Biology subjects

Poeggeler, S.

Publications and source records attributed to Poeggeler, S..

3 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

Capture of the SmSTRIPAK proxiome identifies the greenbeard proteins SmDOC1/2 as regulators of the MAK2 pathway to control sexual development in Sordaria macrospora

Hyphal fusion and sexual development in filamentous fungi rely on coordinated signaling of numerous conserved nodes such as the striatin interacting phosphatase and kinase (STRIPAK) complex or the pheromone response (PR) MAP kinase cascade (MIK2, MEK2, MAK2, HAM5). Here we used the homothallic ascomycete Sordaria macrospora (Sm) to screen for putative protein interactors of the SmSTRIPAK complex. Using the STRIPAK complex interactor 1 (SCI1) subunit of the complex as bait, we enriched and identified canonical SmSTRIPAK components and a determinant of communication (DOC) protein. The DOC proteins were previously described in the closely related and heterothallic species Neurospora crassa, functioning in allorecognition of germlings and hyphal fusions. We generated {Delta}Smdoc1, {Delta}Smdoc2 single deletion strains and the double deletion mutant {Delta}Smdoc1{Delta}Smdoc2 in S. macrospora. Deletion phenotypes were paradoxical: single knockouts ({Delta}Smdoc1 or {Delta}Smdoc2) were nearly sterile and sexual development was impaired, yet the double mutant ({Delta}Smdoc1{Delta}Smdoc2) exhibited wild-type fertility and development, demonstrating non-redundant and mutually antagonistic roles. Similarly, we demonstrated an impairment of the N. crassa {Delta}doc-2 mutant in sexual development. Using gene tagging at the native locus, we performed TurboID-based proximity mapping with SmDOC1 and SmDOC2 as bait proteins. This proximity mapping demonstrated close ties of SmDOC1/2 to components of the PR MAP kinase pathway and revealed mutual SmDOC1 - SmDOC2 proximity. Yeast Two-Hybrid experiments with SmDOC1 confirmed the direct interaction with the MAP kinases MEK2 and MAK2. Fluorescence microscopy revealed that SmDOC1-TagRFP-T localized to ring-like structures around septal pores. Our results demonstrate that the DOC system is not restricted to heterothallic N. crassa, but also plays an essential role in the development of fruiting bodies in the homothallic fungus S. macrospora. These findings suggest the DOC1/2 proteins as a novel system that integrates STRIPAK and PR pathways, providing a possible mechanistic explanation for their non-additive deletion strain phenotypes.

cell biology↗

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↗