Differentiation of Alternaria infectoria and Alternaria alternata based on morphology, metabolite profiles, and cultural characteristics

Some small-spored species belonging to the genus Alternaria Nees have been studied according to their chemical, morphological, and cultural characteristics. A data matrix was constructed based on a combination of characters. Cluster analysis of the combined data set showed good resolution of two groups of small-spored Alternaria: the Alternaria infectoria group and the Alternaria alternata group. Isolates in the A infectoria group produced only unique metabolites of unknown identity, whereas all isolates in the A. alternata group produced alternariol and alternariol monomethyl ether. Furthermore, the analysis showed that the A. alternata group and A. infectoria group each could be subdivided into three groups. The colour of fungal colonies on dichloran rose bengal yeast extract sucrose agar was another useful character to differentiate between the A. infectoria and A. alternata groups.