Herbivore induced emissions of methanol and ethylene: volatile signals in the defense response of Nicotiana attenuata [Elektronische Ressource] / von Caroline C. von Dahl

Vondahl

Informations

• Publié par: friedrich-schiller-universitat_jena
• Publié le: 01 janvier 2007
• Nombre de lectures: 3
• Langue: English
• Poids de l'ouvrage: 4 Mo

Extrait

Herbivore-induced emissions of methanol and ethylene:
volatile signals in the defense response of
Nicotiana attenuata




Dissertation


zur Erlangung des akademischen Grades
doctor rerum naturalium (Dr. rer. nat.)












vorgelegt dem Rat der Biologisch-Pharmazeutischen Fakultät
der Friedrich-Schiller-Universität Jena



von Diplom-Biologin
Caroline C. von Dahl
geboren am 3.12.1975 in Frankfurt a.M.






























Referees:
1. Prof. Dr. Ian T. Baldwin
2. Prof. Dr. Ralf Oelmüller
3. Prof. Dr. Corné M.J. Pieterse

thDate of Oral Examination: June 25 2007
ndDate of Public Defense: July 2 2007 Table of Contents______________________________________________________________________________________________________
Table of Contents
1. Introduction 1
1.1. Plants: not quite as passive as they look 1
1.2. Mindless mastery of stress responses 2
1.3. Plant species to study plant signaling 6
1.4. Volatile signals in the defense response of N. attenuata 8
2. Manuscripts 9
I. Contents and Author’s Contribution 9
Manuscript 11-23
C.C. von Dahl, M. Hävecker, R. Schlögl, and I.T. Baldwin (2006)
Caterpillar-elicited methanol emissions: a new signal in plant-herbivore
interactions?
The Plant Journal, 46: 948-960

II. Contents and Author’s Contribution 25
Manuscript 27-35
C.C. von Dahl and I.T. Baldwin (2007)
Deciphering the role of ethylene in plant-herbivore interactions
Journal of Plant Growth Regulation, early online

III. Contents and Author’s Contribution 37
Manuscript 39-53
C.C. von Dahl, R.A. Winz, R. Halitschke, F. Kühnemann, K. Gase, and
I.T. Baldwin (2007)
Tuning the herbivore-induced ethylene burst: the role of transcript
accumulation and ethylene perception in Nicotiana attenuata
The Plant Journal, 51: 293-307

IV. Contents and Author’s Contribution 55
Manuscript 57-66
O. Barazani, C.C. von Dahl, and I.T. Baldwin (2007)
Sebacina vermifera promotes growth and fitness of Nicotiana attenuata
by inhibiting ethylene signaling
Plant Physiology, 144: 1223-1232

V. Contents and Author’s Contribution 67
Manuscript 69-72
I.T. Baldwin, R. Halitschke, A. Paschold, C.C. von Dahl, and C. Preston (2006)
Volatile signaling in plant-plant interactions: “talking trees” in the genomic era
Science, 311: 812-815

Table of Contents______________________________________________________________________________________________________
3. Discussion 73
3.1. Deciphering the role of MeOH 73
3.2. Ethylene: Jack of all trades, master of none? 75
3.2.1. Concentration-dependent regulation of plant growth and development 76
3.2.2. Localized regulation of ethylene biosynthesis 77
3.2.3. Signal crosstalk: the key to specificity 78
3.2.4. Priming responses by altered sensitivity 79
3.3. Conclusion 80
4. Summary 82
5. Zusammenfassung (German) 83
6. References 86
7. Acknowledgements 91
8. Declaration of Independent Assignment 92
9. Curriculum vitae 93
10. Supplementary Material 95
10.1. Manuscript I 95
10.2. III 101
10.3. Manuscript IV 111

1.1. Plants: not quite as passive as they look 1. Introduction______________________________________________________________________________________________________
1. Introduction
This introduction provides a general background on plant signaling. Firstly, the adaptive
responses of plants, which constitute their phenotypic plasticity, are introduced (1.1. Plants: not
quite as passive as they look) and four examples of stress perception through environmental
cues are described (1.2. Mindless mastery of stress responses). Secondly, an overview of three
different plant species that are extensively studied in the context of hormone signaling is given
(1.3. Plant species to study plant signaling) and volatile organic compounds (VOCs) as signaling
molecules in plants are described (1.4. Volatile signals in the defense response of Nicotiana
attenuata).
Detailed introductions of the two volatile compounds methanol (MeOH) and ethylene in
the context of Nicotiana attenuata’s interaction with Manduca sexta, its specialized natural
herbivore (Manuscript I to III), with Sebacina vermifera, a growth-promoting endophytic fungus
(Manuscript IV), and with other plants (Manuscript V) are presented at the beginning of the
respective manuscript.
1.1. Plants: not quite as passive as they look
Despite their sessile life plants actively regulate growth, development, and physiological
processes that allow them to survive a constantly changing environment. Their spatially fixed
living requires the ability of terrestrial plants to use solar energy, converted by the photosynthetic
machinery, to feed themselves (autotrophy). In contrast to the energy-providing process of
photosynthesis, the adjustment of the plant’s phenotype to the prevailing environment is an
energy-demanding task. Environmental heterogeneity is one of the most important selective
forces in nature (Hutchings and Kroon, 1994). Physiological and developmental plasticity, known
as phenotypic plasticity, involves the perception, processing, and integration of environmental
information by an organism (Novoplansky, 2002). In the regulation of the underlying processes
that lead to an adapted phenotype lies an intriguing difference between animals and plants.
Plants lack a central nervous system (CNS), which allows for precise signal transduction and
rapid responses in animals, and must rely instead on a slow, hormone-based set of feedback
loops (Givnish, 2002).
What environmental changes do plants respond to, and how do they recognize such
changes? The abiotic and biotic surroundings of a plant provide detectable information (cues)
which are then translated into specific responses. In the abiotic environment, salinity, drought,
radiation, touch, and bending are factors that are identified by such cues as ionic strength,
disruption of membrane integrity, conformational change of specific molecules, and turgor
(Ballaré, 1999; Braam, 2005; Bray, 1997). Changes in these plant parameters will elicit a specific
response that is propagated within the plant by signal networks. Biotic stress is caused by all
kinds of organisms: bacteria, fungi, nematodes, arthropods, reptiles, and mammals, as well as
11. Introduction 1.2. Mindless mastery of stress responses______________________________________________________________________________________________________
plants of the same and other species. Typical cues of the living environment are chemical
compounds that are specific for the attacker or competitor, such as cell wall fragments of fungi
and specific bacterial enzymes (Boller, 1995), inceptins, glucose oxidase (GOX), and fatty acid-
amino acid conjugates (FACs) in the oral secretions (OS) of attacking lepidopteran larvae (Alborn
et al., 1997; Musser et al., 2002; Schmelz et al., 2006), or volatile compounds emitted by
neighboring plants (Farmer, 2001; Gershenzon, 2007). Additionally, non-chemical cues, such as
time resolved wounding and changed light ratios, inevitable consequences of chewing insects
and neighboring plants, elicit specific responses in the plant (Ballaré, 1999; Mithöfer et al., 2005).
Plants are constantly exposed to several cues, most of which are commonplace, and the
responses they elicit are daily routine. The questions arise: when do plants experience stress
and when and how do they decide to respond? If the detected parameters indicate an
unfavorable state for the plant, e.g. a prolonged encounter of this state would lead to a fitness
decline the plant’s responses can be called stress responses. A fitness cost can be defined as
reduced performance of a plant such as lowered seed set or decreased viability of seedlings in
the next generation. The permanent protection against an unfavorable state which is not
prevailing would imply fitness costs to the plant if the defense or protection is resource
demanding. Examples of costly stress responses are pigments that prevent damage by exposure
to UV radiation and defense compounds that deter pathogens and herbivores (Baldwin, 1998;
Zavala and Botto, 2002). Phenotypic plasticity, the continuous adaptation to mitigate stress, is a
means to increase plant fitness in a changing environment by saving costs of permanent
protection when not needed. “Thus, although upon casual observation plants look as though they
are not doing very much, within, innumerable pathways are working overtime to keep things as
they are, while maintaining a constant state of readiness: n