A lipophilic cation protects crops against fungal pathogens by multiple modes of action.

Steinberg, Gero; Schuster, Martin; Gurr, Sarah J; Schrader, Tina A; Schrader, Michael; Wood, Mark; Early, Andy; Kilaru, Sreedhar · Nat Commun · 2020

basic_science · Level V

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Abstract

The emerging resistance of crop pathogens to fungicides poses a challenge to food security and compels discovery of new antifungal compounds. Here, we show that mono-alkyl lipophilic cations (MALCs) inhibit oxidative phosphorylation by affecting NADH oxidation in the plant pathogens Zymoseptoria tritici, Ustilago maydis and Magnaporthe oryzae. One of these MALCs, consisting of a dimethylsulfonium moiety and a long alkyl chain (C<sub>18</sub>-SMe<sub>2</sub><sup>+</sup>), also induces production of reactive oxygen species at the level of respiratory complex I, thus triggering fungal apoptosis. In addition, C<sub>18</sub>-SMe<sub>2</sub><sup>+</sup> activates innate plant defense. This multiple activity effectively protects cereals against Septoria tritici blotch and rice blast disease. C<sub>18</sub>-SMe<sub>2</sub><sup>+</sup> has low toxicity in Daphnia magna, and is not mutagenic or phytotoxic. Thus, MALCs hold potential as effective and non-toxic crop fungicides.

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