SEDL / STP / STP1115-EB / STP19506S

Peroxidase Activity as an Indicator of Sublethal Stress in the Aquatic Plant Hydrilla Verticillata (Royle)

Byl, TD
Memphis State University, Memphis, TN

Klaine, SJ
Memphis State University, Memphis, TN

Pages: 6    Published: Jan 1991

Download this paper for $25 PDF (120K)          View License Agreement
Abstract

This study examines the utility of plant peroxidase (POD) activity as a biochemical indicator of chemical stress in the aquatic plant Hydrilla verticillata (Royle). Plants were raised in 10% Hoagland's solution augmented with 200 mg NaHCO³/L. The plants were exposed to concentrations of exponential increment of Cu²⁺ or the sulfonylurea herbicide, sulfometuron methyl, (methyl 2-[[[[(4,6-dimethyl-2-pyrimidinyl) amino]-carbonyl] amino] sulfonyl] benzoate), also known by the trade name Oust^R. After seven days of exposure the plants were harvested, macerated, and the POD extracted with salt solution. POD was measured by a spectrophotometric assay. There was a significant increase in POD activity after exposure to sublethal concentrations of Cu²⁺ or Oust. This increase in POD activity was dose dependant and concomitant with a decrease in root and shoot elongation. Plants exposed to 1 mg/L Cu²⁺ resulted in a 1.75-fold increase over the controls in shoot POD activity. Plants treated with 1 mg/L Oust resulted in a 1.5-fold increase in shoot POD activity over the controls, yet no necrosis was visible after seven days. These results indicate that measuring the saltextractable POD activity has great potential as a biochemical indicator of sublethal stress in the aquatic plant H. verticillata.