Biology subjects

Nordzieke, D. E.

Publications and source records attributed to Nordzieke, D. E..

5 recordsLinked to original sources

bioRxiv2025

Spore type-specific gene expression profiles underlying development and leaf infection processes of Colletotrichum graminicola

Colletotrichum graminicola causes significant losses of the staple crop maize worldwide. The fungus produces two distinct asexual spore types, oval and falcate conidia, which show unique processes in development and plant interaction. Based on genome resequencing of our laboratory strain (CgM2/ M1.001), we investigated the gene expression profiles of oval and falcate conidia during development and early leaf infection using RNA-seq. Our results reveal specific gene expression profiles between the two spore types, indicating fundamental differences in their developmental programs that reflect different modes of infection. We identified expression patterns discriminating both conidia types from mycelium and spore type-specific ones for genes encoding transcription factors, conserved fungal developmental genes, transporters, genes of secondary metabolite clusters, and pathogenicity-related functions, including effectors and carbohydrate-active enzymes (CAZymes). Our study shows that despite the identical genomic basis, oval and falcate conidia show unique transcriptomes across vegetative development and early plant interaction. Taking together, these results provide new insights into the molecular mechanisms determining the biology of C. graminicola and its interaction with the plant host.

microbiology↗

bioRxiv2025

PmaI-dependent pH gradients initiate inter- and intraspecies germling fusion in filamentous fungi

Somatic cell fusion among spore germlings is a complex process in filamentous fungi that enables the formation of a syncytial unit and facilitates the exchange of genetic material apart from sexual reproduction. In this study, we investigated the molecular mechanisms underlying germling fusion in the maize pathogen Colletotrichum graminicola. Based on secretomes harvested during the germling fusion process of fusion-competent oval and fusion-deficient falcate conidia, we identified pH as a communication signal. We showed that the plasma membrane localized ATPase PmaI is a probable source for pH gradient formation. Our results also suggest that the a-pheromone receptor CgSte3 mediates sensing of acidic pH gradients, activating downstream the Cell Wall Integrity Mitogen Activated Protein Kinase pathway. We propose a new model for germling interactions, in which pH serves as an interaction initiation signal, resulting in the activation of the cell-dialogue. Our findings have implications for our understanding of fungal communication and pathogenicity, and highlight the importance of pH as a signal molecule in germling fusion.

microbiology↗

bioRxiv2024

Conserved perception of host and non-host signals via the a-pheromone receptor Ste3 in Colletotrichum graminicola

Understanding the interactions between fungal plant pathogens and host roots is crucial for developing effective disease management strategies. This study investigates the molecular mechanisms underpinning the chemotropic responses of the maize anthracnose fungus Colletotrichum graminicola to maize root exudates. We identify the 7-transmembrane G-protein coupled receptor (GPCR) CgSte3 as a key player in sensing both plant-derived class III peroxidases and diterpenoids. Activation of CgSte3 initiates signaling through the Cell Wall Integrity Mitogen-Activated Protein Kinase (CWI MAPK) pathway, facilitating the pathogens growth towards plant defense molecules. The NADPH oxidase CgNox2 is crucial for peroxidase sensing but not for diterpenoid detection. These findings reveal that CgSte3 and CWI MAPK pathways are central to C. graminicolas ability to hijack plant defense signals, highlighting potential targets for controlling maize anthracnose.

microbiology↗

bioRxiv2024

Microbial two front attack: elaborate root infections by Colletotrichum graminicola oval conidia during maize anthracnose

Most plant pathogenic microorganisms have evolved to infect distinct host tissues. The maize anthracnose fungus Colletotrichum graminicola is known for its ability to invade above-ground tissues with asexual falcate conidia. In addition, C. graminicola produces a second asexual spore type, oval conidia. This study investigates the specific adaptations that make oval conidia suitable for maize root infection, demonstrating that only oval conidia exhibit root pathogen characteristics. These include the ability to germinate in soil and grow chemotropically toward root-secreted molecules. High-performance liquid chromatography/mass spectrometry (HPLC/MS) analyses combined with biological assays indicate that diterpenoids, such as dihydrotanshinone I, are likely responsible for the chemical attraction of C. graminicola. Genetic analysis identified the a-pheromone receptor CgSte3 as responsible for diterpenoid perception by the fungal pathogen. In conclusion, the understanding of maize anthracnose disease must be expanded to include an elaborate root infection cycle by oval conidia.

microbiology↗

bioRxiv2021

Hülle-cell-mediated protection of fungal reproductive and overwintering structures against fungivorous animals

Fungal Hulle cells with nuclear storage and developmental backup functions are reminiscent of multipotent stem cells. In the soil, Hulle cells nurse the overwintering fruiting bodies of Aspergillus nidulans. The genome of A. nidulans harbors genes for the biosynthesis of xanthones. We show that enzymes and metabolites of this biosynthetic pathway accumulate in Hulle cells under the control of the regulatory velvet complex, which coordinates development and secondary metabolism. Deletion strains blocked in the conversion of anthraquinones to xanthones are delayed in maturation and growth of fruiting bodies. Xanthones are not required for sexual development but exert antifeedant effects on fungivorous animals such as springtails and woodlice. These findings reveal a novel role of Hulle cells in establishing secure niches for A. nidulans by accumulating metabolites with antifeedant activity that protect reproductive structures from animal predators.

biochemistry↗