ITS sequence data and morphology differentiate Cytospora chrysosperma associated with trunk disease of grapevine in northern Iran

Abstract

Abstract Trunk diseases are potential threats for the grapevine industry owing to the worldwide incidence and economic impact of the diseases. Several fungal groups are known to be involved in these diseases. In a survey on grapevine trunk diseases in northern Iran, Cytospora isolates were repeatedly recovered from vines showing decline symptoms. The symptoms appeared as pale brown to brown streaks in longitudinal cuts of shoots. The morphological and cultural characteristics of the isolates were in agreement with the description of Cytospora chrysosperma. Sequence data of the ITS-rDNA region was used to further confirm the identity of the species. Phylogenetic analysis based on the sequence data obtained in this study and the sequences from GenBank, confirmed the morphological identification. Our isolates were clustered together with C. chrysosperma isolates known from other woody host plant species. The pathogenicity assay on detached shoots of grapevines induced the same symptoms as was observed in field conditions. Although, C. chrysosperma is known from several woody hosts in Iran, the occurrence of this species on grapevines showing decline symptoms is new. The economic impact, distribution, and degree of involvement of C. chrysosperma in decline of vines in other regions of Iran remains to be studied.