Phaeoacremonium species associated with canker and dieback of guava (Psidium guajava L.) trees in Iran
Paper ID : 1910-24IPPC (R2)
Authors
1Department of Plant Protection, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
2Department of Plant Protection, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran.
3Department of Plant Protection, Faculty of Agriculture, Shahid Bahonar University of Kermam, Kerman, Iran
Abstract
Guava (Psidium guajava L) is an evergreen shrub or small tree in the Myrtaceae family. It is an important fruit crop worldwide and in southern Iran. Phaeoacremonium (Togniniaceae, Togniniales) species are ecologically important fungal pathogens and responsible for trunk diseases of forest and fruit trees worldwide. During the spring and summer of 2021, field surveys for fungi associated with trunk diseases in guava trees were conducted in Sistan & Baluchestan province. Branch and trunk samples were collected from trees showing yellowing, dieback and canker symptoms and taken to the laboratory for fungal isolations. The bark of samples was removed, and small wood sections (1 to 3 mm thick) were cut from necrotic wood areas, surface-disinfested for 1 min in a 1.5% sodium hypochlorite solution and washed twice with sterile distilled water. Wood segments were plated onto potato-dextrose-agar (PDA) Petri dishes and incubated at 25°C. The isolates were studied using morphological features, including colony characters and pigment production on malt extract-agar (MEA), PDA and oatmeal-agar (OA) and microscopic structures such as conidiophores, phialides and conidia. Morphological identifications of the isolates were confirmed by sequence analysis of partial β-tubulin gene sequences amplified using primers T1 and Bt2b. In our study, 20 Phaeoacremonium isolates were obtained from necrotic wood tissues of guava trees. Based on their micromorphology, culture characters and β-tubulin gene sequences data, isolates were identified as Phaeoacremonium parasiticum (11 isolates from Chabahar and Konarak) and P. venezuelense (nine isolates from Chabahar). Our study is the first report of P. venezuelense on guava trees in the world. Phaeoacremonium parasiticum was reported previously from guava trees in South Africa and therefore in this study, it is reported for the first time on guava trees in Iran and outside South Africa.
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