New species and new findings of phoma-like fungi (Didymellaceae) associated with some Asteraceae in Russia

Abstract

The notable difficulties in the morphological identification of phoma-like fungi have resulted in a poor understanding of the generic and species boundaries in this group of organisms. In most available mycofloristic and phytopathological studies, there is no reliable information on the distribution of certain nonspecialized phomoid species on cultivated crops or wild plants. Both the revision of existing data on the biodiversity and geographical distribution of phoma-like fungi associated with Asteraceae in Russia and the acquisition of new knowledge according to modern concepts of these fungi are therefore of great significance. The aim of this study was to identify phoma-like strains from Asteraceae based primarily on phylogenetic analyses of the sequences of four loci (ITS, LSU, TUB, RPB2) as well as on traditional morphological approaches. The resulting phylogenetic trees revealed six well-supported monophyletic clads corresponding to six genera in the family Didymellaceae: Ascochyta, Boeremia, Didymella, Neoascochyta, Nothophoma, and Stagonosporopsis. The isolates were identified as As. kamchatica, B. exigua, B. exigua var. forsythiae, B. exigua var. linicola, D. americana, D. glomerata, D. macrophylla, D. pinodella , D. pomorum, D. rosea, Ne. desmazieri, Ne. paspali, No. quercina, St. dennisii, and St. inoxydabilis. Ascochyta kamchatica sp. nov. was described as a new species. Three Didymella species ( D. pinodella from Cirsium arvense, D. rosea from Sonchus arvensis, and D. macrophylla from Taraxacum officinale), two Neoascochyta species (Ne. desmazieri from T. officinale and Ne. paspali from Achillea millefolium) and St. dennisii from T. officinale were the first records of these phoma-like fungi in Russia.