Expression of chitin synthase genes in the arbuscular mycorrhizal fungus Gigaspora margarita

Abstract

Genomic DNA from spores of the endomycorrhizal fungus Gigaspora margarita was amplified with two sets of degenerate primers designed on conserved regions of chitin synthase polypeptides. Three chitin synthase (chs) gene portions were identified : Gimchs1, Gimchs2 and Gimchs3, encoding one class II and two class IV chitin synthases, respectively. Gimchs1 and Gimchs3 transcripts were detected by reverse transcription polymerase chain reaction (RT-PCR) during root colonization, whereas none of three mRNAs was revealed during spore germination. The potential role of the genes expressed is discussed in the light of morphogenetic and signalling events.

Spatial monitoring of gene activity in extraradical and intraradical developmental stages of arbuscular mycorrhizal fungi by direct fluorescent in situ RT-PCR

“…Expression profiling of fungal genes in the AM symbiosis has so far been based on studies of RNA extracted from germinating spores, mycorrhizal roots or extraradical mycelium (Harrison and van Buuren, 1995;Kaldorf et al, 1998;Lanfranco et al, 1999; Fer- rol et al, 2000Requena et al, 2002Requena et al, , 2003Tamasloukht et al, 2003;Breuninger and Requena, 2004;Benedetto et al, 2005;Govindarajulu et al, 2005). However, most of these analyses give only a general picture of overall transcript levels in the targeted fungal tissues.…”

“…Determination of genes or proteins that are implicated in the symbiotic stages of AM fungal development is still difficult because the fungal tissues are imbricated within root tissues. Thus, AM fungal gene expression has so far been studied using in vitro RT-PCR on RNA extracted from germinating spores (Lanfranco et al, 1999), from intraradical (mycorrhizal roots) or extraradical mycelium associated with roots (Harrison and van Buuren, 1995;Kaldorf et al, 1998;Lanfranco et al, 1999;Ferrol et al, 2000;Requena et al, 2003;Benedetto et al, 2005;Govindarajulu et al, 2005). However, gene expression profiling based on tissue extracts does not provide information about spatial distribution at the cellular level, especially in AM where fungal-plant interactions are not uniform within roots, except where specific fungal tissue (arbuscules) has been targeted by microdissection (Balestrini et al, 2007).…”

Molecular–Physiological Aspects of the AM Symbiosis Post Penetration

“…for the production of the chitinious cell wall (Lanfranco et al 1999), for storage lipids and glycogen in the developing spores (Bonfante et al 1994) and for long-lasting proteins like the glomalin which is discussed to be important for soil aggregation (Purin and Rillig 2007). These processes are less well investigated, but nevertheless important for understanding mycorrhizal functioning.…”

Cell wall remodeling in mycorrhizal symbiosis: a way towards biotrophism

“…Several fungal genes encoding enzymes involved in cell wall metabolism are expressed during AM fungal colonization, suggesting a role in the remodeling of the fungal cell wall during intracellular colonization (Lanfranco et al, 1999; Tisserant et al, 2012, 2013). AM fungal cell walls undergo a conspicuous change in their organization during their life cycle: the spore wall is thick and layered with a highly fibrillar chitin, while the hyphal wall becomes progressively thinner during the intracellular phase, reaching a thin amorphous structure in the thinner arbuscular branches (Bonfante et al, 1990b).…”