Role of Sclerin on Morphogenesis in Sclerotinia sclerotiorum de Bary (including S. libertiana Fuckel)

Abstract

A correlation existed between the productivity of sclerin (SCL) and formation of sclerotia or dark pigmentation of old hyphae in Sclerotinia libertiana Fuckel and S. sclerotiorum de Bary. SCL stimulated the activities of phenoloxidase and peroxidase in a mycelial extract of S. libertiana, which appeared to be involved in the maturation and pigmentation of sclerotia. On the other hand, p-aminobenzoic acid (PABA), an inhibitor of phenoloxidase, inhibited the production of both SCL and sclerotia, where assimilation of PABA probably interrupted the biosynthetic process of SCL. When SCL was added at a high concentration, 4×10^-3M, to Czapek's agar medium a strain of S. libertiana which originally formed sclerotia and a strain of S. sclerotiorum which did not form sclerotia but produced melanin-like pigments at the edge of colony formed numerous sclerotium initials, which did not develop normal sclerotia. It was suggested that SCL played a role on induction of sclerotial formation and melanogenesis in these strains, in which a regulation of carbohydrate metabolism was involved.