Transcriptomic response of multiple Brassica species to Sclerotinia sclerotiorum infection
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To investigate the interplay between polyploid gene expression and biotic stress response, Brassica napus, Brassica oleracea, Brassica rapa, and a synthetic Brassica napus (formed directly from the aforementioned parental species of B. napus) were subjected to the economically devastating fungus Sclerotinia sclerotiorum. RNA-Seq analysis of these pathosystems revealed wide-spread transcriptomic changes involving both constitutive gene expression and alternative splicing. Cross-species comparisons showed a concerted response between all assayed Brassica species characterized by the up-regulation of jasmonic acid signalling pathways, cell-wall defense genes, chitinases, and pathogen responsive genes. Subgenome comparisons also showed considerable non-parental gene expression patterns in the synthetic Brassica napus, in addition to a C-subgenome expression bias, suggesting transcriptome reprogramming occurs relatively quickly following polyploidization.