Meiosis in Coprinus. V. The role of light on basidiocarp initiation, mitosis, and hymenium differentiation in Coprinus lagopus

Abstract

Primordial bud formation in Coprinus lagopus is strictly light dependent, but only [Formula: see text]exposure to light is required. However, continued exposure to light is mandatory for further development and hymenium differentiation into a mature basidiocarp. Without light, the stipe of the primordial bud elongates as if the basidiocarp is maturing and the primordial bud eventually aborts. The optimum light intensity is less than 1 ft-c at a wavelength of 410–450 nm. It is possible that cap and stipe are initiated by the same stimulus, but further development of each is under different controls. The former is light dependent whereas the latter is not.The primordial bud development was studied at daily intervals for 3 days until meiosis started and their structural differentiations were studied by paraffin section and squash preparations. The cap of the primordial bud has three zones: the veil, the hymenium, and the stipe. The veil cells are large and multinucleate and lack clamp connections. The stipe includes a central column of dikaryotic hyphae and a cortex of giant multinucleate cells. The hymenium contains only dikaryotic hyphae, which later develop into basidia, cystidia, and medullar cells. The gill development is started by structural organization of dikaryotic hyphae into dome-shaped ridges, which is followed by disintegration of cells surrounding these ridges to form gills. The gill expansion is also light dependent.When the primordial buds were exposed to light, there was a thrust of mitotic activity. Mitotic metaphase, anaphase, and telophase configurations were clearly demonstrated.