Mycorrhiza‐like interaction between the achlorophyllous gametophyte of Lycopodium clavatum L. and its fungal endophyte studied by light and electron microscopy

Abstract

The mycorrhiza‐like association of mature gametophytes of Lycopodium clavatum and an endophytic fungus was studied by means of light and electron microscopy. Fine aseptate hyphae of the fungus formed very regular dense hyphal coils and numerous small vesicles of different stages in the cortical cells. Extended infections occurred within preformed spaces between the cells of the storage tissue. These spaces probably arose by degeneration of the host cells. Several hyphae grew within them and were partly swollen or irregularly lobed and branched. They were embedded in a heterogeneous material, probably of host origin. Arbuscles were not established during the interaction. All fungal structures degenerated in the older host tissues that remained intact. The fungus contained bacterium‐like organelles. Elliptic interphase spindle‐pole bodies of the fungus were attached to the outer nuclear envelope. The host‐fungus interaction in the gametophyte of L. clavatum cannot be related to any type of mycorrhizal association described to date. It is therefore called the ‘Lycopodioid mycothallus interaction’. Copyright © 1993, Wiley Blackwell. All rights reserved