CLUSTERING OF TRICHOTHECENE-PRODUCING FUSARIUM STRAINS DETERMINED FROM 28S RIBOSOMAL DNA-SEQUENCES

The genus Fusarium includes several species that produce trichothecene s, We analyzed DNA sequences from a variable region at the 5' end of t he large nuclear ribosomal DNA (rDNA) (28S) to determine the genetic r elatedness of trichothecene-producing Fusarium species, All trichothec ene-producing strains clustered together, and two monophyletic groups were resolved, The first clade included strains of F, acuminatum, F, s ambucinum, F. tumidum, F. compactum, F. camptoceras (red pigment), F. sportotrichioides, and F. venenatum, which produced type A trichothece nes (T-2 toxin, HT-2 toxin, neosolaniol, and diacetoxyscirpenol). The second clade consisted of strains of F. crookwellense, F. culmorum, an d F. graminearum, which produced type B trichothecenes (Fusarenone-X, nivalenol, and deoxynivalenol), The phylogenetic placement of the spec ies based on rDNA correlated better with toxic secondary metabolite da ta rather than with the current classification system based on morphol ogy.