Phenotypic and phylogenetic segregation of Alternaria infectoria from small-spored Alternaria species isolated from wheat in Germany and Russia

Abstract

To identify the taxonomic differences between phytopathogenic small-spored Alternaria strains isolated from wheat kernels in Germany and Russia by a polyphasic approach. Ninety-five Alternaria (A.) strains were characterized by their colony colour, their three-dimensional sporulation patterns, mycotoxin production and phylogenetic relationships based on sequence variation in translation elongation factor 1-α (TEF1-α). The examination of toxin profiles and the phylogenetic features via TEF1-α resulted in two distinct clusters, in each case containing Alternaria infectoria isolates (92 and 96% respectively) in the first and the Alternaria alternata, Alternaria arborescens and Alternaria tenuissima isolates (77 and 79% respectively) in the other combined cluster. The production of Alternariol, Altertoxin and Altenuene has not been reported previously in the A.infectoria species group. The isolates from Germany and Russia differ slightly in species composition and mycotoxin production capacity. We identified that the A.infectoria species group can be differentiated from the A.alternata, A.arborescens and A.tenuissima species group by colour, low mycotoxin production and by the sequence variation in TEF1-α gene. These results allow a reliable toxic risk assessment when detecting different Alternaria fungi on cereals.