Variation in copper tolerance in Arabidopsis thaliana accessions Columbia, Landsberg erecta and Wassilewskija

Among the Arabidopsis thaliana accessions Columbia (Col), Landsberg erecta (Ler), and Wassilewskija (Ws), Ler and Ws showed higher copper (Cu) tolerance than Col, while accumulating more Cu. Thus, Cu tolerance did not appear to be related to metal exclusion. Rather, the higher Cu tolerance of Ler and Ws may reflect less Cu-induced nutrient deficiency as they maintained higher sulfur, iron (Fe), and manganese levels than Col under Cu stress. Reverse transcription-polymerase chain reaction was used to compare the leaf transcript levels of nine genes involved in Cu metabolism, oxidative stress resistance or sulfate transport (Sultr 4;1). Excess Cu led to an overall decrease of the transcript levels of plastocyanin and two plastidic Cu transporters, PAA1 and PAA2. The Fe superoxide dismutase (SOD) gene FSD1 was also downregulated in the three accessions, while the cytosolic Cu/Zinc SOD (CSD1) was upregulated compared with the control conditions. These results may be related to differences in Fe and Cu accumulation. The transcript abundance of the Cu chaperones ATX1, CCS and CpCCP showed differential regulation among the three accessions in response to Cu supply. The vacuolar Sultr 4;1 was upregulated by Cu, most likely due to the lower ability to accumulate S. Total non-protein thiol levels were not correlated with Cu tolerance.