Poster: Molecular & Cellular Plant-Microbe Interactions: MPMI
Expression of the FST1 from Fusarium verticillioides in a yeast strain lacking a major myo-inositol transporter gene
C. NIU (1), G. Payne (2), C. Woloshuk (3) (1) Purdue University, U.S.A.; (2) North Carolina State University, U.S.A.; (3) Purdue University, U.S.A.
Fusarium verticillioides causes an important seed disease on maize and produces fumonisin B1 (FB1), a mycotoxin that is detrimental to human and animal health. Previous studies discovered that expression of FST1 is required for FB1 production. In addition, strains lacking a functional FST1 are less virulence on maize seeds and more inhibited by hydrogen peroxide than the wild-type strain. The mutation also causes reduced hydrophobicity of hyphae and macroconidia production. FST1 encodes a putative protein with 12 transmembrane domains with sequence similarity to hexose transporters. However previous studies have failed to prove its ability to transport glucose, fructose or mannose. In this research, we used an Saccharomyces cerevisiae strain lacking a functional myo-inositol transporter (ITR1). This strain grows poorly in myo-inositol medium and is not inhibited by increasing concentrations of FB1. Expression of FST1 in the itr1 mutant restored growth on myo-inositol medium and the inhibitory effects of FB1 to levels observed in the wild-type yeast strain. These results indicate that FST1 can function as a myo-inositol transporter. The evidence also suggests that FST1 can transport FB1 in to the fungal cell.