Fungal fludioxonil sensitivity is diminished by a constitutively active form of the group III histidine kinase

► Constitutively active forms of the group III HK confer fludioxonil resistance. ► First direct evidence for inhibition of the group III HK activity by fludioxonil. ► Previously known missense mutations in other group III HKs may be active forms. ► Different mechanisms for fludioxonil resistance by deletion and missense mutations.