The Human Drug Auranofin Inhibits the Growth of Xanthomonas oryzae pv. oryzae and Magnaporthe oryzae, Which Cause Rice Leaf Blight and Blast

Pathogen attack and abiotic stress affect grain yields in rice fields worldwide. Rice leaf blast is caused by the fungal pathogen Magnaporthe oryzae, whereas rice leaf blight is caused by the bacterial pathogen Xanthomonas oryzae pv. oryzae (Xoo). Rice leaf blast and blight, the two most destructive diseases in rice, result in huge yield losses. We therefore tried to identify a chemical that could be utilized as an inhibitor of rice leaf blast and blight. Here, we show that both bacterial-induced rice blight and fungal-induced rice blast can be controlled by auranofin, an anti-rheumatoid arthritis and anti-cancer drug used in humans. Auranofin directly inhibited the growth of four Xoo strains, including PXO99, KACC10208, 1209, and 1308. In addition, auranofin effectively controlled the growth of 10 M. oryzae strains, including KACC46531, 46532, 46534, 46535, 46536, 46538, 46540, 46541, 46542, and 46544, although its effect on M. oryzae was weaker than that on Xoo. These results suggest that auranofin can be applied to rice to block both rice leaf blight and blast caused by Xoo and M. oryzae, respectively.