Some Factors Influencing Lipid Storage in Sclerotia of Sclerotinia Minor

Abstract

In the course of a comparative anatomical and histochemical study of sclerotia and stromata in the Sclerotiniaceae, we observed, using Sudan Black B, small lipid deposits in the cytoplasm of cortical and medullary cells in sclerotia of Sclerotinia minor Jagger. Bullock et al. (1980), using the same stain, found no evidence of lipid deposits in sclerotia of the same species. We were disturbed by this anomaly, both because our other staining results for this species agreed well with those reported by Bullock et al. and because we had used good quality stain with convincing removal of the reactive material in our lipid extraction control. There were two possible explanations. First, we were working with a different isolate of S. minor and there may be variation in lipid storage among isolates. Second, we grew and maintained our isolates on a different nutrient medium, potato dextrose agar (PDA), while Bullock et al. used Czapek-Dox. There is evidence that the quantity of lipid stored in sclerotia may vary with different growth media. Weete et al. (1970) reported differences in the quantities of unsaturated free fatty acids extracted from sclerotia of S. sclerotiorum grown on PDA, syn