Hierarchical clustering of micro-array results. Hierarchical clustering of 236 transcripts from P. sylvestris expressed in the roots in response to the presence of the ectomycorrhizal fungus L. bicolor. Each row illustrates the expression profile of each of the significantly expressed genes (identified by mixed model analysis). Light red to deep red indicates increasing levels of expression and light blue to deep blue represents decreasing levels of expression). These ESTs have been divided into 8 regulatory patterns, as indicated by the numbers 1–8.