RELATIONSHIP BETWEEN AGGRESSIVENESS AND VEGETATIVE COMPATIBILITY OF ISOLATES OF FUSARIUM GRAMINEARUM, AND THEIR ABILITY TO PRODUCE ERGOSTEROL AND MYCOTOXINS IN RICE CULTURE

摘要

A set of 16 isolates of Fusarium graminearum showed a broad range of aggressiveness and were highly diverse in terms of vegetative compatibility grouping (VCG). They also showed wide variability in terms of growth rate, and ergosterol and mycotoxin production in rice culture. One isolate from soil in the United Kingdom produced no perithecia in culture, had a slow growth rate, produced low levels of ergosterol, and no mycotoxins. This isolate is presumed to be F. pseudograminearum, formerly Group 1 F. graminearum. Two inoculation methods, single-floret injection and spray, were used to screen four wheat varieties for reaction to F, graminearum. The methods were correlated over all isolates, but when analyzed by variety, the methods were only correlated for the most susceptible cultivar tested, Using nitrate nonutilizing mutants, the 16 isolates were grouped into 15 VCGs. The two isolates in the same VCG were from corn in Ontario, Disease severity resulting from spray inoculation was correlated with growth rate and ergosterol levels. Deoxynivalenol, the main tricothecene produced by F. graminearum, was correlated with 3 ADON and nivalenol production but not with 15 ADON. Disease severity, growth rate, and ergosterol production were not related to mycotoxin development.