Gene expression in mature mycorrhizal stages and early infection events including AM marker genes. A: Visualization of gene expression patterns in AM roots for the seven categories referring to mature mycorrhizal stages and the three categories referring to early infection events, as defined in Figure 3. Overlaps between gene expression in mature mycorrhizal stages and early infection events is not shown in this diagram for reasons of simplicity. Numbers in white boxes represent the total number of genes in an expression category, numbers in grey boxes denote the overlap of this category with the 532 genes identified as “AM core set" due to a significant activation in whole roots by different AM fungi . In total, cellular expression patterns were identified for 293 of all 532 genes from the AM core set. B: Detailed results for 16 AM marker genes, including mean signal intensities in the cell-types investigated, with signal intensities above the MtPt4 expression threshold being marked in blue. Expression differences between the cell-types are indicated as follows: red/dark green: expression difference (logFC≥2.32; p≤0.01) for genes expressed above the MtPt4 threshold in only one of the cell-types compared, orange/green: expression difference (logFC≥2.32; p≤0.01) for genes expressed above the MtPt4 threshold in both cell-types compared. Abbreviations: ARB, cortical cells containing arbuscules; CMR, cortical cells from mycorrhizal roots; EPI, epidermal cells from mycorrhizal roots; APP, appressorial areas; NAP, non-appressorial areas; vas, vascular tissue; ind, induced; equ., equally expressed; logFC, log2 fold-change; p, p-value.