Lightning talk + Poster Australasian Extracellular Vesicles Conference 2020

Preliminary investigations of extracellular vesicles from the fungal wheat pathogen Zymoseptoria tritici (#42)

Erin H Hill 1 , Peter S Solomon 1
  1. The Australian National University, Acton, ACT, Australia

Extracellular vesicles (EVs) have emerged as a potential non-classical secretion mechanism in plants and fungi. Recent evidence suggests EVs may be involved in plant—pathogen interactions, particularly in plant immune responses. Little is known of fungal plant pathogen EVs – do fungal plant pathogens secrete EVs and do they play a role in pathogenesis? We are investigating EVs from the fungal wheat pathogen Zymoseptoria tritici, the causative agent of Septoria Tritici Blotch (STB). This disease poses a significant threat to wheat production in Europe and Australia, yet our understanding of the pathogen and its mechanisms of infection are poorly understood. Z. tritici is an apoplastic pathogen that colonises the extracellular space of wheat leaves during a long asymptomatic period of infection. Given this, the apoplast is likely an important site for molecular host-pathogen interactions but we do not understand how these molecules, particularly those associated with pathogenicity, are exchanged between the two organisms. We hypothesise EVs may play a role in mediating these exchanges between Z. tritici and its host and have begun examining EVs secreted in vitro. Putative EVs have been isolated from axenic fungal cultures using ultracentrifugation. Transmission electron microscopy and nanoparticle tracking analysis suggest these structures resemble fungal EVs described in the literature: EVs vary in size, with most between 50 – 300 nm in diameter. We are currently using bottom up proteomics to explore the protein cargo of in vitro-produced EVs. This molecular characterisation will provide a foundation from which to isolate EVs in planta from Z. tritici-infected wheat. This is one of the first investigations of EVs from a wheat pathogen and we anticipate it will provide initial clues about the role of EVs in the Z. tritici—wheat interaction and more broadly, how fungal plant pathogens communicate with their hosts during infection.