Mycoviruses and their pathogenesis

Submitted to : Dr Yasir Iftikhar

Submitted by : Roll no’s: 24 , 39 , 41, 53

Myco-viruses:

The virus that infect fungi and replicate inside fungi are called Mycovirus.

These are also called as fungal virus ,mycophage and fungicidal virus.

Mycovirus first time was recorded on cultivated mushrooms (Agaricus bisporus) in the late 1940’s and was called the La France disease or watery strip .

La France Disease The La France Disease of mushroom is also known as X disease or watery stripe.Due to this Disease:Reduced yieldSlow mycelial growthWater logging of tissueMalformationMiss shaped mushroom

Mycovirology

Mycovirology is the study of viruses infecting fungi.

General characteristicsThey are isometric particles.

The majority of Mycoviruses have segmented double-stranded RNA (dsRNA) genomes.

Approximately 30% have positive sense, single-stranded RNA (+ssRNA) genome.

Host range

Mycoviruses are found in all four phyla of the true fungi.

Chytridiomycota

Zygomycota

Ascomycota

Basidiomycota

Symptoms associated with Mycoviruses:

Infections with fungal viruses often remain persistently unappear in their hosts.

Micoviruses can alter phenotypes, such as reduced growth, pigmentation, lack of sporulation .

Changes of colony and lesion in morphology of fungus is very important .

Transmission

Natural vectors of Mycoviruses are unknown due to lack of extracellular movement from cell to cell.

Intercellular transmissions only through hyphal fusion and cell division and spread via sexually or asexually spores have been observed .

Vegetative incompatibility reactions inhibit hyphal fusion and reduce viral transmission.

Movement of mycoviruses within fungi:

Virus dissemination in mycelial networks via dolipores and septa , as organelles easily migrate in between adjacent cells.

Virus can move with the cytoplasm and extends into new hyphae.

Pathogenesis

The majority of Mycovirus families do not exclusively infect fungi.

The families which exclusively infect fungi are Reoviridae Hypoviridae totiviridae. Narnaviridae etc.

Hypovirulence: It is advantageous infection of viruses which

decrease the pathogenicity of plant pathogenic fungi .

It is most common in Mycoviruses and use for biological control.

Its most common example are cryphonecteria

parasitica on chestnut blight.

Importance :

Killer isolates secrete proteins that are toxic to sensitive cells of the same or closely related

species . There are potentially interesting application of killer yeast in medicine, food

industry, and in agriculture.

harmful pests such as Botrytis cinerae ,cryphonecteria parasitica , provide significant

information that Mycoviruses can decrease Fungal pathogencity.

So these can be used as biological control against harmful Fungus.

Are Mycovirus a fungicidal??