• cell wall;
  • Gigaspora margarita;
  • laser microdissection;
  • Lotus japonicus;
  • mycorrhizal functioning;
  • nutrient transporters;
  • perifungal membrane


  • • 
    Arbuscular mycorrhizas (AMs) contribute significantly to soil nutrient uptake in plants. As a consequence of the fungal colonization and of the deep reorganization shown by arbusculated cells, important impacts on root transcriptome are expected.
  • • 
    An Affymetrix GeneChip with 50 000 probe-sets and real-time RT-PCR allowed us to detect transcriptional changes triggered in Lotus japonicus by the AM fungus Gigaspora margarita, when arbuscules are at their maximum (28 d postinoculation (dpi)). An early time (4 dpi) was selected to differentiate genes potentially involved in signaling and/or in colonization of outer tissues.
  • • 
    A large number (75 out of 558) of mycorrhiza-induced genes code for proteins involved in protein turnover, membrane dynamics and cell wall synthesis, while many others are involved in transport (47) or transcription (24). Induction of a subset (24 genes) of these was tested and confirmed by qRT-PCR, and transcript location in arbusculated cells was demonstrated for seven genes using laser-dissected cells.
  • • 
    When compared with previously published papers, the transcript profiles indicate the presence of a core set of responsive genes (25) that seem to be conserved irrespective of the symbiotic partner identity.