Electrophoresis of major proteins in stromata of members of the Sclerotiniaceae

Abstract

Four species in the Sclerotiniaceae were investigated for the presence of major proteins in stromata. Two isolates of Sclerotinia sclerotiorum, 6 isolates of Sclerotinia homoeocarpa, 7 isolates of Sclerotium cepivorum, and 1 isolate of Lambertella subrenispora were grown on complex and defined media. Total protein was extracted from mycelia, sclerotial initials and substratal stromata or sclerotia to determine whether developmental proteins were present. One-dimensional SDS-polyacrylamide gel electrophoresis revealed that all isolates examined produced at least one major protein with a molecular weight of 32–37 kDa. The major proteins comprised up to 45 % of the total protein and were present only in substratal stromata or sclerotia, not in vegetative mycelia. No intraspecific variation was observed in the molecular weight of the major proteins. Protein production was influenced by the medium the isolates were grown on and production of the major protein was enhanced on the complex medium. A protein of lower molecular weight (15–17 kDa) was also produced in lesser quantity (up to 14% of the total protein) by isolates of S. sclerotiorum, S. homoeocarpa and S. cepivorum.