Research

Understanding the central switch in fungal toxin production Molds play a variety of ecological roles on our planet, especially in natural nutrient cycles and as pathogens of plants and animals. Of particular interest is their ability to produce a wide variety of small, bioactive molecules. One example of a very useful molecule is the antibiotic penicillin, which has saved millions of lives to date. But there are also dangerous molecules, such as toxins produced by molds, that can contaminate our food and thereby threaten consumer health. So the final goal must be to precisely understand the molecular and cellular programs in those fungi and thus develop natural solutions against fungal infections. Our previous research has shown that epigenetic processes regulate toxin production, but also a specific kinase - a regulatory protein that can chemically modify other proteins in its environment - plays a decisive role. In a previously unknown way, it is able to transmit a starvation signal in the cell, which ultimately leads to a complete change in the cellular metabolism and thereby activates the genetic machinery for toxin formation. In this project, we are now addressing the question of exactly how the starvation signal is processed by the fungal cell so that mycotoxins are formed. For this, we are using as experimental systems a conventional mold that is present ubiquitously in nature and buildings (Aspergillus) and a fungus that is considered one of the most important pathogens in crop plants worldwide (Fusarium). The entire genetic response of both fungi at the RNA level and at the protein level will be analyzed molecularly, biochemically and bioinformatically during different stages of their life cycles. In addition, those proteins whose function is regulated by the kinase should be identified. In this way, the signaling pathway from nutrient deficiency from the cell surface to the genetic activation of toxin production in two different molds should be elucidated as completely as possible. Ultimately, the results of this research could close a gap in the fundamental understanding of cellular processes during toxin production in mold fungi. This knowledge can then be used to develop new control strategies to ward off plant diseases and prevent biological contamination of food.

Agricultural plant production needs pathogen and pest control, even more so as climate change imposes additional risks through weakening natural defense system of plants and the introduction of novel pathogens into temperate production areas. Moreover, development of pathogen or pest populations that are resistant against commonly used pesticides and toxic effects against non-target organisms and the environment poses additional risks. Especially the use of molecules with the same mode-of-action in medicine and agriculture fosters the spread of cross-resistances. Therefore, novel natural bioactive compounds are needed that should be highly effective and specific to the pathogen or pest target, optimally have more than one mode-of action and at the same time being almost not toxic to other organisms and environment. Traditional searches to find such novel molecules often used microbial sources as these organisms produce a wealth of natural bioactive substances for their own defense or communication. However, over the last decades, few new substances were identified, although genomic analyses of the microbes predicted a much higher chemical diversity than so far retrieved from them. Data originating from our laboratory for the first provided a mechanistic, chromatin-based molecular-genetic explanation for this undiscovered chemical richness. In combination with large-scale genome sequencing of fungi and oomycetes these discoveries provide new technical means for successful genome mining campaigns in fungi that allow a much better exploration of the high chemical diversity of fungi. In this translational science project we propose to use this basic knowledge for the revelation of novel natural bioactive substances from the hidden chemical space of fungi. From previous small-scale screenings and additional preliminary data we have generated already solid proof-of-concept that many novel molecules can be found using this strategy. We propose here to systematically employ chromatin-modifying methods and exploit our large and diverse in-house strain collection in a high-throughput (HTP) screening format. The techniques and infrastructure for this endeavor are available at our institute and the associated BMOSA core-facility (https://boku.ac.at/cf/bmosa).

Academic Abstract “Nitrate Signaling in Fungi” Ecologically, nitrate (NO3-) plays a central role in the global nitrogen cycle and it is the main nitrogenous nutrient for plants. Also archaea, bacteria and fungi utilize nitrate for growth but for fungi it is not known, how the genetic network is activated, that leads to the production of the necessary enzymes. Nitrate is not only an essential nutrient for saprophytic, but also for pathogenic fungi. Based on our previous work with NirA and on a collaboration with an experienced structural biology group we will try to crystallize NirA domains or the whole protein in absence and presence of the inducers, to better understand structure-function relationships. Finally, we plan to perform an unbiased forward genetic screen to identify the enzyme that reduces a crucial regulatory methionine sulfoxide (Metox169) during induction. The mechanism by which nitrate-specific transcription factors are activated is not known for any fungal species. Thus, the results of this project will certainly have impact on our understanding how this ecologically important pathway is regulated.