Heat map representing expression profiles of T. harzianum determined by microarray analysis. A total of 1,220 probe sets showing at least two-fold regulation in response to the presence of tomato plants (MS-P), chitin (MS-Ch) or glucose (MS-G) in the culture medium in comparison to the basal medium alone (MS) were selected for hierarchical clustering. Two biological replicates (1 and 2) from triplicate cultures were used in each experimental condition. Probe sets and samples were ordered using Kendall's tau test and the Ward clustering algorithm through the R software. For each row, the mean expression value in the control condition (MS) was calculated and subtracted from the expression value in the rest of conditions. The red and the green colours represent positive and negative expression changes, respectively, vs. the control condition. The intensity of the colour is proportional to the magnitude of the differential expression. Detailed expression profiles corresponding to the pra 1, pra 2 (former p7480), prb 1 (former p10261), and prb 2 (former p8048) genes are displayed to the right of the figure (results from different probe sets/ESTs representing the same gene are shown independently).