RP9 Terrestrial Ecotoxicology
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(HAM-1117-846640) Comparative Analysis of the Toxic Effects of Perchlorate in Arabidopsis and in Sorghum.

Hamissou, Mijitaba¹, Dunkerley, Ray¹, ¹ Jacksonville State University, Jacksonville, Alabama, USA

ABSTRACT- Perchlorate contamination in ground water was recently reported in several southwestern states of the United States. It is used in rocket fuel, airbags, matches, and ammunition. When released into the environment, perchlorate becomes an environmental pollutant posing potential immunotoxic conditions in plants and animals. Environmental contaminants alter plant growth and metabolism. However, some plant species have evolved to tolerate or accumulate soil and water contaminants by extracting them from their immediate surrounding. The toxic actions of perchlorate are believed to be exerted on key metabolic enzymes. Like heavy metal pollutants, perchlorate may induce a burst of reactive oxygen species (ROS) creating therefore conditions for secondary oxidative stress to the plants. Literatures reviewed have indicated that higher plants respond to environmental pollutants by sequestering them in their vacuoles or by synthesizing phytochelatin and small molecular weight proteins to neutralize the toxic effects. In this research, mortality, growth parameters, and the activities of ROS scavenger molecules, superoxide dismutase (SOD) and peroxidase (PO) are investigated in arabidospsi thaliana and sorghum bicolor grown in perchlorate solutions. Plants were screened in potted soil and hydroponically in perchlorate containing solutions, adjusted to pH 6.9 for 14 days. Chlorosis, biomass production, and mortality rate were measured daily for 14 days. SOD and PO activities were determined from the cytoplasmic proteins and isolated chloroplasts at the conclusion of the experiment. The data indicated that perchlorate affect arabidopsis more severely than sorghum. The oxidative responses, as measured by the activities of SOD and PO, were significantly higher in Arabidopsis than in sorghum in perchlorate treated plants.

Key words: Perchlorate, Toxicity, Sorghum, Arabidopsis