Mycoviruses are viruses that infect fungi. They were first observed in cultivated mushrooms in the 1940s, causing a disease called La France Disease. Mycovirology is the study of viruses that infect fungi. Most mycoviruses have double-stranded RNA genomes, though some have positive-sense single-stranded RNA. They can infect fungi in all four phyla. While some mycovirus infections are asymptomatic, others can alter fungal phenotypes like reducing growth or sporulation. Transmission occurs through hyphal fusion or spores. Some mycoviruses like those in the families Reoviridae, Hypoviridae, and Totiviridae exclusively infect fungi. Hypovirulence is when a

2. Mycoviruses and their pathogenesis
Submitted to :
Dr Yasir Iftikhar
Submitted by :
Roll no’s: 24 , 39 , 41, 53

3. 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 .

4. La France Disease
The La France Disease of mushroom is also
known as X disease or watery stripe.
Due to this Disease:
Reduced yield
Slow mycelial growth
Water logging of tissue
Malformation
Miss shaped mushroom

6. Mycovirology
Mycovirology is the study of viruses infecting
fungi.

7. General characteristics
They are isometric particles.
The majority of Mycoviruses have segmented
double-stranded RNA (dsRNA) genomes.
 Approximately 30% have positive sense, single-
stranded RNA (+ssRNA) genome.

8. Host range
Mycoviruses are found in all four phyla of the
true fungi.
Chytridiomycota
Zygomycota
Ascomycota
Basidiomycota

10. 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 .

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

14. 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.

17. 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.

18. Pathogenesis
The majority of Mycovirus families do not
exclusively infect fungi.
The families which exclusively infect fungi are
 Reoviridae
 Hypoviridae
 totiviridae.
 Narnaviridae etc.

20. 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.

22. Importance :

24.  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.

26. Are Mycovirus a
fungicidal??