Georgios Tzelepis

I investigate the mechanisms that these pathogenic organisms utilize to overcome the plant immune system, how plants respond to this attack, and how pathogens sense the environment in rhizosphere in order to establish a successful infection. I am also interested in studying how the deglycosylation process of misfolded N-glycoproteins affects fungal physiology and virulence in plant and human pathogens.

Effector proteins in Verticllium longisporum 

Verticillium longisporum is a soil borne pathogen, infecting plants in Brassicaceae family, such as oilseed rape (Brassica napus), cauliflower (Brassica oleracea), turnip (Brassica rapa subsp rapa) etc. This pathogen is responsible for important yield losses worldwide. Any attempt to control this disease has a limited success since this pathogen forms special resting structures, able to survive in soil for a long time and under harsh environmental conditions. Furthermore, no resistant to V. longisporum cultivars have been developed by now. Plant pathogens deploy small-secreted proteins termed as effectors to manipulate plant defense responses. These proteins are usually host even lineage-specific. Our previous data show that V. longisporum contains a certain number of genes encoding putative effector proteins, but nothing is known about their contribution in virulence and pathogenicity. The main questions arisen in this project are:

• How effector proteins are regulated?
• What is their functional role in this pathosystem?
• How do Brassica plants defend themselves against V. longisporum.

 Impact of hybridization in Verticillium longisporum virulence

Hybridization in fungi refers to the process by which two genetically distinct fungal individuals, typically from different strains or species, mate and produce offspring that may exhibit a combination of traits from both parent organisms. Hybridization can increase genetic diversity, which may enhance the ability of fungi to adapt to new environments or ecological niches. Verticillium longisporum is a hybrid species between Verticillium dahliae and an uknown species. It has undergone a loss of its capacity to infect a broad range of hosts in comparison with its parental species, and has specialized exclusively to the Brassicaceae family. In this project we study how hybridization in Verticillium species affects the genome structure in relation to host specificity.

In close cooperation with researchers at Stockholm University, we investigate the genome complex and the population structure of Verticillium longisporum. 

The N-glycoprotein quality control in filamentous fungi

Eukaryotic cells produce a huge amount of proteins; the majority of them are glycoproteins, which are proteins contain a sugar chain (N-glycan). N-glycans play a significant role in protein function and stability, protecting them from proteolysis, facilitating the protein folding and secretion, affecting the protein solubility and the protein localization in the cells. It is also known that N-glycoproteins are structural componets of plasma membranes and fungal cell wall. When proteins consistently fail to be folded properly a are retrotranslocated to cytosol for further degradation by the ERAD pathway. 

We investigate the mechanisms that filamentous fungi deploy in order to cope with ER stress caused by accumulation of misfolded glycoproteins. Our previous results showed that these organisms possibly utilize different mechanisms as compared to mammalian cells and to yeasts. This project is in close collaboration with scientists at RIKEN Institute in Japan.

I am course leader in the following courses:

• Plant Pathology (BI1456-10 ECTS)- MSc level, SLU                                          
• Parasitology, Mycology and Clinical Infection Biology (3MK012-3ECTS) (Mycology part)- MSc level, Uppsala University.
• Mycology basics and applications (4 ECTS)- PhD level, SLU

I have co-supervised five PhD students and eleven graduate and undergraduate students at SLU and Wageningen University.

• Senior lecturer (May 2024- till now): Deparment of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
• Associate senior lecturer (October 2019- May 2024):Deparment of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
  Researcher (2017 - 2019):Swedish University of Agricultural Sciences, Department of Plant Biology.
• Guest Researcher (2017-2018): Wageningen University, Laboratory of Phytopathology, the Netherlands.
• Post-Doctoral fellow (2015 - 2017): Swedish University of Agricultural Sciences, Department of Plant Biology, Uppsala BioCenter, Linnean Center for Plant Biology. 

1. Rafiei V, Dixelius C, Tzelepis G. (2025). The soilborne fungus Verticillium longisporum and its interactions with the Brassicaceous hosts. Molecular Plant Microbe Interactions. https://doi.org/10.1094/MPMI-03-25-0029-IRW .
2.  Piombo E*, Tzelepis G*, Ruus AG, et al. (2024) Sterol regulatory element-binding proteins mediate intrinsic fungicide tolerance and antagonism in the fungal biocontrol agent Clonostachys rosea IK726. Microbiological Research 289:127922. *equal contribution.
3. Piombo E, Vetukuri R, Tzelepis G, Jensen Funck D, Karlsson M, Dubey M (2024). Small RNAs: A new paradigm in fungal-fungal interactions used for biocontrol. Fungal Biology Reviews.48:100356.
4. Sofianos G., Piombo E., Dubey M., Karlsson M., Karaoglanidis G., & Tzelepis, G. (2024).Transcriptomic and functional analyses on a Botrytis cinerea multidrug-resistant (MDR) strain provides new insights into the potential molecular mechanisms of MDR and fitness. Molecular plant pathology, 25(9), e70004. https://doi.org/10.1111/mpp.70004.
5. Rafiei V, Vélëz H, Piombo E, Dubey M, Tzelepis G (2023). Verticillium longisporum phospholipase VlsPLA2 is a virulence factor that targets host nuclei and modulates plant immunity. Molecular Plant Pathology 24:1078-1092. 
6. Rafiei V, Vélëz H, Dixelius C, Tzelepis G (2023).Advances in molecular interactions on the Rhizoctonia solani-sugar beet pathosystem. Fungal Biology Reviews 44: 100297.
7. Rafiei V., Ruffino A., Persson Hodén C., Tornkvist A., Mozuraitis R., Dubey M., Tzelepis G. (2022). A Verticillium longisporum pleiotropic drug transporter determines tolerance to the plant host β-pinene monoterpene. Molecular Plant Pathology. 23: 291-303.
8. Rafiei V., Velez H., Tzelepis G. (2021). The role of glycoside hydrolases in phytopathogenic fungi and oomycetes virulence. International Journal of Molecular Sciences. 22:9359.
9. Samaras A., Karaoglanidis G., Tzelepis G. (2021). Insights into the multitrophic interactions between the biocontrol agent Bacillus subtilis MBI 600, the pathogen Botrytis cinerea and their plant host. Microbiological Research 248, 126752. 
10. Tzelepis G., Dölfors F., Holmquist L., Dixelius C. (2021). Plant mitochondria and chloroplasts are targeted by the Rhizoctonia solani RsCRP1 effector. Biochemical and Biophysical Research Communications 544, 86–90.
11. Tzelepis G. and Karlsson M. (2020). The fungal chitinases. Encyclopedia of Mycology, (eds) Elsevier, pp 23-31. 
12. Charova, S., Dölfors, F., Holmquist, L., Moschou, P., Dixelius, C., Tzelepis, G. (2020). The RsRlpA Effector Is a Protease Inhibitor Promoting Rhizoctonia solani Virulence through Suppression of the Hypersensitive Response. International Journal of Molecular Sciences 21: 8070.
13. Tzelepis G., Persson-Hodèn K., Fogelqvist J., Åsman A., Vetukuri R.R., Dixelius C. (2019). Dominance of mating type A1 and possible epigenetic effects during mating in Phytophthora infestans. Frontiers in Microbiology 11:252.
14. Dolfors F., Holmquist L., Dixelius C., Tzelepis G. (2019). A LysM effector protein from the basidiomycete Rhizoctonia solani contributes to virulence through suppresion of chitin-triggered immunity. Molecular Genetics and Genomics. 294: 1211-1218.
15. Tzelepis G. and Karlsson M. (2019). Killer toxin-like chitinases in filamentous fungi: Structure, regulation and potential roles in fungal biology. Fungal Biology Reviews. 33: 123-132.
16. Fogelqvist J., Tzelepis G., Bejai., Ilbäck J., Schwelm A. and Dixelius C. (2018).  Analysis of the hybrid genomes of two field isolates of the soil- borne fungal   species Verticillium longisporum. BMC Genomics. 19:14.
17. Tzelepis G., Karlsson M. and Suzuki T. (2017). Deglycosylating enzymes acting on N-glycans in fungi: Insights from genome survey. BBA General Subjects, 1861:2551–255.
18. Wibberg D., Andersson L., Tzelepis G., Rupp O. et al. (2016). Genome analysis of the sugar beet pathogen Rhizoctonia solani AG2-2IIIB revealed high numbers in secreted proteins and cell wall degrading enzymes. BMC Genomics, 17:245.
19. Tzelepis G., Dubey M., Jensen D. F and Karlsson M. (2015). Identifying glycoside hydrolase family 18 genes in the mycoparasitic fungal species Clonostachys rosea. Microbiology-Sgm, 161: 1407-1419.
20. Karlsson M., Brandström-Durling M., Choi J., Lackner G, Tzelepis G., et al (2015). Insights on the evolution of mycoparasitism from the genome of Clonostachys rosea. Genome Biology and Evolution. 7 (2): 465-480.
21. Tzelepis G., Hosomi A., Hossain J.T., Hirayama H., Dubey M., Jensen D. F., Suzuki T. and Karlsson, M. (2014).  Endo-β-N-acetylglucosamidases (ENGases) in the fungus Trichoderma atroviride: Possible involvement of the filamentous fungi-specific cytosolic ENGase in the ERAD process. Biochemical and Biophysical Research Communications 449: 256-261.
22. Tzelepis G., Melin P, Jensen D. F, Stenlid J. and Karlsson M. (2012). Functional analysis of glycoside hydrolase family 18 and 20 genes in Neurospora crassa. Fungal Genetics and Biology. 49: 717-730.

https://scholar.google.com/citations?user=qXzsE6QAAAAJ&hl=en  

https://www.researchgate.net/profile/Georgios-Tzelepis?ev=hdr_xprf

https://loop.frontiersin.org/people/802425/overview