Volume 17 Part 1 Article 2: The Enigma of Double-Stranded RNA (dsRNA) Associated with Mushroom Virus X (MVX)

Volume 17 Part 1 Article 2
Year 2008
Title: The Enigma of Double-Stranded RNA (dsRNA) Associated with Mushroom Virus X (MVX)
Authors: J.R. Rao, H.S. Shekhar Sharma, D.W.A. Nelson and S. McClean


The emergence of an unusual Agaricus bisporus mushroom ‘patch disease’ first reported in 1996 in the UK, and later termed as ‘mushroom virus X’ (MVX), exhibits a wide range of symptoms (e.g. barren patches beside healthy looking mushrooms, arrested pins, premature opening, browning, off-colour and distortions in shape). This devastating disease is now more widespread and prevalent in a number of European countries (e.g. Netherlands, Ireland) with variations in symptoms and ranging in occasional to severe outbreaks leading to crop losses. Findings from various laboratories in the UK, the Netherlands and Ireland indicate that symptomatic MVX mushrooms contain a variable compendium of novel 26 (dsRNA) elements, ranging in size between 20.2 kb and 0.64 kb, including some (~17/26) in non-encapsidated form. These (a) may comprise multiple viruses, (b) have four low molecular weight dsRNA bands (sizes 2.0–0.6 kb) that are consistently synchronous to mushroom off-colour/browning symptoms, and (c) their hybridisation patterns suggest that they may constitute a single viral type not necessarily the causal agent of the symptom, but due to an unknown stress. Other dsRNA bands and their partial sequences would suggest a range of novel or incognisant viruses or hypoviral elements, but they seem to lack clear relationships with the specific symptoms. Low levels of ‘homologous’ mushroom viruses such as ssRNA virus mushroom bacilliform viruses (MBV) were also detected in A. bisporus spawned compost and diseased fruiting bodies.

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