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Effect of the antioxidant ascorbic acid on sclerotial differentiation in Rhizoctonia solani
Author(s) -
Georgiou C. D.,
Petropoulou K. P.
Publication year - 2001
Publication title -
plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.928
H-Index - 85
eISSN - 1365-3059
pISSN - 0032-0862
DOI - 10.1046/j.1365-3059.2001.00608.x
Subject(s) - rhizoctonia solani , ascorbic acid , sclerotium , lipid peroxidation , biology , mycelium , antioxidant , oxidative stress , microbiology and biotechnology , biochemistry , botany , horticulture
Rhizoctonia solani produces ascorbic acid at levels dependent on its developmental stage and its ability to differentiate and form sclerotia. It was found that oxidized exceeded reduced ascorbic acid by a maximum of fourfold in the undifferentiated mycelia, and 2·5‐fold in the differentiated mycelia and sclerotia. Ascorbic acid profiles were very distinctive between differentiating and nondifferentiating R. solani isolates. In the nondifferentiating isolate the ratio of reduced : oxidized ascorbic acid was constant throughout growth, while in the differentiating isolate it increased 1·7‐fold and decreased 1·3‐fold in the middle and at the end of sclerotial differentiation, respectively, compared with the undifferentiated stage. The differentiation‐associated marker of oxidative stress – lipid peroxidation – was 2·8‐fold higher in colonies of the differentiating isolate before they differentiated than in same‐day colonies of the same age of the nondifferentiating isolate. In the differentiating isolate, exogenous ascorbic acid up to 8 mg mL −1 caused a dose‐dependent inhibition of up to 100% of fully developed sclerotia and a delay of 3·5 days in formation of sclerotial initials, apparently acting as an antioxidant and lowering lipid peroxidation to levels similar to those in the nondifferentiating isolate. The data from this study support the hypothesis that oxidative stress induces differentiation in sclerotium‐producing plant pathogenic fungi.