Research
1. Evolution and Regulation of Resistance Genes in tomatoes.: A major focus of the lab is how disease resistance genes evolve in natural populations and how these genes are regulated. We use comparative genomics to determine the patterns of genetic polymorphism and divergence within and between wild tomato species. The expression of these resistance genes and the correlation of gene expression and open chromatin is also investigated. We link patterns of expression with resistance phenotypes and evolutionary trajectories. Despite the expectation that resistance genes should display signals of adaptive evolution, our studies are revealing that a significant number of NBS-LRRs display strong conservation within and between species. This work is supported by the DAAD and the DFG and facilitated through collaboration with Prof. Bjoern Usadel, Dr. Thomas Hartwig, Dr. Jedrzej Szymanski, Dr. Charles Underwood, and Dr. Simon Zumkeller.
2. The role of gene duplication in adaptation. As part of the TRR 341 “Plant ecological genetics”, we are collaborating with the lab of Prof. Thomas Wiehe (University of Cologne) to understand the role gene duplication may play in adaptation in closely related species of Brassicaceae. This project builds upon extensive comparative genomic resources available for these species and uses theoretical methods to build models of gene duplication and divergence under different selective and neutral scenarios. Hereby we can determine which patterns observed in gene families in natural populations can be explained by strictly neutral processes or if gene family expansion and diversification is driven by natural selection.
3. Biodiversity of microbes living in close association with Arabidopsis sp.: Like humans, plants live in close association with microbes. Some of these are pathogens or opportunists, whereas others are proven to be beneficial to their hosts. In collaboration with Prof. Michael Bonkowski at the University of Cologne, we are investigating the biodiversity of the underexplored lineages of protists living in close association with species of Brassicaceae. To this end, metabarcoding methods for major groups of protists have been tested and improved in our labs. We are currently analyzing how the community composition of oomycetes and cercozoans is differentiated across different plant tissues and the soil substrate. The ultimate goal is to discover novel microbes that are beneficial to their hosts and provide new insights that can be translated into effective crop protection. This work has been supported by Ceplas, the Cluster of Excellence on Plant Science (EXC 1028) since 2012.
4. Evolution of symbiosis genes in Lotus species: We are studying a suite of symbiosis genes in European and Asian species of Lotus. In this project, we combine population genetic studies, phylogenetic studies and functional work to determine the types of selection that have operated on these loci and to understand how natural variation at particular candidate loci affects the interspecific interaction between host and symbiont.
5. The interplay of pathogens, microRNAs, and regulation of resistance gene transcript abundance for rapid evolutionary responses in plants: We are currently investigating the co-evolution between the miR482 gene family and the resistance gene targets within the Solanaceae. Seven miR482 genes are expressed in wild tomatoes and are predicted to negatively regulate approximately 20% of the R-genes in tomato. During infection by Phytophthora infestans, we observe a down-regulation of these miR482 genes in tomato and could document a corresponding up-regulation of their predicted R-gene targets. Since most R-genes are predicted to be targeted by multiple miR482 paralogs, this may result in a degree of redundancy. To what degree the multiple layers of negative control have facilitated the rapid evolution of R-genes in wild plant species is the focus of a DFG funded project on rapid evolution.