROS production



Storage of toxic compounds in secretory structures

Defense against biotic damage

Secretory ducts

Alfalfa

Glandular thricome


Storage of toxic compounds in secretoy structures


Secretory ducts

Alfalfa

Glandular thricome


entrap organisms (Eisner et al 1998, PNAS)

decrease the radiation absorbance and heat load over leaf surface (Gonzalez et al., 2008)

Chemical defenses

Physical defenses:

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings


Plant that is locally damaged by a herbivore emits inducedvolatiles systemically, both above- and belowground. Theseplant volatilescan affect various community members that eachexert different selection pressures on the plant.

22-- Biogenic VOC in the ecosystemBiogenic VOC in the ecosystem

Exudation from roots

Reach other plants which will experience changes in their growth, distribution andreproduction

Produced by the plant and liberated to the host environment (atmosphere, soil) in important concentrations

Changes experienced can be negative (inhibition of germination: autotoxicity) or positive

Released from decomposing litter (leves, fruits, twigs)

Terpenoids as allelochemicals (allelopathy)Volatilisation from

leavesLeaching from leaves

by rain, fog or dew

BVOCs can act as neighbour detection signals

Competition impacts on BVOC emissions thus constituting a platform for plant–plant interactions.

Some are produced for easily appreciated reasons:

Most of the time the functional compound can not be identified because:

toxic and deterrents for organisms attractants of organisms

VOC-mixtures rather than single compounds are functional Variability of emissions with environmental conditions

Biogenic VOC : functions difficult to establishBiogenic VOC : functions difficult to establish

Plant volatiles

LightTemperatureNutrientsDrought

Biotic factors

AgeCompetitionAbiotic

factors

Environmental effect on BVOCs

Biogenic VOC : functions difficult to establishBiogenic VOC : functions difficult to establish

Plant flammabilityPlant flammability

FIREFUEL

IGNITION AND HEAT SOURCE

BVOC

(O2, O3, NO2 …)

OXYDIZERS


Low LFL (Lower Flammability Limit) At relatively low concentrations, the flammable substance can produce fire or explosion, when an ignition source is present

Low flash point At a relatively low temperature, the flammable liquid forms an ignitable mixture in air

-pinene : 38 °C

camphene : 36 °C

ß-pinene : 36 – 39 °C

ß-myrcene : 40 – 43 °C

ß-caryophyllene : 205 °C


Plant flammabilityPlant flammability


Litter flammability Litter flammability increases with terpene content

Ormeno el., 2009 Forest Ecology and Management

Pinus Pinus sp. sp. CistusCistus sp. sp.

Ston

e pine

Maritim

e pin

e

Alep

po

pine

Rock r

ose

Crimso

n spo

t

rockro

se

Laure

l Roc

krose

Leaf terpenecontent

Ignition delay, flame height, flame residence time, burned biomass, combustion time

Flammability

BVOC modeling:essential for understanding regional

and global atmospheric chemistry

consequently

BVOCBVOC

O3

participate

Aerosol

NOx

Health Climate change Photochemistry

44-- Biogenic VOC in the atmosphereBiogenic VOC in the atmosphere

Emission rates of species

Abiotic factors

Plant emissions: indicators of the potential implication of a plant to the be involved in air pollution

L, T, seasonality

Importance of Biogenic VOC at global scale Importance of Biogenic VOC at global scale

(millions tons.year-1)

CH4

350 350

(Keppler, et al. 2006, Nature)

120120CH4

25 25

CH4

(Kirschbaumet al. 2006 Funct Plant

Biol)

11501150

Guenther et al. 1995,

Zimmerman, 1992

BVOCs

44-- Biogenic VOC in the atmosphereBiogenic VOC in the atmosphere

Stern and Kaufmann.

1996

500500

isoprene

100100

AVOCs

Lerdau 2008 science

BVOC BVOC reactivityreactivity Teflon, glass Air chamber renewalwith « clean air »

DifferencesDifferences insideinside & & outsideoutside thethe cuvette cuvette T, L, inside and outside Plant physiology inside

MechanicalMechanical stress stress duringduringenclosureenclosurePlant adaptation to theenclosure for 1 day beforesampling

Branch enclosure chamber

44-- Techniques used to study BVOC emissionsTechniques used to study BVOC emissions

Sampling methodology Sampling methodology

GC/MS-FID – for BVOC sampling in situ Provides more specific measurements for a broad range of VOCs with hourly quantification

3

PTR-MS - for direct analysis of BVOC in situ

Measures highly volatile compounds and allows fast response quantification, but is does not completely speciate all BVOC

2

GC/MS –for analysis of BVOC collected in adsorbent cartridgesAllows analysis of sticky and reactive compounds that may not be detected with in situ systems due to sample handling1

44-- Techniques used to study BVOC emissionsTechniques used to study BVOC emissions

Sampling and analysis Sampling and analysis methodology methodology

Biogenic volatiles: multidisciplinary studies Biogenic volatiles: multidisciplinary studies

Fall lab and wound VOC:http://www.colorado.edu/chemistry/falllab/index.htmMETHANE:http://sciencenow.sciencemag.org/cgi/content/full/2009/11Fisher et al 1994Mettre une diapo en plus sur: methane emissions and Me

jasmonate or other hormones

TerpenoidsTerpenoids as photoas photo-- and and thermoprotectorsthermoprotectors ??

400 800 1200 1600 2000

0

1

2

3

4

0 10 20 30 40 50

1.5

0

1.0

0.5

0.0

What are plant volatiles ? What are plant volatiles ?

Low molecular weight & vapor pressure

Terpenoids Hemiterpenes Monoterpenoids Sesquiterpenoids Diterpenoids

Benzenoids Phenylpropanoids Phenols (= phenolics)

N- and S containing compounds (C + H + N/S)

Carbon-based compounds (C + H)

Fatty acid derivates

Source Source ofof volatiles in volatiles in thethe plantplant

Cell wall↓

Pectin deposition

Flowers↓

Floral scents

Cell membrane↓

Fatty acid peroxidation

Chloroplasts

Cytosol

Many tissues↓

Phytohormone

Oxygenated C5 – C6


Benzenoids100s VOC

Methanol

Ethanol

Secretorycavities

HemiterpenesMonoterpenes

Sesquiterpenes

MonoterpenesSesquiterpenes

Stems, leaves, roots

C1-C3 (formic acid, acetaldehyde)


Carbon-based compounds

Terpenoids

Phenols


N-based compounds (alkaloids)

S-based compounds

Carbon Hydrogen Oxygen

Their production and emission

can be constitutiveconstitutive (e.g., in response to abiotic drivers such as light or temperature) or

inducedinduced (e.g., in response to stress such as wounding)



herbivore

carnivore

Deterring


or attractant compounds

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

TerpenoidsTerpenoids over the seasonal cycle over the seasonal cycle

●

Natural water supply (control)

Water availability reduced (test )

Staudt et al 2002 J Geophys Res-Atmos

Kermes oak (Quercus ilex L.)

Can plants release CHCan plants release CH44 ??

Beech (Fagus sylvatica)(Keppler, et al. 2006, Nature)

Plants release CH4 emissions

Zea mays (Beerling et al. 2008)

Plant do not release CH4 emissions !!

CH4 emissions of land plants (living and dead) are 30% of the present

evaluated global sources

rather 6%(Kirschbaum et al. 2006

Funct Plant Biol)

Isop

rene

em

issi

on ra

te(n

mol

es.m

-2.s

-1)

Photon flux(µmol.m-2.s-1)

Temperature (ºC)

Emissions increase with Emissions increase with Temperature because their Temperature because their volatilization is favored volatilization is favored

Emissions increase with light Emissions increase with light because their synthesis is because their synthesis is dependent on photosynthesis dependent on photosynthesis

Isoprene Monoterpenesin storing species

Monoterpenesin storing species



Monoterpenesin storing species

Mon

oter

pene

emis

sion

rate

(nm

oles

.m-2

.s-1)

Indirect/delayed effect: Degradation via biotic & abiotic factors:

Atmosphere: wind, soil temperatures Soil: enzymes, clay minerals

Tritrophic relationships

Direct/rapid effect: Residence time Bioactive concentration Bitrophic relationships


TerpenoidsTerpenoids as as allelochemicalsallelochemicals ((allelopathyallelopathy))

Only litter of P. pinaster and P. halepensis burn when fire is set

P. pinaster litter

100 cm

PinusPinus burning (burning (Combustibility Table)

P. pinea litter

Litter of P. pinea is the only Pinus litter where fire is self-extinguishedafter some cm


Litter of P. pinea is the only Pinus litter where fire is self-extinguishedafter some cm

P. pinea litter


Vitreous fused silica disk

Temperature of 420°C

LitterLitter burning (burning (epirradiatorepirradiator technique) technique)

No wind and environmental temperature

Flame intensity

1

2

3

4

5

FIFI Flame height (cm)< 1

1-3

4-7

8-12

> 12


Ignition time

Time that litter takes to generate a flame


Combustion time

Time that litter (fuel) takes to burn, once the flame has appeared



Phenols (= phenolics)

Aromatic compounds

CH3Phenol Methyl phenol

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Plant volatiles: their importance in ecology and ... · Plant volatiles: their importance in ecology and ... plant volatilescan affect various community members that each ... of species