Submitted to: National Fusarium Head Blight Forum
Publication Type: Abstract Only
Publication Acceptance Date: 12/7/1999
Publication Date: N/A
Technical Abstract: Gibberella zeae (Fusarium graminearum) causes both wheat ear blight and maize ear rot, with yield reduction and mycotoxin contamination of the infected grain. During routine experiments to produce and regenerate protoplasts of G. zeae field strain GZ3639, we identified a mutant, designated ear- for ear rot, that was significantly reduced in ability to cause both wheat ear blight and maize ear rot. Ear- mutants produced normal macroconidia and were similar to the wild-type strain in growth and morphology on V8-juice agar medium but were reduced in pigmentation on a range of other media. Ear- mutants were unable to produce perithecia but were able to function as males in outcrosses with strain GZ3639. To conduct genetic analysis, strains were marked with different auxotrophic mutations, and heterozygous perithecia were identified by the presence of recombinant prototrophic progeny. Among random ascospores from heterozygous perithecia, 48 ear+ and 26 ear- progeny were recovered, a slight deviation from the 1:1 segregation ratio expected for a single gene. Among these progeny, reduced pigmentation and female sterility showed perfect cosegregation with reduced virulence on wheat ears. These data suggest that a single genetic change may affect both morphogenesis and virulence of G. zeae. Future work will elucidate the genetic basis of this mutation and the function of the gene products in wheat ear blight and maize ear rot.