Molecular evolution of plant defence in wild tomato species

Understanding the adaptation of plants to pathogens is of vital importance to create durable resistance in crops. Therefore, we are interested in understanding the evolution of pathogen resistance in relatively short time scales. We study different populations from a diverse and geographically differentiated tomato species, Solanum chilense. We have shown that populations show different levels of defence against a range of pathogens and also show patterns of differential selection for defence-associated genes. We also showed that interspecific variation in the resistance exists within populations. We now want to link these observations to the molecular defence mechanisms involved. In this project, we test the differences in early defence responses between plants and try to identify the causal genes. This way we learn, not just more about the diversity of pathogen defence mechanisms in plants, but might also identify new genes underlying these responses. This project is done in collaboration with Dr. Karin Kleigrewe, BayBioMS and Prof. Corinna Dawid,

This project is funded through SFB924

Pathogen evolution

SPiRaSOL: Sampling Phytophthora Infestans and Ralstonia spp from wild solanum

Besides getting a good understanding of how plants evolve to fend off their pathogens, it is equally important to understand how pathogens evolve to maintain their virulence on plants.
This small, exploratory project in collaboration with Dr. Philippe Prior and Dr. Hannele Lindqvist-Kreuze focused on optimising sampling methods for two very important pathogens on potato and tomato in the field. We focus on sampling methods for various wild Solanum species. Two visits to Peru have taught us a lot about the local field circumstances, the different wild tomato species and their pathogen symptoms. Unfortunately, Philippe passed away in November 2018, leading to an early termination of the project. It has found a follow up in the DFG project below.

This project was funded through the Agropolis Fondation

Pathogen adaptation to host and climate

The wild tomato species Solanum chilense grows in southern Peru and northern Chile and covers a wide range of habitats from the coast and central plains (1500-2000 m altitude) to truly mountainous  terrain (>2500 m altitude). In this project we look at the occurrence of different phytopathogens and their genetic make up throughout the whole species range of S. chilense, to understand how specific pathogens adapt to host and climate. This project is a collaboration with Prof. German Sepulveda at the University of Tarapaca in Chile and  Soledad Gamboa and the CIP, Lima in Peru.

This project is funded through the German Science Foundation

Population genomics of Ramularia collo-cygni

Ramularia collo-cygni is a recently emerging pathogen on Barley. It has only been really noticed as a pathogen  since the mid 1980s, partly due to the difficulty to distinguish it from other stresses in the field and because of its long latent phase.
This project, was a collaboration with Dr Michael Heß, Prof. Ralph Hückelhoven, Dr Martin Münsterkötter and Dr Ulrich Güldener, aims at unraveling the genomic diversity of Ramularia collo-cygni in the field in order to understand which factors contribute to its recent emergence as a pathogen on Barley. Initial invesitigions focused on creaing a useful reference genome. In a second part we analysed 20 strains of the pathogen from a global collection. We found that the pathogen globally intermixed (due to shipping of contaminated seeds) and possibly capable of sexual reproduction. Many Ramularia collo-cygni strains show signs of fungicide resistance. Our findings thus suggest that the current epidemic might grow much larger, of we don’t find clever ways to combat this pathogen.

This project was in part funded through BayKlimaFit

Pathogen diversity in the field

Two additional projects in the lab focus on assessing genetic diversity in the field. The first is in collaboration with Dr Hans Hausladen. This project focuses specifically on the evolution of fungicide resistance in the pathogen Alternaria solani on potato in Europe.

Finally, we also have industry-funded projects, looking at pathogen diversity of important crop pathogens.

 

Other projects

Gene family evolution

Defence responses in plants are governed by large resistance gene families, such as the NLR gene family or the RLP gene family. The lab has a long standing interest in these gene families and several site projects and ongoing collaborations investigating the evolution of these gene families in different plant species. We have for example studied NLR genes in Solanum penellii, and Solanum chilense. In collaboration with Prof. Jonathan Jones, we are looking into NLR evolution in another wild solanum species, Solanum americanum.

The lab also has an interest in RLP genes. We have investigated general patterns in order to distinguish RLPs with defence-associated functions from RLPs with roles in development. We also studied the RLPs in our wild tomato species S. chilense. This study, in collaboration with Matthieu Joosten, found a significantly larger amount of diversity to be present in the species that we originally anticipated. We are currently developing a collaboration with Dr Giuseppe Andolfo to look deeper in RLP diversity in different tomato species.