First report of root rot caused by Ceratobasidium sp. AG-Fa on Capsicum annuum in Pakistan
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First report of root rot caused by Ceratobasidium sp. AG-Fa on Capsicum annuum in Pakistan Aliya Tariq 1,2 & Farah Naz 1 & Muhammad Shahid 1 & Amjad Shahzad Gondle 1 & Abdul Sattar 1 & Muhammad Nabeel 1 & Zobia Jabeen 1 & Imran Hassan 3 Received: 20 August 2019 / Accepted: 4 July 2020 # Società Italiana di Patologia Vegetale (S.I.Pa.V.) 2020
Keywords AG-Fa . Capsicum annuum L. . Islamabad . Rhizoctonia-like fungi
In November 2017 and 2018, bell pepper (Capsicum annuum L.) seedlings showed symptoms of root rot in three greenhouses located at Islamabad, Pakistan, with 17–28% mean disease incidence. The symptoms comprised water-soaked lesions on the crown and roots. The lesions later turned brown, quickly girdle the tender and young stem with the formation of canker. Infected seedlings wilted and roots rotted with the progression of disease. Small sections of diseased tissues were surface disinfected with 1% sodium hypochlorite for 2 min, rinsed three times in sterile distilled water, and after drying plated on potato dextrose agar (PDA) supplemented with streptomycin sulphate. The Petri plates were incubated at 25 °C for 48 to 72 h. The colonies of twenty isolates were initially cream later turning light to dark brown. The sclerotia were dark brown, developed on aerial hyphae and measured 1.0 to 4.0 × 1.0 to 3.0 mm (average 2.5 × 2.0 mm). The fungus had septate hyphae, binucleate, sub-branching at right angle with slight constriction at the origin of branching of mycelium and septum. The morphological characteristics were consistent with those of Rhizoctonia-like fungi Ceratobasidium sp. (Sneh et al. 1991). The DNA of two representative isolates was extracted (Reader and
* Aliya Tariq [email protected]
Broda 1985) and internal transcribed spacer region (ITS) was amplified using ITS1/ITS4 primers (White et al. 1990). The obtained sequences were deposited in GenBank and accession numbers were obtained for isolate FJR57 (accession no. MN328248) and FJR58 (accession no. MN328249). BLASTn searches of both sequences showed 99.8% identity with Ceratobasidium sp. st rai n AG-Fa iso lat e Y T- 5- 4- 1 (ac ce ss ion N o . KT265715). In pathogenicity tests, each isolate was inoculated on three healthy seedlings of bell pepper with a suspension of 106 conidia/ml by root drenching. As reference controls, three seedlings were inoculated with sterile distilled water. Inoculated and control seedlings were kept in a greenhouse at 25 °C. After two weeks, all inoculated seedlings developed water soaked, light to dark brown lesions, after wilting with the formation of canker. No disease symptoms developed on reference control plants. Ceratobasidium sp. was consistently reisolated from inoculated seedlings and isolates were morphologically similar to the mother cultures. To the best of our knowledge this is the first report of Ceratobasidium sp. causing root rot of bell pepper in Pakistan. Also, bell pepper has not been reported as the host of Ceratobasidium sp. AGFa from any part of the world. Acknowledgements Thi
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