Molybdenum (Mo) in rhizosphere influences sulfate assimilation as well as a number of other physiological aspects. In this study, the activity of key enzymes in sulfate assimilatory pathways, such as ATP sulfurylase (ATPs), adenosine 5'-phosphosulphate reductase (APR), as well as the responses of reactive oxygen species (ROS), were analyzed to elucidate the metabolic and physiological effects of external Mo supply to detached leaves of Trifolium repens L. Mo supply with a range from 1 mM to 40 mM depressed the activity of ATPs throughout the entire time course. In the leaves exposed to 1 mM Mo, a continuous decrease in the activity of ATPs was confirmed by Native-PAGE. The APR activity was also declined by Mo treatment. The accumulation of H2O2 and O2 were not significant up to 10 mM Mo, whereas a remarked accumulation was detected under 40 mM Mo supply. The data suggest that an external supply of Mo has an inhibitory effect on sulfate assimilation, and induces oxidative stress only at an extremely high concentration.

• Qian Zhang(Department of Animal Science, Institute of Agriculture Science and Technology, College of Agriculture & Life Science, Chonnam National University)
• Bok-Rye Lee(Department of Animal Science, Institute of Agriculture Science and Technology, College of Agriculture & Life Science, Chonnam National University)
• Sang-Hyun Park(Department of Animal Science, Institute of Agriculture Science and Technology, College of Agriculture & Life Science, Chonnam National University)
• Gi-Ok Jeong(Department of Animal Science, Institute of Agriculture Science and Technology, College of Agriculture & Life Science, Chonnam National University)
• Tae-Hwan Kim(Department of Animal Science, Institute of Agriculture Science and Technology, College of Agriculture & Life Science, Chonnam National University) Corresponding author