Ultrastructure of Dormant and Germinated Basidiospores of a Species of Psilocybe

Abstract

SUMMARYThe ultrastructure of dormant and germinated basidiospores of a species of Psilocybe was studied using standard thin sectioning and freeze-etching techniques. The results obtained with freeze-etching generally agreed with those obtained with thin sectioning. Dormant basidiospores possessed a thick wall composed of three layers, each of which differed in electron density from the other two layers. The dormant spores were typically binucleate (the nuclei containing well defined pores) and contained numerous mitochondria, lipid bodies and ribosomes, but endoplasmic reticulum was lacking. The plasma membrane was well defined and contained many invaginations. Germination was rapid, occurring in 2–4 hr, and was induced by treating the spores with a hot water extract of horse dung. Germinated spores developed numerous small vacuoles and germ tubes were more electron dense than the cytoplasm in dormant spores. Otherwise, the dormant and germinated spores were similar in their ultrastructural details. Several aspects of spore germination are discussed.