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Poster

Session: Session 2 Presenting Authors at Posters (Evens)

P-094 - Pathogen-specific transcription factors regulate a secondary metabolism biosynthesis gene cluster necessary for pathogenicity

Thursday, July 17, 2025
13:30 - 15:15  
Location: Confex Hall 3
Discrimination of friend from foe
Colletotrichum tofieldiae (Ct) is a root-associated fungus with diverse lifestyles. Ct3 is pathogenic, whereas its most closely related strain Ct4 is mutualistic on Arabidopsis thaliana. This is at least partly driven by a difference in expression level of a secondary metabolism biosynthesis gene cluster (ABA-BOT), which is only expressed in Ct3. ABA-BOT is regulated at least partly by BOT6, a transcription factor. However, BOT6 is present in both Ct3 and Ct4, so there must be some other factors that regulate BOT6 such that expression of ABA-BOT is activated only in Ct3. Therefore, we sought to uncover the regulatory mechanisms of ABA-BOT in Ct3. To approach this, we first identified the genes uniquely upregulated in Ct3 or Ct4, which were enriched in transcription factors. We then generated knock-out mutants of these genes and screened their in planta phenotypes. As a result, we found two transcription factors that attenuate or contribute to Ct3 virulence in a phosphate-dependent or -independent manner. In particular, both transcription factors seem to be capable of regulating ABA-BOT and BOT6. Interestingly, while ABA-BOT seems to be horizontally transferred, the transcription factors we identified appear to be vertically inherited. We are now in the process of characterizing these transcription factors. This work will ultimately lead to a more robust understanding of the determinants of pathogenicity and the molecular mechanisms that distinguish pathogens from mutualists.