Comparative genomics of DNA repair in the Fusarium species complex

Shira Milo-Cochavi 1 Ulrich Guldener 2,3 Yael Almog 1 Shay Covo 1
1Microbiology and Phytopathology, The Hebrew University of Jerusalem, Rehovot, Israel
2Molecular Biology and Biotechnology of Fungi, University of Münster, Münster, Germany
3Institute of Bioinformatics and Systems Biology, German Research Center for Environmental Health (GmbH), Neuherberg, Germany

Fungal plant pathogens are continuously exposed to DNA damage originating from the environment and their host. Even though DNA repair is a fundamental process in all organisms, very little is known about fungal plant pathogen DNA repair machinery. In this research, we focus on DNA damage repair pathways in Fusarium oxysporum (FOL) and Fusarium mangiferae (FMN) which are closely related fungal plant pathogen species that occupy very different ecological niches. To our surprise, we found that FMN, a foliar plant pathogen, is more sensitive to UV than FOL, a soil-borne plant pathogen, while the opposite was true for alkylating agents. Moreover, a few hours exposure to sunlight seem potentially very lethal for FMN spores. However, there was no difference in sensitivity to 4-NQO between the two fungi indicating that nucleotide excision repair is not defected in FMN. The UV-repair specific genes and MMS repair genes are highly conserved between FOL and FMN therefore we hypothesize that the difference stems from gene expression. RNAseq analysis revealed a clear and typical transcriptional response of both FOL and FMN to MMS. Many NER-associated transcripts were induced under MMS in both fungi suggesting that NER might play an important role in protecting FOL and FMN genome from methylating agents. Interestingly, both fungi did not respond to UV-C as expected; there was a significant down regulation of many DNA repair genes including UV-related phr1 and uvde. In conclusion, we aim to identify species-specific DNA damage response signature and suggest that this is a fundamental component in a set of factors that dictate fungal plant pathogen agroecology niche and disease cycle.