41 documents found

Dissertation
All rights reserved
2016

Probing the herbivores responses to plant defenses using plant-mediated...

Nicotiana attenuata (Solanaceae) produces 17-hydroxygeranyllinalool diterpene glycosides (HGL-DTGs) in starch-equivalent concentrations that thwart the growth of its specialist lepidopteran herbivore Manduca sexta (Lepidoptera, Sphingidae). Lyciumoside IV and its malonylated forms, nicotianoside I and...
Dissertation
2015-08-21

The role of cytokinins in plant-herbivore interactions : response to herbivory ...

Cytokinins (CK) are a group of phytohormones that are well-known to regulate the plant development, but also environmental interactions. The most prominent examples for CK functions in plant-insect interactions are the leaf miner and sawfly induced formation of “green islands” and leaf galls, respectively....
Dissertation
2015-01-28

Integrating below- and above-ground signaling in Nicotiana attenuata

In this thesis, I investigate the role of the roots in processes which have so far mostly described within leaves. I manipulate gene function in the roots, and ask whether root gene function affects plant responses to above-ground herbivore attack and above-ground herbivore preference. I establish an...
Dissertation
2014-11-25

Manipulation of the plant microbiome : antimicrobial peptide expression in nic ...

Endophytic bacteria are believed to be important for plant growth, plant health and plant resistance. But the exploration of these roles in nature is difficult. To be able to manipulate endophytic bacteria of Nicotiana attenuata, I made 11 different genotypes for the constitutive expression of antimicrobial...
Dissertation
2014-10-17

Coping with ephemeral resources and unpredictable hosts : nitrogen allocation ...

This thesis explores phenotypic plasticity in the interaction of the post-fire annual tobacco Nicotiana attenuata with two herbivores: the lepidopteran folivore Manduca sexta and the hemipteran seed predator Corimelaena extensa. Due to mass-germination after fires, N. attenuata grows under strong intra-specific...
Dissertation
2014-07-28

Making love and war : jasmonate signaling in herbivore defense and flower deve ...

The goal of my work presented in this thesis was to investigate the regulatory role of JAs-homeostasis during the herbivore induced defense activation and floral development in the wild tobacco Nicotiana attenuata. Biosynthetic pathways are most commonly investigated by silencing or overexpression of...
Dissertation
2014-05-09

Timing for outcrossing : circadian clock regulates floral rhythms with large f ...

Like most organisms, plants need to keep a daily rhythm to synchronize their inner functions to the available energy and nutrients; even due to its sessile nature it’s especially important for a large group to find ways to reproduce by outcrossing. The endogenous clock regulates metabolic processes related...
Dissertation
2014-04-29

Revealing manduca sextas nicotine metabolism and its ecological consequences...

Insects have developed a myriad of adaptations to live and evolve. Manduca sexta, a specialist lepidopteran herbivore of Nicotiana attenuata, has developed a remarkable adaptation to tolerate a toxic alkaloid ‘nicotine’ that it ingests from its host plant Nicotiana attenuata. The mechanism of nicotine...
Dissertation
2014-04-07

Integrative statistical methods for decoding molecular responses to insect...

This work focuses on the development of statistical methods to select features (genes and metabolites) exhibiting induced local and systemic defense responses to insect attack in Nicotiana attenuata along with the extraction of additional information regarding their timing of action. To characterize...
Dissertation
2014-02-12

Mutualistic plant-microbe interactions in Nicotiana attenuata : from bacterial ...

Endosphere-inhabiting mutualistic bacteria establish intimate relationships with their host plant and often provide services like plant growth-promotion (PGP) or disease protection. How plants select for these microbes and which mechanism of PGP are employed remain mostly elusive. I assessed the relevance...
Dissertation
2014-01-31

The control of plant defense responses and seedling growth during interactions...

The wild tobacco species Nicotiana attenuata needs to tailor its defense responses against herbivores and pathogens most efficiently, requiring sophisticated signaling systems to distinguish its individual attackers. One of these signaling components is the phytohormone jasmonic acid (JA) which is produced...
Dissertation
All rights reserved
2013-08-29

Molecular response of nicotiana attenuata to herbivory and solar UVB

Plants have coexisted with insects for approximately 400 million years. During this time, the interactions between flora and fauna have driven coevolutionary and reciprocal changes, resulting in a complex mosaic of plant defenses and insect counter-defenses. In addition, abiotic stress such as UVB radiation...
Dissertation
2013-08-20

Trade-offs of induced herbivore defense in Nicotiana attenuata : the role of e ...

In dieser Arbeit wurden die Kosten der frühen Verteidigungssignalkette, die oberhalb der Jasmonsäure (JA) entstehen, für die pflanzliche Fitness, untersucht. Darüber hinaus wurden die Nachteile der Biosynthese Stickstoff (N)-haltiger Verteidigungsmetabolite für das Wachstum durch die Nutzung einer gemeinsamen...
Dissertation
2013-06-11

Identification of novel regulatory mechanisms involved in plant-herbivore...

The jasmonate signaling is one of the most studied hormone signaling pathways in plants that mediate important physiological processes. When plants are attacked by herbivores, they induce the biosynthesis of huge pools of jasmonic acid (JA) and the biologically active (+)-7-iso-jasmonoyl-L-isoleucine...
Dissertation
2013-05-30

Multiple functions of Jasmonate ZIM domain (JAZ) proteins in N. attenuata...

The Jasmonate-ZIM domain (JAZ) proteins are key repressor of jasmonic acid (JA) signaling in plant. I identified 12 novel JAZ proteins in the native tobacco Nicotiana attenuata The NaJAZ genes showed spatially and temporally different expression patterns after simulated herbivory. N. attenuata plants...
Dissertation
2013-01-31

The role of small RNAs in plant and insect interactions

Nicotiana attenuata is a native plant which regularly attacked by number of insect herbivore species. N. attenuata recognizes herbivores by the content of herbivore oral secretions (OS). Elicitors in OS can rapid induce jasmonate response and large-scale transcriptional and metabolic changes. This is...
Dissertation
2012-12-10

Nicotiana attenuata protein kinases mediate plant growth and resistance...

Protein kinases modulate developmental and adaptation processes in the plant kingdom. While MAPK signaling has been intensively studied for the involvement in growth, defense and growth regulation, more and more studies have shown that CDPKs also function in these physiological processes. N. attenuata...
Dissertation
2012-11-12

The ecological role of the activation of oxylipin biosynthesis in plants...

In this work, I describe the activation and regulation of oxylipin signaling pathways in Nicotiana attenuata in response to herbivory. When the tobacco hornworm, Manduca sexta, feeds on N. attenuata, the plant perceives fatty acid-amino acid conjugates like 18:3-Glu present in the insect’s oral secretions....
Dissertation
2012-11-05

Trichomes in plant-herbivore interactions : the first line of defense of the w ...

Trichomes represent a first meal for neonate larvae of the tobacco hornworm Manduca sexta and we explored the functions of their exudates and contents in terms of plant defense. We analyzed the composition of O-acyl sugars in Nicotiana attenuata and demonstrated that their mixture is even more complex...
Dissertation
2012-07-23

Early herbivory-induced responses in plants

In this thesis I analysed herbivore perception and herbivory-induced signalling in two plants species, the solanaceous plant N. attenuata and the brassicacean plant A. thaliana. Herbivore detection can be divided into perception of molecular events inflicted by tissue damage, classified as damage-associated...