Evolution of disease resistance genes in wild tomato species [Elektronische Ressource] / vorgelegt von Anja Christina Hörger

Anja Hoerger

Sujets

• Biologie

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2011
• Nombre de lectures: 66
• Langue: Deutsch
• Poids de l'ouvrage: 6 Mo

Extrait

Dissertation zur Erlangung des Doktorgrades der Naturwissenschaften an der Fakultät für
Biologie der Ludwig-Maximilians-Universität München

EVOLUTION OF DISEASE RESISTANCE GENES
IN WILD TOMATO SPECIES





Anja Christina Hörger





München 2011


EVOLUTION OF DISEASE RESISTANCE GENES
IN WILD TOMATO SPECIES







Dissertation
der Fakultät für Biologie
der Ludwig-Maximilians-Universität München





vorgelegt von
Anja Christina Hörger
aus München







München, den 05.04.2011





























1. Gutachter: Prof. Dr. Wolfgang Stephan
2. Gutachter: Prof. Dr. John Parsch
Datum der mündlichen Prüfung: 30. Mai 2011
i Erklärung:

Diese Dissertation wurde im Sinne von §12 der Promotionsordnung von Prof. Dr. Wolfgang
Stephan betreut. Ich erkläre hiermit, dass die Dissertation nicht einer anderen
Prüfungskommission vorgelegt worden ist und dass ich mich nicht anderweitig einer
Doktorprüfung ohne Erfolg unterzogen habe.


Ehrenwörtliche Versicherung:

Ich versichere ferner hiermit ehrenwörtlich, dass die vorgelegte Dissertation von mir
selbständig und ohne unerlaubte Hilfe angefertigt wurde.

München, den 05.04.2011




Anja Hörger
iiNOTE

In this thesis, I present my doctoral research, all of which has been done by myself except for
the following: The population-based study on five resistance genes was done in collaboration
with Lukasz Grzeskowiak, who sequenced Pto and Fen, and with Martin Groth, who
sequenced Prf. The species wide sampling approach was done in collaboration with Katharina
Böndel, who kindly provided Pto and partly Rin4 sequence data. Hilde Lainer and Gisela
Brinkmann provided excellent technical assisstance (sequencing of the reference loci and
partly Pfi). Aurélien Tellier contributed to the gene conversion analysis for the Rcr3 gene.

The results of my thesis have contributed to the following publication:

* *Rose, L. E., L. Grzeskowiak , A. C. Hörger , M. Groth, and W. Stephan (2011). Targets of
selection in a disease resistance network in wild tomatoes, Molecular Plant Pathology
*(accepted pending minor revisions), These authors contributed equally.


iiiACKNOWLEDGEMENTS

First, I would like to thank Prof. Wolfgang Stephan for convincing me to join the Population
Genetic group at the end of my Diplom studies and for offering me the opportunity to do my
PhD in his group. He supported and motivated me whenever it was needed and he always had
a sympathetic ear for me. I enjoyed my time in the group very much and learned a lot. I also
thank Laura Rose for the opportunity of doing my PhD in her lab, for providing everything I
needed to complete my work and for motivating discussions. Both, Wolfgang and Laura,
contributed largely to the improvement of my scientific skills.

Further, I am very grateful to Aurélien Tellier for continued encouragement, mental and
scientific support, plenty of fruitful discussions, awsome ideas and so much more.

I would not have been able to perform an interesting part of my project – the Rcr3 functional
studies – if it had not been for Renier van der Hoorn. He welcomed me in the Plant Chemetics
Lab in the Max Planck Institute in Cologne and provided everything necessary to complete
the functional experiments. His encouragement contributed largely to the successful
completion of this project. Further, I would like to thank Muhammad Ilyas for giving me a
great start in the world of plant chemetics and for tolerating my attempts to stress out the
whole group.

A huge „Thank you“ goes to the whole Munich Evolutionary Biology Group. I had a great,
memorable, funny, inspiring time with you in, but also outside the lab. Hilde Lainer for
excellent technical support and for making the lab a warm place, Gisela Brinkmann for
excellent technical support and getting the nearly impossible working, Simone Lange for the
crazy time in the lab (involving Gummibärchen, Dornenvögel, dry ice…), Iris Fischer for a
memorable journey to Egypt, Claus Kemkemer for his constant and nevertheless appreciated
visits in the lab, Winfried Hense for political and magical discussions, Miri Linnenbrink for
her taste of music and her sunny personality, Katharina Böndel for being a model Diplom
student, Lukasz Grzeskowiak for fruitful collaboration, Francesco Paparazzo for entertaining
episodes in the lab, Mamadou Mboup for inspiring discussions, a great time in the office and
his occasional confusion, Anne Wilken and Hedwig Gebhart for their helpfulness, Anica
Vrljic for being the heart and spirit of the group, Ingrid Kroiss for her irreplaceable support
whenever one has to deal with German administration, John Parsch and Dirk Metzler for
iv helpful comments during my seminar talks, Lena Müller for her pleasant company, Martin
Hutzenthaler for the great skiing trips, Rayna Stambolyiska for her patience and a great time
in the office, Astrid Stück for a great time in the office as well, Sonja Grath for the relaxing
barbecue sessions, Carlos Merino for never getting bored because of him, Nicolas Svetec for
the nice hiking and skiing trips, Kim Steige for her pleasant personality, Robert Piskol, Ana
Catalán, Susi Voigt, Annegret Werzner and Ricardo Wilches for entertaining discussions and
Lisha Naduvilezhath, Stefan Laurent, Daniel Zivkovic, Meike Wittmann, Pavlos Pavlidis,
Stephan Hutter, Pablo Duchén for sporty hours in our football team. And not to forget: W.
Schnitzel, who provided a good piece of entertainment.

I would like to thank everybody in the Plant Chemetics Lab in Cologne for the great working
atmosphere: Selva Kumari for help with the protein purification and great bench
neighbourship, Izabella Kolodziejek (the Polish Princess) for entertaining and encouraging
discussions, Takayuki Shindo for useful hints and the course in Japanese, Farnusch Kaschani,
Kerstin Richau and Christian Gu for useful comments and good mood in the lab, Johana
Misas for encouraging lunch time discussions, Bikram Pandey for help with the Typhoon
scanner and not feeling bored when waiting for the results. I am also very grateful to Madlen
Vetter for generously offering me a home.

Thank you to Hans Nitschko, who encouraged me to “run head first through the wall – if it is
not too solid”. I did so and it was the right decision.

A big thanks goes to my dear friends for legendary times and conserving my mental health:
Thomas Kunze, Martina Eder, Corinna Steinmeyer, Andy Stöger, Wolfgang Hell, Susanne
Spieß, Andrea Brandmeier, Steffi Tews, Achim Gütlein and Xaver Steemann.

Last but not least, I owe very special thanks to my family, especially my parents and my
sister, who are always there for me and support me in every respect. Without you, this would
not have been possible.





v SUMMARY

The coevolutionary arms race between hosts and pathogens is often described as a recurrent
struggle for increased resistance in hosts and evasion of recognition by pathogens. These
coevolutionary dynamics dominated by balancing selection lead to the maintenance of allelic
diversity at genes involved in interactions between hosts and pathogens. In plant-pathogen
interactions, the current paradigm posits that the specific defence response is activated upon
recognition of a specific pathogen effector through the corresponding resistance (R) gene in
the host. Numerous studies demonstrated that balancing selection acts on these R genes.
However, little is known about the evolutionary mechanisms shaping other molecules not
directly involved in pathogen recognition, but nevertheless playing an important role in
defence signal activation. In this thesis I investigate the evolutionary forces acting at these
genes in wild tomato species (Solanum sp.).

First, I focus on Rcr3, a ‘guardee’, i.e. target of pathogen effectors secreted by the
fungus Cladosporium fulvum and the oomycete Phytophthora infestans in tomato plants.
Specific activation of the defence response occurs when R genes (the ‘guards’) sense the
modification of the ‘guardee’ by pathogen effectors (‘Guard-Hypothesis’). These interactions
between effector, ‘guardee’ and ‘guard’, are expected to favour contrasting evolutionary
forces acting on the guardee. I study the pattern of sequence evolution and functional
consequences of natural sequence variation on host resistance and show that the evolution of
Rcr3 is characterized by gene duplication, gene conversion and balancing selection in wild
tomato species. Investigating the functional characteristics of 54 natural variants through in
vitro and in planta assays, I reveal differences in the strength of the