Thiol redox state and oxidative stress affect sclerotial differentiation of the phytopathogenic fungi Sclerotium rolfsii and Sclerotinia sclerotiorum.
OBJECTIVE
To investigate the involvement of oxidative stress and thiol redox state (TRS) in sclerotial differentiation of Sclerotium rolfsii and Sclerotinia sclerotiorum.


RESULTS
Oxidative stress in these fungi was assessed by lipid peroxidation, which was higher in comparison with their nonsclerotiogenic counterpart strains. TRS [measured as glutathione (GSH) and cysteine] was associated with oxidative stress and differentiation using the TRS modulator and antioxidant Nu-acetylcysteine (AcCSH) and the GSH biosynthesis inducer and inhibitor l-2-oxo-thiazolidine-4-carboxylate and L-buthionine-S,R-sulphoximine (BSO) respectively. Differentiation and oxidative stress was decreased by AcCSH in both fungi. The decrease of differentiation by BSO was not associated with oxidative stress in these fungi.


CONCLUSIONS
Differentiation and oxidative stress in both fungi depends on the availability of antioxidant noncytotoxic -SH groups and is not depended on any direct antioxidant role of GSH and its precursor cysteine.


CONCLUSIONS
This study helps to understand the mechanism(s) of sclerotial differentiation in these agriculturally important phytopathogenic fungi and proposes that AcCSH can be used as potent fungicide by (i) acting as growth inhibiting cytotoxic oxidant and (ii) sustaining these fungi in their undifferentiated hyphal stage where they are vulnerable to degradation by soil micro-organisms.
Patsoukis
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Department of Biology, Section of Genetics, Cell Biology and Development, University of Patras, Patras, Greece.
Georgiou
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D000111:Acetylcysteine / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001203:Ascomycota / Q000254:growth & development / Q000378:metabolism*; D001487:Basidiomycota / Q000254:growth & development / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D025301:Hyphae / Q000166:cytology / Q000378:metabolism; D015227:Lipid Peroxidation; D009172:Mycology; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010935:Plant Diseases / Q000382:microbiology*; D013438:Sulfhydryl Compounds / Q000378:metabolism*
D000975:Antioxidants; D005656:Fungal Proteins; D013438:Sulfhydryl Compounds; D000111:Acetylcysteine