اولین گزارش از گونه Neoscytalidium novaehollandiae بر روی درختان بادام، زیتون گردو در ایران

The family Botryosphaeriaceae contains many fungal species, which have been recognized as important pathogens on various crop trees. In order to determine the fungal agents associated with the decline of almond, olive and walnut trees, a survey was conducted in orchards of these crops in Isfahan, Kerman, Fars, Kohgiluyeh and Boyer Ahmad and Qom provinces during 2016-18. Wood samples were collected from affected branches of diseased trees showing dieback, canker and gumming symptoms. Transversal cuts were made from infected branches to record any internal wood discoloration. Fungal isolations were performed from discolored wood tissues. Branches were flame sterilized by spraying with 96% ethanol and passing through a flame. Disinfected segments were then cut longitudinally and small wood chips from the margin between healthy and necrotic wood tissues were aseptically removed with a scalpel and placed onto tetracycline-amended potato dextrose gar (PDA) directly. These plates were incubated in the dark at 25 °C until the emergence of fungal colonies. Seventy-eight isolates of Neoscytalidium were obtained from affected trees. Of these, 24 isolates were isolated from almond (from Isfahan, Kerman, Kohgiluyeh and Boyer-Ahmad provinces), 27 isolates were also obtained from olive trees (from Isfahan, Qom, Kohgiluyeh and Boyer-Ahmad provinces) and 27 isolates were recovered from walnut (from Isfahan, Fars and Kerman provinces). These isolates were initially identified based on morphological and cultural characteristics. Morphological identifications of the selected isolates were confirmed by molecular methods. Total genomic DNA of the isolates was extracted with CTAB (Cetyl Trimethyl Ammonium Bromide) method, and identification of the isolates was confirmed by sequence analysis of the internal transcribed spacer (ITS) nrDNA region and a partial sequence of translation elongation factor 1-α gene (Tef-1a) using the primers pairs ITS1/ITS4 and EF1-688F/EF1-1251R, respectively. Based on morphological and molecular data all these isolates were identified as Neoscytalidium novaehollandiae. According to references review, this is the first report of the presence of this species on almond trees in Iran, and olive and walnut trees in the world.