تاکسونومی و بیماریزایی قارچ‌های مرتبط با زوال درختان بلوط در جنگل‌های زاگرس شمالی و مرکزی

Zagros forests with more than 5 million hectares is known as the main forest habitat for oak trees in Iran. Oak decline is one of the serious problems of oak forests all around the world. Decline of oak trees is related with abiotic and biotic factors including fungal plant pathogens. This research was conducted to study the disease symptoms and identification of fungi associated with decline and dieback of oak forests in West Azarbaijan, Kurdistan, Kermanshah, Lorestan and Ilam provinces. During July and September 2016, samples were collected and fungi were isolated and purified using single spore or hyphal tip methods. Morphological characterization of these fungal isolates performed based on colony colour, pigment production on different cultural meda, shape and size of conidiomata, conidiogenous cells and conidia. In order to molecular identification, sequences of LSU (28S nrDNA), ITS, RNA polymerase II second largest subunit (rpb2), and part of the translation elongation factor 1-alpha gene (tef1) and β-tubulin (tub2) gene regions were analyzed. Based on morphological features and phylogenetic analyses, isolates were identified as Cytospora sp. 1, Cytospora sp. 2, Cytospora sp. 3, Kalmusia variispora, Didymella glomerata, Fusarium annulatum, Neocosmospora sp. and Neocosmospora mtavorans. Pathogenicity tests were performed on two year-old Quercus brantii seedlings under greenhouse conditions. The results of pathogenicity tests showed that Fusarium annulatum, Neocosmospora sp. and Neocosmospora metavorans are the most virulent species on oak. After three months, severe dieback and wilting symptoms appeared in inoculated seedlings.