Morphological and molecular identification of Cytospora chrysosperma causing canker disease on Prunus persica

Abstract

Peach (Prunus persica) is one of the most valuable fruit trees around the world including Iran. During spring and summer 2016, severe branch dieback and canker was observed on peach trees in Hamadan province, Iran. The cankered peach twigs contained fruiting bodies of the fungus. It was estimated that 58% of peach trees were severely damaged by this disease. A fungus was consistently isolated from infected tissues. Morphological and cultural characteristics, as well as the sequences of the ITS and β-tubulin regions and pathogenicity tests, showed that the causal agent of disease was Cytospora chrysosperma. It was already reported that C. chrysosperma caused severe losses on a wide range of plant hosts worldwide. However, to our knowledge, this is the first report of C. chrysosperma on P. persica in the world and Iran.Keywords Its . β-tubulin . Cytospora chrysosperma . Prunus persica Peach (Prunus persica) is an economically important deciduous tree belonging to the Rosaceae family producing 20 million tons of fruit per year worldwide. It is one of the most important fruit trees around the world including Iran. The peach orchards with dieback and canker symptoms were observed during spring and summer 2016, in Hamadan province of Iran. The symptoms included wood lesions and cankers with fruiting bodies from fungus (Fig. 1a). 15 orchards were assessed from five different regions of Hamadan province and 80 trees out of 137 inspected trees displayed typical symptoms of disease. It was estimated that 58% of peach trees were severely damaged by this disease. In order to identify the causal agent of the disease, a total of 80 diseased twigs were collected from symptomatic trees. Small pieces, approximately 0.5 cm 3 , were cut from the edge of diseased and healthy tissues and sterilised in 70% ethanol for 1 min, followed by washing with sterile distilled water and dried on sterile filter paper. The plant segments were then placed on the surface of Potato Dextrose Agar (PDA) medium and incubated at 25°C in the darkness. Purification was done from three-day-old isolates by the mycelium tip culture technique and also in some cases, the single-spore technique was made using Adams et al. (2006) method. The cultures were preserved on PDA in 2 ml microtube slants at 4°C in the Culture Collection of the Bu-Ali Sina University of Iran and a culture of C. chrysosperma (CYH1) isolate was also deposited in the Iranian Research Institute of Plant Protection Culture Collection (IRAN 2642C).The morphological characteristics were determined based on pure cultures grown on PDA. Conidiomata were examined on infected twigs, the structure and size of fruiting bodies, presence or absence of a conceptacle, and size and shape of spores also were recorded. Dilutions were performed with the spore masses obtained from fungus fruiting bodies, and drops of suspensions were placed on microscope slides. More than 30 fruiting bodies were sectioned and in total 50 spores derived from different fruiting bodies were selected randomly to measure ...

Cytospora paraplurivora sp. nov. isolated from orchards with fruit tree decline syndrome in Ontario, Canada

“…was among the causative agents of canker and dieback diseases in fruit trees including Prunus spp. [ 4 , 5 ]. Generally, members of the Cytospora spp.…”