Poster Presentation Science Protecting Plant Health 2017

Sustainable agrichemicals derived from the endophytic fungus Daldinia sp. (#157)

Ross Mann 1 , Christian Krill 1 , Desmond Auer 1 , Mofakhar Hossain 1 , Simone Rochfort 1 2 , Jacky Edwards 1 2 , German Spangenberg 1 2
  1. Agriculture Victoria, AgriBio, Centre for AgriBioscience, Bundoora, Victoria, Australia
  2. School of Applied Systems Biology, La Trobe University, Bundoora, Victoria, Australia

Endophytic fungi have been identified as a unique source of novel biocides, and as such represent an exploitable resource for the discovery of new agrichemicals.  A bioprospecting program was established at Agriculture Victoria to isolate and identify biocidal endophytic fungi, characterise their metabolome, and identify novel biocides with agricultural application.  Permits and agreements were established between the relevant states (Northern Territory and Victoria) and authorities to facilitate the research. 

Daldinia sp. was isolated as an endophytic fungus from Pittosporum biocolor (Banyalla).  In vitro bioassays demonstrated that Daldinia sp. had high biocidal activity against insect pests (Tribolium casteneum) and fungal pathogens (Alternaria alternata, Botrytis cinerea, Rhizoctonia cerealis).  Solid-Phase Microextraction Gas Chromatography – Mass Spectrometry  identified a number of potential biocidal volatile organic compounds (VOCs) in the volatolome of Daldinia sp. A number of these compounds were evaluated in isolation and combination for their biocidal activity against insect pests (T. castaneum), bacterial pathogens (Pseudomonas syringae) and fungal pathogens (Fusarium verticillioides). From the compounds tested, isovaleraldehyde, 3-proponol and acetoin emerged as the most promising candidates for novel agrichemicals.

Isovaleraldehyde, 3-proponol and acetoin are common flavour and fragrance agents, approved for use in foods for human consumption (e.g. GRAS) by the Food and Drug Administration (FDA, USA). Hazard statements indicate that these compounds do not pose a risk to humans (no acute toxicity, carcinogenicity) or the environment (no environmental contamination).  Their physical properties indicate that they are moderately volatile, with short substantivity (24 – 97 hrs).  As such, these compounds represent promising candidates as topical biocides (e.g. treatment of parasites of livestock), oral biocides (e.g. treatment of scours of livestock) or disinfectants (e.g. sterilisation of dairies).