The structure and histochemistry of sclerotia of Typhula incarnata

The results of a study of the ultrastracture and histochemistry of sclerotia of the psychrophilic snow mold Typhula incarnata indicated some unique features. These included the following: a continuous, pigmented layer external to the rind of the sclerotium; medullary hyphal walls that contained large amounts of β-1,3 glucans; conspicuous fibrils distributed through medullary hyphal walls; the absence of an extensive extracellular matrix characteristic of sclerotia of many mesophilic fangi; large, usually single, phenol-rich bodies in rind cells; and medullary hyphae that either contained several phenol bodies or protein bodies and polyphosphate granules, some of which were contained within protein bodies. These features are compared with those of sclerotia of mesophilic fungi, and their possible significance is discussed. Key words: sclerotia, sclerotial morphology, sclerotial histochemistry, snow mold, Typhula.