L'interface plante—champignon dans les ectomycorhizes de truffes: étude ultrastructurale et microanalyses par perte d'énergie des électrons et par rayons X

Abstract

Summary The confrontation between Tuber uncinatum or Tuber magnatum and Corylus avellana or Quercus robur roots leads to ultrastructural modifications. In root, three simultaneous process show an epidermic cell differentiation: radial cell growth, increase of vacuolar volume and cytoplasmic changes. The root cell evolution precedes the Hartig net formation. The interface established between both partners is characterised by a lot of fungal and root plasmalemmasomas. Contacts between plasmalemma and endoplasmic reticulum are frequent. The matrix that joins walls of both symbiots is composed of three constituents: (i) outer mucilaginous wall of fungus; (ii) granular areas which apparently come from cell wall degradation at the time of Hartig net installation; (iii) a lot of fibrilla that establishes bridges between both partners walls. Hartig net establishment brings about the isolation of cells and stops symplasmic transferts. Microlocalisations of calcium and phosphorus are realized in the different parts...