The Response of Several Enzyme Activities from Arabidopsis thaliana after the Treatment with Mercury

The Response of Several Enzyme Activities from Arabidopsis thaliana after the Treatment with Mercury

Three-week grown Arabidopsis thaliana leaves were wounded by cutting whole leaves with a razor blade into pieces (about 3 mm × 3 mm), submerged in solutions containing various concentrations of mercuric chloride (0, 0.05, 0.1 and 0.2 mM), and incubated in a growth chamber for 24 h at 25°C. We measured and compared activities of various enzymes such as phenylalanine ammonia-lyase, tyrosine ammonia-lyase, thioredoxin, thioltransferase, and glutathione reductase. Treatments leaves with mercury resulted in a dose-dependent decrease in activities in phenylalanine ammonia-lyase, thioredoxin, and thioltransferase. Whereas glutathione reductase activity was drastically decreased at 0.05 mM mercury treatment compared to control, and then was slightly increased at concentrations more than 0.05 mM. Our results strongly indicate that sulfhydryl-related and phenylpropanoid-synthesizing enzyme activities are affected by treatment with mercuric chloride. Further studies, however, remain to elucidate the mechanisms involved.