Oxalic Acid Production by Sclerotinia homoeocarpa: the Causal Agent of Dollar Spot
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Date
2008-06
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The Ohio State University
Abstract
Fungi in the genus Sclerotinia include some of the most devastating plant pathogens known. Oxalic acid is a key pathogenicity factor and its production along with pectolytic cell wall-degrading enzymes by species within this genus is well documented. Dollar spot, caused by S. homoeocarpa, is the most prevalent and sprayed for disease of golf course turf. However, nothing is known about acid production or its role in this species. A series of laboratory-based assays were used to determine whether S. homoeocarpa produces oxalic acid. Potato dextrose agar (PDA) adjusted to pH 4 and pH 6, with and without bromophenol blue (Bb), was used to assess the growth of and acid production by S. homoeocarpa between 5-35 C. When added to PDA, Bb only slightly hindered the growth of S. homoeocarpa. Acid production by S. homoeocapra on PDA + Bb occurred between 15-30 C at both pHs, but was first observed on media adjusted to pH 6. Maximum acid production occurred between 20-30 C. Acid production by S. homoeocarpa was also observed when grown in potato dextrose broth (PDB) at 25 C. High performance liquid chromatography analysis of spent culture broth collected from S. homoeocrapa inoculated PDB revealed the presence of oxalic acid.
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Keywords
Sclerotinia homoeocarpa, oxalic acid, dollar spot, fungus