Phoma-like Fungi Associated with Convolvulaceae Plants.

Didymellaceae is one of the largest families of the order Pleosporales and includes the main genera of Phoma-like fungi, namely, Ascochyta, Didymella, Stagonosporopsis, etc. Certain wild plants of the family Convolvulaceae plants are among the most harmful weeds and act as an exceptional source of biodiversity of Phoma-like fungi, including Didymellaceae species. Reliable and correct species identification in Phoma-like fungi is only possible in the context of the Consolidated Species Concept (CSC), by combining molecular phylogenetic, micromorphologcial, and cultural features. Leaves of Convolvulaceae weeds with signs of spot diseases were collected during a long-term phytosanitary monitoring of industrial crop fields and natural and ruderal areas. More than 200 isolates of Phoma-like fungi were isolated in pure cultures. Of these, 28 strains preliminarily identified as Didymellaceae species were selected. The objective of this work was to identify the strains according to the CSC. A multilocus phylogenetic analysis was based on the nucleotide sequences of internal transcribed spacer (ITS) and large-subunit (28S) rDNA, the tub2 β-tubulin gene, and the rpb2 gene for the second-largest subunit of RNA polymerase II. The strains were assigned to 18 Didymellaceae species, including Ascochyta erotica, Didymella americana, D. bellidis, D. glomerata, D. macrostoma, D. pomorum, D. pseudomacrophylla, D. segeticola, D. sinensis, D. tanaceti, Epicoccum convolvulicola, E. pseudoplurivorum, Nothophoma brennandiae, N. gossypiicola, Phomatodes nebulosa, Stagonosporopsis caricae, S. heliopsidis, and S. inoxydabilis. All of the species were for the first time detected on plants of the Convolvulaceae family. Seven species (D. bellidis, D. segeticola, D. sinensis. D. tanaceti, N. brennandiae, P. nebulosa, and S. caricae) were for the first time detected in Russia. Stagonosporopsis heliopsidis was for the first time found in Kazakhstan. In addition to detailed phylogenetic data, detailed descriptions of the cultural and micromorphological features of the species are provided in the article.