How Exogenous Cadmium Affects Micronutrients Accumulation and the Related Gene Expression Regulation in Brassica juncea

摘要

Cd accumulation in plants not only affects the plant growth, but also further endangers human healthy by plant-derived food process. Brassica juncea L. has been appreciated as the potential Cd hyperaccumulator plant as it is suitable for bioremediation purposes. The previous studies revealed that B. juncea biomass and metabolism were severely affected by Cd stress. However, the relationship between Cd accumulation and micronutrient accumulation in B. juncea remains unknown. Cd shares chemical similarity to Zn, Fe, and Mn and can thus replace them in the ironic related groups of many proteins in plant cells. In the present study, the micronutrients Mn, Zn, Fe, and Cu contents and Cd contents in B. juncea were detected under gradient Cd treatment condition. The result showed that Zn, Mn and Cu accumulation in roots were significantly affected by Cd stress. The main metal and heavy metal transporter family candidates were then identified according to the phylogenetic analysis of related homologues in Arabidopsis thaliana, B. napus and B. juncea. We further investigated the expression level of BjNramp, BjHMA, BjCET and BjMTPs genes under 1 and 5 μM Cd treatment condition by qRT-PCR assays. The result revealed that BjNramp1;4, BjNramp3;5, BjNramp3;10, BjNramp4;4, BjHMA3, and BjHMA4 might be involved in the uptake of Cd, Cu, Zn and Mn by the roots under low (1 μM) Cd treatment. The present study is important to understand the relation between micronutrient and heavy metal uptake, and provides essential information for the phytoremediation on soil heavy metal contamination to coordinate the detoxification of heavy metal and micronutrient accumulation.