DBG · Promoting young researchers

Rune Hansen (Christian-Albrechts-Universität zu Kiel, CAU)

Rune Hansen's Master thesis was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at xxUniversity in the year 2023 with the title:

Comparative RNASeq analysis of the Aegilops cylindrica – Zymoseptoria tritici pathosystem in compatible and incompatible interactions

Rune Hansen used RNASeq data to generate the first de novo transcriptome assembly of the close wheat relative Aegilops cylindrica during compatible and incompatible interactions with the agriculturally important wheat pathogen Zymoseptoria tritici to identify a potential new source of resistance genes.

Wheat is one of the most important crops for feeding a growing world population. In addition to climate change, the crop is also strongly influenced by the pathogen Zymoseptoria tritici (Ascomycota). In this work, the wild plant Aegilops cylindrica, which is closely related to wheat, was used as a host to perform compatible and incompatible infection experiments with different Z. tritici genotypes. At different time points of infection, some leaves were harvested and their RNA isolated. Using bioinformatic techniques, a de novo transcriptome assembly was generated to search for significantly differentially expressed genes that induce resistance in the incompatible interactions. Surprisingly, many known resistance genes (e.g. leucine rich repeat (LRR)-domain-containing proteins) and resistance-inducing genes (e.g. pathogenesis-related (PR) genes or various transcription factors) were strongly expressed, especially in the compatible interactions, without inducing resistance in the plants at all. During the incompatible interaction, only a few genes were found to be differentially expressed compared to the untreated plants and also differing from the expressed genes of the compatible interactions. Among other resistance gene candidates, a gene coding for a lipid transfer protein seems to be particularly promising. This gene is only downregulated during the compatible interaction. In addition, a transcription factor of the WRKY family was identified that could act as a susceptibility factor during the compatible interaction. In summary, this work illustrates the potential utility of previously unexplored wild plants as a source of new agriculturally important resistance genes and provides a basis for studying the effects of mutations in the newly discovered resistance genes in genetic engineering experiments.

Rune Hansen conducted this work at the Botanic Institute in the working group of Prof. Dr. Eva Stukenbrock.

Micrographs obtained from CLSM (confocal laser scanning microscopy) analysis using maximum projections of confocal image z-stacks. Nuclei and plant tissue are displayed in purple, fungal hyphae are displayed in green. After 12 dpi (days past infection) the incompatible interaction sample only shows infection stage A (hyphal penetration into the stoma). During the compatible interaction infection stages C (fungus forming prepycnidia in the stomatal cavity) and D (pycnidia formation) can be observed. The letters indicate which infection stage is observable.