The ASK1 gene regulates the sensitivity of Fusarium graminearum to carbendazim, conidiation and sexual production by combining with β2-tubulin.

β-tubulin, a component of microtubules, is involved in a wide variety of roles in cell shape, motility, intracellular trafficking and regulating intracellular metabolism. It has been an important fungicide target to control plant pathogen, for example, Fusarium. However, the regulation of fungicide sensitivity by β-tubulin-interacting proteins is still unclear. Here, ASK1 was identified as a β-tubulin interacting protein. The ASK1 regulated the sensitivity of Fusarium to carbendazim (a benzimidazole carbamate fungicide), and multiple cellular processes, such as chromatin separation, conidiation and sexual production. Further, we found the point mutations at 50th and 198th of β2-tubulin which caused carbendazim resistance decreased the binding between β2-tubulin and ASK1, resulting in the deactivation of ASK1. ASK1, on the other hand, competed with carbendazim to bind to β2-tubulin. The point mutation F167Y in β2-tubulin broke the intermolecular H-bonds and salt bridges between β2-tubulin and ASK1, which reduced the competitive effect of ASK1 to carbendazim and resulted in the similar carbendazim sensitivities in F167Y-ΔASK1 and F167Y. These findings have powerful implications for efforts to understand the interaction among β2-tubulin, its interacting proteins and fungicide, as well as to discover and develop new fungicide against Fusarium.