Ahmadpour SA, Farokhinejad R, Mehrabi-Koushki M 2017 -Further characterization and pathogenicity of Didymella microchlamydospora causing stem necrosis of Morus nigra in Iran. Mycosphere 8(7), 835-852, Doi 10.5943/mycosphere/8/7/3. AbstractIn the last decade, canker and dieback diseases have caused disease of ornamental and fruit trees of Khuzestan Province in the southwest of Iran. Fourty-eight symptomatic branches and trunks were sampled and a survey was made to identify the probable pathogens, which led to the isolation of the recently established species, Didymella microchlamydospora. A multi-locus DNA sequence based phylogeny, in combination with morphology, was used to characterize seven isolates of this species. Two phylogenetic trees constructed based on the combined sequences of ITS/LSU/tub2 and ITS/LSU/tub2/rpb2 regions showed very little differences, and both trees presented generally consistent relationships among the strongly supported clades. In both of threeand four-locus based phylogenetic trees, our isolates and a reference strain, D. microchlamydospora CBS 105.95, formed supportive monophyletic clades with strong 99% and 100% BS support, respectively. In pathogenicity tests, the isolate of D. microchlamydospora SCUA 14_Dez_Mor formed the necrosis and wood discoloration on stem fragments of Morus nigra. To our knowledge, this is the first report of pathogenicity of D. microchlamydospora on Morus nigra and its association on plants of olive, bitter orange, oleander and bottlebrush worldwide. In addition, we gave a slightly amended description of this species.