Response to the note to editor: Comments on "transcriptomic response of Arabidopsis thaliana exposed to hydroxylated polychlorinated biphenyls (OH-PCBs)".

In response to Dr. Yang et al.'s comments on our article "Transcriptomic response of Arabidopsis thaliana exposed to hydroxylated polychlorinated biphenyls (OH-PCBs)", additional details were provided regarding the analysis of the gene expression level (One-Way Between-Subject ANOVA) and correction for false discovery rate (FDR) (Benjamini-Hochberg). The gene expression analysis was performed again using the new release of the Transcriptome Analysis Console™ (version 4.0.1, Life Technologies - not available at the time our initial study was conducted), which integrates the Limma differential expression portion of the Bioconductor package. Overall similar results were obtained regarding the number of genes differentially expressed and the enrichment of genes in different Gene Ontology (GO) categories. The transcriptomic profiles induced in response to the three OH-derivatives were shown, again, to be similar to those induced by inhibitors of the brassinosteroid synthesis (i.e., brassinazole, propiconazole, and uniconazole), potentially resulting in iron deficiency in exposed plants. The new (and improved) method used for the selection of differentially expressed genes did not change the conclusion of our initial study, which suggested that the higher phytotoxicity of OH-derivatives, as compared to the parent compound 2,5-dichlorobiphenyl (2,5-DCB), may be explained by the inhibition of the brassinosteroid synthesis pathway.