Identification of a development-specific protein in sclerotia of Sclerotinia sclerotiorum

Sclerotia of Sclerotinia sclerotiorum contained a major protein of about 36,000 daltons which was not detected in vegetative cells. The protein accumulated rapidly during sclerotial formation and ultimately comprised about 35-40% of the mature sclerotial protein. The protein did not decrease in concentration in sclerotial residue or appear in vegetative cells when sclerotia germinated myceliogenically. In contrast, the concentration of the protein decreased in sclerotia undergoing carpogenic germination and a small amount of the protein was present in the resultant apothecia. This development-specific protein was purified to near homogeneity as judged by one-dimensional polyacrylamide gel analysis. However, at least two other minor protein bands were detected by two-dimensional gel analysis which may be modified forms of the major protein. The protein had an isoelectric point of 6.0 and contained all 20 amino acids commonly present in proteins.