ULTRASTRUCTURE OF THE MYCORRHIZA FORMED BY <i>TETRACLINIS ARTICULATA</i> (VAHL) MASTERS (<i>CUPRESSACEAE</i>)

Abstract

The structural organisation of the endomycorrhiza in naturally infected seedlings and micropropagated and Glomus inoculated plants of Tetraclinis articulate was studied by means of light and electron microscopy. Hyphal spread from cell to cell in the host root was entirely intercellular. Intracellular hyphae crossing through the host walls were never observed. This could be favoured by the presence of numerous wall swellings at the contacting area among cell walls which are characteristic of T. articulate roots. These wall swellings could impede the crossing of the hyphae. The reduced interfacial region between both symbionts was observed with a fibrillar material in contact with the hyphal wall and, in some cases, in contact with the host plamalemma, although sometimes this region was occupied by small vesicles. The increase of the cytoplasmic organules both in the host cell and intracellular hyphae, during the arbuscular phase, indicated an increase of the metabolic activity of both symbionts. The membrane formations, generally referred to as plasmalemmasomes, appeared in the arbuscular interfacial zone and in the cytoplasm of the arbuscular hyphae. This is a typical arbuscular mycorrhiza.