Molecular characterization of genes regulating fumonisin biosynthesis and development in maize pathogen fusarium verticilliodes

Abstract

Fusarium verticillioides (Sacc.) Nirenberg (teleomorph Gibberella moniliformis Wineland) is a fungal pathogen of maize that causes ear rots and stalk rots worldwide. In addition, it produces a group of mycotoxins called fumonisins when the fungus colonizes maize and maize-based products. Fumonisin B1 (FB1), the predominant form occurring in nature, can cause detrimental health effects in animals and humans. Several efforts were made to study the host and pathogen factors that contribute to the production of fumonisins. Using the available genomic resources, three genes with a potential role in FB1 regulation and development were identified. The genes are GBP1, GBB1 and GAP1. This research describes molecular characterization of these genes with respect to regulation of FB1 and development in F. verticillioides. GBP1 is a monomeric GTP binding protein with similarity to DRG and Obg sub-classes of G-proteins. GBB1 encodes heterotrimeric GTP binding protein β subunit. GAP1 is a GPI (Glycophosphotidylinositol) anchored protein, which belongs to a family of cell wall proteins. Targeted deletion and complementation studies indicated that GBP1 is negatively associated with FB1 biosynthesis but had no effect on conidiation in F. verticillioides. GBB1 plays an important role in regulation of FB1 biosynthesis, conidiation and hyphal growth, but not virulence. GAP1 is associated with growth, development and conidiation but not in positive regulation of FB1 or pathogenicity. The outcome of this study revealed new molecular genetic components that will help scientists better understand signal transduction pathways that regulate FB1 biosynthesis and conidiation in F. verticillioides.