Molecular and morphological differentiation of Botryosphaeria dothidea (anamorph Fusicoccum aesculi) from some other fungi with Fusicoccum anamorphs

Differentiation of Botryosphaeria species with Fusicoccum anamorphs has depended on recognition of the anamorphs. This has resulted in some confusion in the taxonomy and our understanding of the pathology of these species because these anamorphs are very similar morphologically and the characters used for differentiation can be influenced by the substrate. We have examined 89 isolates identified by the collectors as B. dothidea. (F. aesculi), B. ribis (Fusicoccum sp.), B. parva (F. parvum), or F. luteum. Cluster analysis of random amplified polymorphic DNA (RAPD) marker data identified three distinct groups, which we have designated Bd (probable B. dothidea), Br (probable B. ribis, but including isolates of B. parva), and Fl (probable F. luteum). Analysis of DNA sequence of the nuclear rDNA ITS region from a subset of isolates from each group supports these relationships. Measurement of conidia from a subset of isolates revealed statistically significant differences in shape that can be used to differentiate between conidia of the Bd group isolates and these of the other groups. Conidia of the Br and Fl group isolates, however were similar. We conclude that B. dothidea can be differentiated from these other fungi with Fusicoccum anamorphs by all three techniques.