Maize ear rot and moniliformin contamination by cryptic species of Fusarium subglutinans.

Fusarium subglutinans causes maize ear rot and contaminates grain with the mycotoxin moniliformin. Previous DNA sequence analysis divided F. subglutinans from maize into two cryptic species, designated groups 1 and 2. Here, it was determined whether the two groups differ in the agriculturally important traits of virulence on maize and moniliformin production in planta. Thirty-seven strains from U.S. maize were assigned to groups 1 and 2 by DNA sequence analysis. In field tests, all strains were highly virulent on maize inbred B73 and four maize hybrids. In planta, 82% of group 1 strains and 25% of group 2 strains produced high levels (100-1500 microg/g) of moniliformin. All group 2 strains from more northern states produced little or no moniliformin (0-5 microg/g). These data indicate that moniliformin production is highly variable in F. subglutinans from U.S. maize and that production may not be required for the fungus to cause maize ear rot.