Carbendazim-resistance associated β2-tubulin substitutions increase deoxynivalenol biosynthesis by reducing the interaction between β2-tubulin and IDH3 in Fusarium graminearum

Abstract

AbstractMicrotubule is a well-known structural protein participating in cell division, motility and vesicle traffic. In this study, we found that β2-tubulin, one of the microtubule components, plays an important role in regulating secondary metabolite deoxynivalenol (DON) biosynthesis in Fusarium graminearum by interacting with isocitrate dehydrogenase subunit 3 (IDH3). We found IDH3 negatively regulate DON biosynthesis by reducing acetyl-CoA accumulation in F. graminearum and DON biosynthesis was stimulated by exogenous acetyl-CoA. In addition, the expression of IDH3 significantly decreased in the carbendazim-resistant mutant nt167 (Fgβ F167Y). Furthermore, we found that carbendazim-resistance associated β2-tubulin substitutions reducing the interaction intensity between β2-tubulin and IDH3. Interestingly, we demonstrated that β2-tubulin inhibitor carbendazim can disrupt the interaction between β2-tubulin and IDH3. The decreased interaction intensity between β2-tubulin and IDH3 resulted in the decreased expression of IDH3, which can cause the accumulation of acetyl-CoA, precursor of DON biosynthesis in F. graminearum. Thus, we revealed that carbendazim-resistance associated β2-tubulin substitutions or carbendazim treatment increases DON biosynthesis by reducing the interaction between β2-tubulin and IDH3 in F. graminearum. Taken together, the novel findings give the new perspectives of β2-tubulin in regulating secondary metabolism in phytopathogenic fungi.Author SummaryThe deoxynivalenol (DON) biosynthesis is increased in carbendazim-resistant strains in Fusarium graminearum. To date, the molecular mechanism between the carbendazim-resistant substitution and the increased DON production remained elusive. Here we found that acetyl-CoA-associated enzyme IDH3 negatively regulates acetyl-CoA and DON biosynthesis. Moreover, β2 tubulin interacted with IDH3 physically and increase its expression. We further found that carbendazim-resistant substitution in β2 tubulin reducing the interaction between β2 tubulin and IDH3, which resulted in the decreased expression of IDH3. In addition, we demonstrated that carbendazim disrupting the binding between β2 tubulin and IDH3, which also decreases the expression of IDH3. Taken together, our results give a newly insights into the mechanism of β2 tubulin and its carbendazim-resistant substitution in regulating DON biosynthesis.