Overexpression of Chinese flowering cabbage BpPMSR3 enhances the tolerance of Arabidopsis thaliana to cadmium

Soil pollution by the heavy metal cadmium (Cd) is a global environmental problem that adversely affects plants and humans. For example, Cd easily contaminates Chinese flowering cabbage (Brassica rapa parachinensis). To investigate the molecular mechanism of Cd tolerance in Chinese flowering cabbage, we cloned a Cd tolerance-related gene named BpPMSR3 in this study. The full-length cDNA of BpPMSR3 is 555 bp with an open reading frame encoding 184 amino acids. Phylogenetic analysis indicated that BpPMSR3 was closely related to Brassica rapa PMSR in different species. Functional analysis showed that the root lengths and fresh weights of transgenic Arabidopsis thaliana plants overexpressing BpPMSR3 decreased a lower ratio than Col-0 under 50 mu M Cd condition, compared to plants grown under -Cd condition. However, Cd absorption did not differ between Col-0 and transgenic lines. The methionine (Met), glutathione (GSH), and phytochelatin concentrations in transgenic lines were higher than those in Col-0, whereas the methionine sulfoxide (MetSO) concentration in transgenic lines was lower than that in the wild type Col-0. These results reveal that the tolerance of transgenic Arabidopsis plants to Cd was higher than that of Col-0. The transcription levels of AtHMA3, AtMAN3, and AtNramp1, which were related to Cd tolerance, were significantly higher in transgenic lines than in Col-0 in the presence of Cd. Therefore, Chinese flowering cabbage BpPMSR3 improved the tolerance of transgenic Arabidopsis plants to Cd.