Polymorphic Variation in the Structure of Aerial Sclerotia of Coprinus cinereus

Abstract

Aerial sclerotia of different wild-type strains of Coprinus cinereus differed in their internal structure. The more common of the two polymorphic forms (called the Z-type) had a rind which was only one cell thick; the other form (the H-type) had a rind many cells thick which extended to at least half the diameter of the sclerotium. Visible light microscopy, ultraviolet fluorescence microscopy and scanning electron microscopy were used to characterize the sclerotia formed by a range of dikaryotic mycelia to establish the genetic relationships between the polymorphic structures. The Z-type is the wild-type and genetically dominant form. The H-type is a naturally occurring variant caused by an allele of the gene scl-1 which we designate scl-1 H. The scl-1 H allele is recessive to wild-type but is dominant to the previously known allele of scl-1 (now designated scl-1°). Strains carrying scl-1° fail to produce sclerotia and since its allele scl-1 H causes the formation of sclerotia having an abnormal proliferation of cells, particularly in the rind, it is suggested that the scl-1 gene may normally be involved in the control of the disposition and extent of tissue layers during sclerotium development.