Determination of inorganic and organic anions in xylem saps of two contrasting oilseed rape (Brassica juncea L.) varieties: Roles of anions in long-distance transport of cadmium

By optimizing chromatographic conditions of an ion chromatographic system, we identified and measured the major inorganic and organic anions (chloride, nitrate, malate, sulfate, phosphate and citrate) in the xylem saps of two contrasting tolerant oilseed rape (Brassica juncea L.) varieties (the high Cd-accumulating genotype Xikou Huazi and the low Cd-accumulating genotype Liangting Huazi). Cadmium concentrations in xylem saps were determined by graphite furnace atomic absorption spectrometry. By analyzing the relationship between anion and cadmium concentrations, we considered that the relatively low phosphate concentrations in Xikou Huazi xylem saps might relate to the relatively high xylem transport of Cd for this genotype, and malate in oilseed rape xylem saps seemed to participate in the long-distance Cd translocation process. Our work might not only be very useful for understanding the mechanisms of Cd hyperaccumulation for Xikou Huazi, but also very beneficial for future application of Xikou Huazi in phytoremediation.