La paléochimiotaxonomie
expérimentale :
Un nouvel outil pour le traçage des
changements paléofloristiques et
paléoclimatiques.
Présentation et application aux
conifères fossiles.Y. Hautevelle, R. Michels, B. Farre, F. Lannuzel, F. Malartre
Botanical chemotaxonomyIntro-duction
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Terpenoids have a chemotaxonomic value and are
thus specific of some taxa
Molecular composition :- lignin- carbohydrates- lipids, e.g. terpenoids
conifers
Abietic acid
angio-sperms
lupeol
From bioterpenoids to geoterpenoidsIntro-duction
BIOSPHERE
GEOSPHERE
Sedimentary basin
transport
sediment
bioterpenoids
Geoterpenoids can keeptheir initial
chemotaxonomic value
conifers
angio-sperms
Geoterpenoids ormolecular biomarkers
Diagenetic
transformations
angio-sperms
conifers
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Distribution of plantbiomarkers
Palaeofloristic compositionon emerged lands
Intro-duction Palaeofloristic and palaeoclimatic reconstructions
The distribution of plant biomarkers reflect the palaeofloristic composition during the deposition
cypres
fern
Interpretation in terms of palaeofloristic composition
pine pineangio-
sperms
sequoia
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Intro-duction
desertic climate
temperate climate
tropical climate
polar climate flora ↔ climate
Relations between floras and climates
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Chemostratigraphy of vascular plant biomarkersIntro-duction
stratigraphicrecord
palaeobiodiversity
palaeoflora
palaeoclimate
T°, humidity
desertic climate
Geolo
gic
al ti
mes
tropical climate
temperate climate
Molecular facies
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Advantages of palaeochemotaxonomy
but fossils are scarse
Improved approaches for palaeofloristic
and palaeoclimatic reconstruction
PALAEOBOTANIC(fossil plants)
PALYNOLOGY(spore & pollen)
but spores & pollen are not easily related to plant taxa
BOTANICAL PALEOCHEMOTAXONOMY (plant biomarkers)
-widespread in the sedimentary record
- related to plant taxa when they have a palaeochemotaxonical value
however plant biomarkers are :
BUT, presently molecular databases contain many gaps
Intro-duction
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Aims of experimental palaeochemotaxonomy
plantbiomarkers
palaeofloristic and palaeoclimatic proxies
➜ new technic of artificial maturation of fresh plants (confined pyrolysis).
➜ experimental "simulation" of the plant diagenesis & fossilisation (at the molecular scale).
➜ Aim :
Molecularsystematic
Botanicalsystematic
Intro-duction
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
I.01 Experimental and analytical procedures
Fresh plant Sealed gold tubes Confinedpyrolysis
Solubilisation ofterpenoids (CH2Cl2)
Molecular analysis(GC-MS)
Aliphatic
Aromatic
Polar
FractionationConclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Composition of fresh Abies pinsapoII.01
Fresh Abies pinsapoMethylated total fraction
Retention time
Diagenetic evolution of abietanoic acids
Fresh Abies pinsapo contain large amounts
of abietanoic acids
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
II.02
150°C
200°C
250°C
280°C
300°C
Other pyrolysis parameters :duration : 24 h ;pressure : 700 bars.
Diagenetic evolution of abietic acid
280°C Presence ofaromatic diterpanes
Pyrolysed Abies pinsapoTotal fractionm/z 219, 223, 237, 239, 241
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Calibration of the pyrolysis temperature
II.03
phytene
280°C
280°C presence of diterpanesclassically detected
in the geosphereLiAlH4
Unsaturated abietanes
not satisfying
Pyrolysis with LiAlH4
Pyrolysed Abies pinsapoAliphatic fraction TIC
280°CSaturatedabietanes
labdanes
Diterpane diagenesis
Pyrolysed Abies pinsapoAliphatic fraction TIC
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Generation of saturated diterpanes
II.04Pyrolysed Abies pinsapoAliphatic fraction TIC
Pyrolysed Abies pinsapoAromatic fraction TIC
pyrolysed Abies pinsapoPolar fraction TIC
with LiAlH4
280°C
WithoutLiAlH4
280°C
withoutLiAlH4
280°C
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Palaeochemotaxonomy of a virtual fossil Abies pinsapo
Typical molecular signature of fossil
Pinaceae
II.05
Aliphatic fractionTime : 24 h, pressure : 700 bar, temperature : 280°C, WITH LiAlH4
Aromatic fractionTime : 24 h, pressure : 700 bar, temperature : 280°C, WITHOUT LiAlH4
Polar fractionTime : 24 h, pressure : 700 bar, temperature : 280°C, WITHOUT LiAlH4
Determination/prediction of the fossil molecular signature
of the pyrolysed plant
The reproduction of this procedure on a great number of plant taxa will considerably increase our knowledge in palaeochemotaxonomy and contribute
to the reconstruction of ancient floraConclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Summary of the experimental procedure
Conifers currently studied
Coniferal order is composed of 7 familiesAraucariaceae
3 Agathis, 8 Araucaria & 1 Wollemia
Cupressaceae1 Calocedrus, 4 Chamaecyparis, 2 Cupressus, 5 Juniperus,
1 Microbiota, 3 Thuja & 1 Thujopsis
Pinaceae 4 Abies, 3 Cedrus, 4 Larix, 5 Picea, 4 Pinus, 1 Pseudotsuga &
1 Tsuga
Podocarpaceae4 Podocarpus
Sciadopityaceae1 Sciadopitys
Taxaceae2 Taxus, 2 Cephalotaxus, 1 Torreya
Taxodiaceae 1 Cryptomeria, 2 Cunninghamia, 1 Sequoiadendron, 1 Meta-
sequoia, 1 Sequoia & 2 Taxodium
69 species studied forexperimental palaeochemotaxonomy
III.01
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Example of Araucariaceae (sesquiterpenoids)
Araucariaangustifolia
Araucariaaraucana
Araucarialaubenfelsii
n-C14 n-C15
Aliphatic fraction Aromatic fraction
farnesane
bisabolanes cadalanescadalenepentaMedi
hydroindenes
chamazulene ?
curcumenes
III.02
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
III.03
Araucariaangustifolia
Araucariaaraucana
Araucarialaubenfelsii
labdanes
(iso)pimaranes
MonoaromaticLabdane ?
Monoaromatictetracyclic diterpane
Aromaticabietanes
Aliphatic fraction Aromatic fraction
Example of Araucariaceae (diterpenoids)
béyérane
phyllocladaneskauranes
phyllocladanes
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemo-taxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
Results for the whole Coniferale orderIV.01
AraucariaceaeHigh abundance of tetracyclic diterpanes
Low abundance of tricyclic diterpanes
CupressaceaeHigh diversity between the different genera
Cuparene, cedrane and totaranes seem specific
Systematic occurrence of ferruginol and occasional occurrence of tetracylic diterpanes
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemotaxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
IV.02
PinaceaeSystematic presence of dehydroabietic acid and dehydroabietol
Some fonctionnalised compouds seem to be specific for some genera
TaxodiaceaeHigh diversity between the different genera
Presence of ferruginol & sugiol
Occasional occurrence of tetracyclic diterpanes
Results for the whole Coniferale order
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemotaxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae
ConclusionsConclusion
Experimental Palaeochemotaxonomy ➜ pertinent and innovative approach
investigate the molecular composition of fossil plants from their present
representatives
BOTANICAL PALAEOCHEMOTAXONOMY(plant biomarkers)
PALEOBOTANIC(fossil plants)
PALYNOLOGY(spore & pollen)
Molecularsystematic
Botanicalsystematic
Conclusions
II. Methodologydevelopment
Introduction
IV. Palaeochemotaxonomyof conifers
I. Experimentaland analyticalmethodology
III. Example ofAraucariaceae