Functional analyses of two syntaxin-like SNARE genes,GzSYN1 and GzSYN2, in the ascomycete Gibberella zeae

We identified two syntaxin-like SNARE genes, named GzSYN1 and GzSYN2, from the plant pathogenic ascomycete Gibberella zeae, and characterized the functions and cellular localization of these genes. The GzSYN1 deletion mutant (Δgzsyn1) had 71% reduced hyphal growth compared to the wild-type strain, but produced perithecia with normal ascospores. Δgzsyn2 had the same hyphal growth rate as the wild-type, but completely lost both self and female fertility. When Δgzsyn2 was spermatized for Δmat1-1 or Δmat1-2 strains, it retained its male fertility, but the ascus shape was abnormal and ascospore delimitation was delayed. The Δgzsyn1 and Δgzsyn2 virulence on barley was reduced by 67% and 75%, respectively, compared to the wild-type. The GFP::GzSYN1 fusion protein was localized in vesicles, vacuoles, plasma membranes, and septa, whereas GFP::GzSYN2 was found only in plasma membranes and septa. These results suggest that syntaxins have key roles in fungal development and virulence in G. zeae.