Fig. 2

Differential expression of L. bicolor TFs during the development of poplar (P. trichocarpa) ECM. a Laser-scanning confocal microscopy images of transverse sections of P. trichocarpa roots 2, 4, 6 and 12 weeks after contact with L. bicolor hyphae. Plant root cells are counterstained with propidium iodide and fungal cell walls are revealed using WGA-AlexaFluor 488. Bars indicate 10 μm. b Clustering of 100 differentially expressed L. bicolor TF transcripts (>2.5-fold; BH, modified t-test <0.05) during ECM development (2, 4, 6 and 12 weeks after contact) compared to free-living mycelium (see Additional file 3: Table S3 for the list of transcripts). Log2 transformed data were manually clustered. Each gene is represented by a row of coloured boxes (corresponding to ratio values) and a single column represents each developmental time-point. Regulation levels range from pale to saturated colours (red for induction; blue for repression). White indicates no change in gene expression. Protein IDs are given for each cluster. TFs up- or downregulated during both poplar and Douglas fir ECM development are shown in red and blue, respectively. TFs regulated in an opposite manner in ECM root tips of P. trichocarpa or P. menziesii are in green