Abstract

The anti-mitochondrial antifungal hypothesis implies a link between mitochondrial activity, fungal fruiting structures and susceptibility towards mitochondrial inhibitors. Here it is shown that the oomycete, Phytophthora nicotianae fits the hypothesis. Fruiting structures (zoosporangia) of this oomycete showed increased beta (β)-oxidation when probing levels of 3-hydroxy fatty acids (3-OH oxylipins) with specific polyclonal antibodies. In addition, increased mitochondrial activity was also observed in the zoosporangia when the mitochondrial transmembrane potential (Δψ_m) probe, Rhodamine 123 was added to the culture. This indicates increased mitochondrial activity in the zoosporangia when compared to the hyphae. When the anti-mitochondrial drug acetylsalicylic acid (ASA) was added to cultures of this oomycete, the zoosporangia were, as expected, most susceptible and were drastically inhibited in the presence of 1 mM of this compound. Similar ASA inhibition results were recorded for P. citrophthora. It is concluded that anti-mitochondrial compounds may find application in combating these devastating plant pathogens and that urgent further research is needed in this direction. 

Key words: Acetylsalicylic acid, antifungal, anti-mitochondrial, asci, Phytophthora, plant pathogen.