BMC Genomics 2009, 10:415 http://www.biomedcentral.com/1471-2164/10/415 TFrigeuerveie4w and functional categories of hierarchically clustered genes during Ca-Fusarium incompatible interaction Tree view and functional categories of hierarchically clustered genes during Ca-Fusarium incompatible interac- tion. Tree view represents the expression patterns of genes displaying significant regulation in response to Fusarium infection at 24 hours post pathogen inoculation. Genes were organized using hierarchical clustering and displayed, including Cluster1 that represents the significantly repressed genes and Cluster2 that corresponds to significantly induced genes. Each row repre- sents a single gene and each column corresponds to log2 (ratio) of an experimental sample. Black indicates the median level of expression, red indicates greater expression than the median and green less expression. Pie below each cluster shows the dis- tribution of clustered genes into various functional categories. Detailed information on genes within each cluster can be found in additional file 6. gene FOXY, found to be highly adundant both in suscep- tible and resistant genotypes was consistent with that of microarray data. This gene encodes a transposable ele- ment and its induction during plant-pathogen interaction is of interest for the study of such elements and their involvement in immunity vs. disease. Discussion EST sequencing is likely to make its greatest impact on understudied genomes where full genome sequence projects may not be undertaken in near future. Although as of February, 2009 GenBank contained over 45,71,266 entires for the ESTs from plants, most publicly available ESTs are derived from different organs and developmental stages, while the species-specific EST dataset, let alone the genotype-specific ESTs are negligible. Very recently, the focus has been given towards the SNP and copy number variation as a basis for species specific genomic signatures. A recent study in Arabidopsis has revealed one million SNPs in a total population comprising different ecotypes [91]. Further, 78,373 in rice and 65,83,583 in humans were found to be associated with the coding sequences, Page 12 of 21 (page number not for citation purposes)