The cell death phenomenon during <i>Tuber</i> ectomycorrhiza morphogenesis

<div><p>Cell death phenomenon was investigated during the formation and establishment of <i>Tuber</i> ectomycorrhiza (ECM) with host trees, both <i>in vitro</i> and in pot culture using terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling (TUNEL) reaction, Transmission electron microscopy (TEM) and Enzyme-linked immuno sorbent assay (ELISA). <i>Tuber borchii</i> mycelium and plantlets of <i>Tilia plathyphyllos</i> were used for <i>in vitro</i> ECM synthesis, whereas <i>T. melanosporum</i>, <i>T. aestivum</i> and <i>T. borchii</i> spores and seedlings of <i>Corylus avellana</i>, <i>Quercus pubescens</i> and <i>T. plathyphyllos</i> were employed in pot cultures. Non-mycorrhizal roots showed TUNEL-positive nuclei at the level of cap cells and tracheary elements as a result of physiological root morphogenesis. In contrast, during the pre-symbiotic phase and the following ECM developmental stages, progressive accumulation of tannin/polyphenol deposits developed in epidermal and cortical cells, leading to the cell death but without TUNEL positivity. After this necrosis, a further unexpected autophagic cell death was observed in apparently healthy mycorrhizae, first affecting mycoclena and then the Hartig net hyphae. This series of cell death phenomena involving both root cells and fungal ectomycorrhizal hyphae points to the existence of a genetic orchestration between the two symbiotic partners during ECM morphogenesis and deserves further investigation to elucidate the underlying molecular mechanisms and signaling pathways.</p></div

The challenge for identifying the fungi living inside mushrooms: the case of truffle inhabiting mycelia

<p>The <i>Tuber</i> ascomata (truffles) are a microhabitat for bacteria, viruses, and fungi (yeasts and filamentous fungi). In this survey, we tried to develop a method that would make it possible to define the mycobiome of the truffle-inhabiting filamentous fungi using culture independent molecular methods. The nested quantitative Real-Time PCR allowed us to demonstrate that each truffle is home to multiple species of filamentous fungi and that their DNA is present within the healthy ascoma at the ratio of 10⁻⁶ compared to that of the truffle. Probably due to their insignificant presence, Denaturing Gradient Gel Electrophoresis of the amplification of ITS amplicons showed only those of the host. Based on the results, the possibilities of being able to detect the fungicolous fungi present in very small amounts within a fungal host are discussed.</p