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

Abstract

Microtubule is a well-known structural protein participating in cell division, motility and vesicle traffic. In this study, we found that {beta}2-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 (Fg{beta} F167Y). Furthermore, we found that carbendazim-resistance associated {beta}2-tubulin substitutions reducing the interaction intensity between {beta}2-tubulin and IDH3. Interestingly, we demonstrated that {beta}2-tubulin inhibitor carbendazim can disrupt the interaction between {beta}2-tubulin and IDH3. The decreased interaction intensity between {beta}2-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 {beta}2-tubulin substitutions or carbendazim treatment increases DON biosynthesis by reducing the interaction between {beta}2-tubulin and IDH3 in F. graminearum. Taken together, the novel findings give the new perspectives of {beta}2-tubulin in regulating secondary metabolism in phytopathogenic fungi.\n\nAuthor 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, {beta}2 tubulin interacted with IDH3 physically and increase its expression. We further found that carbendazim-resistant substitution in {beta}2 tubulin reducing the interaction between {beta}2 tubulin and IDH3, which resulted in the decreased expression of IDH3. In addition, we demonstrated that carbendazim disrupting the binding between {beta}2 tubulin and IDH3, which also decreases the expression of IDH3. Taken together, our results give a newly insights into the mechanism of {beta}2 tubulin and its carbendazim-resistant substitution in regulating DON biosynthesis.