Hierarchical clustering analysis of differentially expressed genes from 16 libraries of pigeonpea using HCE version 2.0 beta web tool. Clusters of genes highly expressed in different libraries of pigeonpea genotypes subjected to FW and SMD stress. Columns represent different cDNA libraries and their relationship in a dendrogram. Clustering of highly expressed ESTs (normalized using R statistics, R>8) into four major clusters (indicated in vertical colour bars), and their cluster sub groups based on their library specificity. Colour scale represents the range of expression pattern by different genes with respect to libraries.