Molecular characterization of pine response to insect egg deposition [Elektronische Ressource] / vorgelegt von Diana Köpke

Dkoepke

Sujets

• Biologie

Informations

• Publié par: freie_universitat_berlin
• Publié le: 01 janvier 2010
• Nombre de lectures: 18
• Langue: Deutsch

Extrait

Molecular Characterization of Pine Response
to Insect Egg Deposition




Dissertation zur Erlangung des akademischen Grades des
Doktors der Naturwissenschaften (Dr. rer. nat.)


eingereicht im Fachbereich Biologie, Chemie, Pharmazie
der Freien Universität Berlin



vorgelegt von
Diplom Biologin
Diana Köpke
aus Neubrandenburg




Jena, im Oktober 2010



































Diese Dissertation wurde am Max-Planck-Institut für Chemische Ökologie in Jena
1 2unter der Anleitung von Frau Prof. Dr. Monika Hilker , Herrn Dr. Axel Schmidt und
2 Herrn Prof. Jonathan Gershenzon angefertigt.

1 Institut für Biologie der Freien Universität Berlin in der Angewandten Zoologie/
Ökologie der Tiere

2 Max-Planck-Institut für Chemische Ökologie in Jena





1. Gutachterin: Prof. Dr. Monika Hilker
2. Gutachter: Prof. Dr. Jonathan Gershenzon
Disputation am 17.12.2010



Content


This thesis is based on the following manuscripts


I. Köpke D., Schröder R., Fischer H.M., Gershenzon J., Hilker M., Schmidt A.
(2008). Does egg deposition by herbivorous pine sawflies affect transcription
of sesquiterpene synthases in pine? Planta 228: 427-438, the original
publication is available at
http://springerlink.metapress.com/content/p77j66u3p1407474/



II. Köpke D., Beyaert I., Gershenzon J., Hilker M., Schmidt A. (2010). Species-
specific responses of pine sesquiterpene synthases to sawfly oviposition.
Phytochemistry 71: 909-917, DOI: 10.1016/j.phytochem.2010.03.017



III. Beyaert I. & Köpke D., Stiller J., Hammerbacher A., Schmidt A., Gershenzon
J., Hilker M. (submitted). Can insect egg deposition “warn” a plant of future
feeding damage by herbivorous larvae?



IV. Köpke D., Schmidt A., Gershenzon J., Hilker M. (manuscript). Ecological
roles of conifer sesquiterpenes.


Content

Table of content


Chapter 1 General introduction and thesis outline 1-9


Chapter 2 Does egg deposition by herbivorous pine sawflies affect
transcription of sesquiterpene synthases in pine? 11-33


Chapter 3 Species-specific responses of pine sesquiterpene
synthases to sawfly oviposition. 35-54


Chapter 4 Can insect egg deposition “warn” a plant of future
feeding damage by herbivorous larvae? 55-73


Chapter 5 Review: Ecological roles of conifer sesquiterpenes. 75-98


Chapter 6 Summary 99-102


Chapter 7 Zusammenfassung 103-107


Supplementary data 108-112


Danksagung – Acknowledgements
















General introduction and outline


Chapter 1

General introduction and outline


Plants produce a large variety of secondary metabolites that were once thought to be waste
products with no specific function in the life of the plant. Today we know that these products
fulfill a wide range of important purposes in an organism’s life. A simplified classification of
secondary metabolites distinguishes: nitrogen-containing compounds, acetylenic compounds,
phenolic compounds, and terpenoids (Schoonhoven 2005). Terpenoids are probably the
largest class among these secondary metabolites, and are synthesized by plants, fungi, and
metazoans for many biological purposes as have already early findings shown. They fulfill
purposes such as: anticompetitor adaptations, like allelopathy (Muller 1966) that e.g. reduces
germination rate in neighboring plants; mate attractants e.g. sex pheromones in insects and
higher animals (Riddifor & Williams 1967); trail markers e.g. in ants (Wilson 1965) insect
attractants (Edgar & Culvenor 1975) and of course repellants against enemies (Yoon et al.
2009). Terpenoids show an immense diversity of structures and their basic units and are
biosynthesized via two major pathways: the mevalonate (MVA) pathway in the cytosol or the
plastidic methylerythritol phosphate (MEP) pathway in the plastids.
Terpenoids are all derived from a five-carbon precursor, namely isopentyl
diphosphate (IPP) or its isomer dimethylallyl diphosphate (DMAPP). The condensation of
two, three, or four of these five-carbon units results in the formation of the intermediates
geranyl diphosphate (GPP), farnesyl diphosphate (FPP) and geranylgeranyl diphosphate
(GGPP), which are substrates of the terpene synthases. The terpene synthases produce the
basic carbon skeletons of the terpenoids, and their products can be classified according to the
number of their constituent isoprene units. Compounds with two isoprene units (10-carbon
atoms) are called monoterpenes, compounds with three isoprene units (15 carbon atoms)
sesquiterpenes, and compounds with four isoprene units (20 carbon atoms) diterpenes (Fig. 1).
Of these groups, monoterpenes and sesquiterpenes are often volatile (quickly vaporize in the
atmosphere) and thus function in plant communication with other organisms.
Other terpene classes with a higher molecular weight are triterpenes (30 carbon
atoms), tetraterpenes (40 carbon atoms), polyterpenes (> 40 carbon atoms) which will not be
further discussed in this review.


1
General introduction and outline

DiterpeneMonoterpene Sesquiterpene
limonene (E)- β-caryophyllene
abietic acid
OH
(E)- β-ocimene
(E)- β-farnesene
O
sandaracopimaric acid
1(10),5-germacradiene-4-ol
α-pinene
HO
HO O
longifolene

Fig. 1 Chemical structures of exemplarily monoterpenes, sesquiterpenes and diterpene resin acids.

In plants terpenes can act among others as defenses against herbivores. They can be
accumulated in the plant tissue as feeding deterrent as e.g. described for the milkweed plant
Asclepias curassavica that contains toxic cardenolides (steroidal glycosides that are derived
from triterpene) in the latex canals, which shows symptoms of poisoning when consumed by
the lepidopteran larvae Trichoplusia ni (Dussourd & Hoyle 2000). Another example is
Artemisinin which is a sesquiterpene lactone that is produced by the plant Artemisia annua.
Extracted or synthetic produced artemisinin was found to be effective against malaria and is
now commercially used as an antimalarial drug (Wright et al. 2010).
Terpenes being released in the atmosphere can also keep insects away, as was shown
for floral scents when testing the response of different insect species. Junker & Bluthgen
2
General introduction and outline

(2010) examined that floral scent can act not only as attractants but also as defensive cues to
deter unwanted floral visitors.
Especially conifers seem to have found sophisticated defense mechanisms by using terpenes.
Taking for example conifer resin, which is stored in resin ducts and specialized secretory
cells, and is a complex mixture of monoterpenes, sesquiterpenes and diterpenes (Persson et al.
1996; Sjodin et al. 1996; Fäldt 2000) that helps these long-lived trees withstand many
generations of pest attacks. Conifer resin can often be classified as a constitutive defense since
it is stored continuously in resin ducts in needles and stems and protects the tree against insect
infestation and fungal infection by acting as a toxin, an odorous repellent and a physical
barrier (Martin et al. 2002; Franceschi et al. 2005). A constitutive defense provides a plant
with constant protection, but requires investment of resources in defense without any
knowledge about whether attack is likely or not (Wagner et al. 2003)
Another defense strategy is the induction of defenses that are mobilized only after
initial herbivore or pathogen attack. In conifers, induced defense involves the formation of
additional resin ducts (known as traumatic resin ducts). Such a flexible response to herbivore
damage may allow plants to minimize their fitness cost of resistance to enemies by forming
defenses only as they are needed (Heil & Baldwin 2002; Cipollini et al. 2003). Contrary to the
constitutive defense, induced defenses require the plant to “notice” the attacker which may be
accomplished by recognition of certain specific elicitors that can be located in the saliva or
oviduct secretion of herbivore attackers (Hilker & Meiners 2010).
Inducible defense can be further classified into direct and indirect defenses (Dicke
1999) which is also true for the constitutive defense. The direct defense acts immediately
upon the attacker as toxins, repellents or digestibility reducers (Arimura et al. 2009). On the
other hand, indirect defenses involve the participation of