Summary
Circumventing the emergence of fungicide-resistant strains is a crucial issue for robust disease management in agriculture. The agricultural fungicide ferimzone has been used for the control of rice diseases including rice blast. The emergence of ferimzone-resistant strains in rice fields has not been reported. Here, we identified the copper transport
CoICT1
gene as the ferimzone sensitivity gene in
Colletotrichum orbiculare
and the rice blast fungus
Magnaporthe oryzae
. Genetic and cytological analyses showed that functional defects in the copper transport pathways, consisting of CoIct1 and P-type ATPase CoCcc2, led to the low sensitivity to ferimzone and the pathogenicity defect due to attenuated melanization in the appressorium. Importantly, the presence of CuSO
4
induced high sensitivity to ferimzone even in the
coict1
mutant. Our study shows that there is a trade-off relation between the sensitivity to ferimzone and fungal pathogenicity.