Comparative Transcriptome Analysis between Different Cultivars of Brassica chinensis L. var. chinensis with Low and High Cadmium (Cd) Accumulation Capacities in Response to Short-Term Cadmium Cd Stresses

Screening breeding and popularizing low-Cd accumulative genotypes are of the most important strategy to reduce Cd pollution in crops. In this study, a high-Cd cultivar (HAJS) and a low-Cd cultivar (LAJK) of Brassica chinensis L. var. chinensis (pakchoi) were treated with Cd (1.4mg/L) for 3 hr and 24 hr, and then transcriptomes of roots were performed using Illumina high-throughput sequencing. Main results of the study are as follows:

  1.High-Cd cultivar showed more Cd-induced responses in transcription regulation comparing to low-Cd cultivar in 3 hr Cd treatment. When the Cd stress extended to 24 hr, more Cd-responsive genes were up-regulated to cope with the adverse impacts of Cd in low-Cd genotype than in high-Cd genotype.

  2.The Cd induced genes of HAJS are mainly involved in cell wall biosynthesis, sulfur assimilation process and subcellular Cd-stress tolerance. In LAJK, however, most genes participated in fundamental biosynthesis process and transcription factors took up a large percentage. 

In summary, gene regulations responding to Cd stress were time- and genotype-dependent at transcriptional level in pakchoi. Further bioinformatic analyses would help to clarify detailed molecular mechanisms about genotype difference in Cd accumulation, which would be significant in exploration of molecular breeding methods for low-Cd cultivars of pakchoi.

Keywords: comparative transcriptome, Brassica chinensis L. var. chinensis, Cd-accumulation, molecular mechanism, food safety.