RT-PCR analysis to detect transcripts of G. intraradices genes in mycorrhizal roots and in arbuscules. Panel A: RNA from whole roots systems of M. truncatula mock-inoculated roots (Mt4) and M. truncatula/G. intraradices mycorrhizal roots (Mt/Gi4). The M. truncatula transgenic plant line pMtSCP1::GFP was used and sampling of colonized root pieces was guided by the expression of GFP. Panel B: RNA from LM cortical cells from M. truncatula mock-inoculated roots (LM-M1, LM-M2 and LM-M3) or cortical cells containing arbuscules from M. truncatula/G. intraradices mycorrhizal roots (LM-Gi3) or M. truncatula/G. versiforme mycorrhizal roots (LM-Gv1 and LM-Gv2). Primers designed to TC105406, a putative G. intraradices α-tubulin a1 gene amplify α-tubulin from both G. intraradices and G. versiforme. This was included as positive control in all samples.G. intraradices glutamine synthetase was included as an additional positive control.