Expression of Some Metal Transporter ATPases in Brassica rapa Grown under Cadmium Stress

Abstract

Cadmium (Cd) is one of the toxic heavy metals not essential for the growth and development of plants and other organisms. Brassica rapa accumulates several heavy metals in its leaves and is reportedly suitable for phytoremediation. In this study, Cd uptake and accumulation in the leaves of B. rapa exposed to different cadmium levels (0, 5, 10, 20, 50, 100 μM CdSO4) were analyzed, as well as the effect of Cd stress on HMA2 and HMA4 genes expression were investigated. The qRT-PCR results showed that HMA2 and HMA4 play a vital role in cadmium uptake and translocation in B. rapa at low Cd levels (5-20 μM). However, exposure to high Cd levels (50 and 100 μM) significantly reduced the growth and biomass of B. rapa. Furthermore, high levels of Cd inhibit the expression of HMA2 and HMA4 genes in B. rapa. Our data show a multigenetic (co-acting of many transporter gene clusters) response in the signaling pathway associated with Cd accumulation and tolerance mechanism in B. rapa.