Conserved expression pattern of some gene clusters during fruiting body formation among three different basidiomycetous species. Comparative transcriptome analysis of early sexual development in S. commune 4-39/4-40, C. cinerea AB and L. bicolor S238N-H82 was performed. Orthologous genes (best PSI-BLAST hits with E-values ≤ 0.005) to only 446 and 378 up- and down-regulated loci in S1P, respectively, were found in S. commune 4-39/4-40 and L. bicolor S238N-H82. (A) Fruiting body transcriptome data were retrieved in the form of log2 ratios for these loci from the raw data sets and analyzed by centroid-linkage hierarchical clustering. The red sidelines mark the presence of 6 loci clusters which are consistently up (1–4)- or down (5 and 6)-regulated in young fruiting bodies (YFB) and stage 1 primordia (S1P) of the three species compared. (B) Close-up view of the up- and down-regulated clusters highlighted by red bars in (A). Orthologous genes in C. cinerea, S. commune and L. bicolor corresponding to the numbered clusters, as well as the functional annotation of these loci and the cluster-associated Pearson correlation coefficients can be found in Table 5.