eCALIBRATOR: A Comparative Tool to Identify Key Genes and Pathways for Defense Against Biotic Stressors.

Many pests and pathogens threaten Eucalyptus plantations. The study of defense responses in this economically important wood and fiber crop enables the discovery of novel pathways and genes, which may be adopted to improve resistance. Various functional genomics experiments have been conducted in Eucalyptus-biotic stress interactions following the availability of the genome, however, comparisons between these studies were limited largely due to a lack of comparative tools. To this end, we developed eCALIBRATOR http://ecalibrator.bi.up.ac.za, a tool for the comparison of Eucalyptus biotic stress interaction. The tool, which is not limited to Eucalyptus, allows the comparison of various datasets, provides a visual output in the form of Venn diagrams and clustering and extraction of lists for gene ontology enrichment analyses. We also demonstrate the usefulness of the tool in revealing pathways and key gene targets to further functionally characterize. We identified 708 differentially expressed genes in common among responses to the insect pest , oomycete pathogen and fungus . Within this set of genes, one of the Gene Ontology terms enriched was "response to organonitrogen compound," with () being a key gene, up-regulated under susceptible interactions and down-regulated under resistant interactions. Although previous functional genetics studies in support a role in nitrate acquisition and remobilization under long-term nitrate starvation, the importance of in plant defense is unclear. The T-DNA mutants of were more resistant to pv. DC3000 inoculation than the wild-type counterpart, supporting a direct role for in plant defense. Future studies will focus on characterizing the ortholog of .