Fusarium sambucinum astA gene expressed during potato infection is a functional orthologue of Aspergillus nidulans astA

- Fusarium sambucinum pathogen possesses alternative sulfate transporter AstA.
- Heterologous expression of FgastA and FsastA complements sulfate permease deficiency.
- F. sambucinum astA is regulated by sulfur metabolite repression.
- F. sambucinum astA is strongly derepressed during potato infection.

Sulfate assimilation plays a vital role in prototrophic organisms. Orthologues of the alternative sulfate transporter (AstA) gene from Aspergillus nidulans were identified in the fungal plant pathogens Fusarium sambucinum and Fusarium graminearum. By physiological and biochemical analyses, the AstA orthologues were determined to be able to uptake sulfate from the environment. Similarly to astA in A. nidulans, the FsastA gene was found to be regulated by sulfur metabolite repression (SMR) in a sulfur-dependent manner. In contrast, the FgastA transcript was undetectable, however, when the FgastA gene was expressed heterologously in A. nidulans, the translated FgAstA protein acted as a sulfate transporter. Interestingly, F. sambucinum astA expression was remarkably augmented in infected potato tubers, despite the presence abundant sulfate and was found not to be correlated with plant resistance.