Transcriptome analysis of cadmium-treated Brassica varieties reveals different expression pattern

Cadmium, as a heavy metal, has toxic effects to plant and animals. Some vegetables and oilseed crops might be a cadmium hyperaccumulator while the molecular mechanism behind plant response to cadmium stress is still unclear. In the current study, we sequenced three mRNA libraries from Brassica campestris, B. oleracea, and newtype oilseed rape (B. napus L.) roots responsed to cadmium stress to identify the different express pattern during these varieties. In total, 1,426 differentially expressed genes (DEGs) were found in the Brassica varieties response to cadmium stress. The 109 candidate genes were related to cadmium annotated in Arabidopsis, 67 from newtype oilseed rape, 33 from B. campestris, and 29 from B. oleracea. Various DEGs related to ion transport pathway were enriched in gene ontology (GO) terms. Our results also indicated that metabolism genes related to auxin-affected cadmium accumulation in Brassica roots. Combined with the candidate gene detected by GWAS, several genes were identified and shown to be involved in plant response to cadmium. Our results will provide the basis for the molecular mechanism of Brassica varieties response to cadmium in roots.