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Regulatory pathways governing modulation of fungal gene expression by a virulence‐attenuating mycovirus.
Author(s) -
Larson T.G.,
Choi G.H.,
Nuss D.L.
Publication year - 1992
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1992.tb05555.x
Subject(s) - biology , library science , virology , computer science
A viral double‐stranded RNA associated with virulence attenuation (hypovirulence) in the chestnut blight fungus (Cryphonectria parasitica) has been shown by DNA‐mediated transformation to be responsible for transmissible hypovirulence. In addition to reduced virulence, the fungal strain harboring this virus exhibits a diverse array of characteristics, termed hypovirulence‐associated traits, which distinguish it from an isogenic virus‐free strain. We have investigated one of these traits, suppressed lac‐1 (laccase) transcript accumulation. Two different and opposing regulatory pathways appear to govern lac‐1 transcript levels in the virus‐free strain: a stimulatory pathway was found to be dependent on the inositol trisphosphate (IP3) and calcium second messenger systems. A second pathway limiting transcript accumulation was shown to require ongoing protein synthesis. Additionally, changes in the level of lac‐1 transcript accumulation were found to be related to modulation of promoter activity and this activity was shown to be suppressed in the virus‐containing strain. We conclude that this hypovirulence‐associated virus interferes with transduction of an IP3‐calcium‐dependent signal that is required for stimulation of lac‐1 transcription. The perturbation of such signal transduction pathways by hypovirulence‐associated viruses may account for the manifold symptoms associated with transmissible hypovirulence.