Induced Activity of Superoxide Dismutase and Peroxidase of in vitro Plants by Low Concentrations of Ethanol

Abstract

Plant tissue culture media and bioassay solutions often contain a trace amount of ethanol because ethanol is a common solvent for certain chemicals such as plant growth regulators, antibiotics, or herbicides. The effect of this trace amount of ethanol on enzyme activities in plants is often overlooked. This study investigated whether trace amounts of ethanol alter the activity of certain enzymes. Cucumber seeds were incubated on filter papers with a thin layer of water containing 0-2.5% (v/v) (ca. 0-428 mM) ethanol under sterile conditions. At the 7th day of incubation, morphological scoring and enzymatic measurement of superoxide dismutase (SOD) and peroxidase (POD) were conducted. Seeds did not germinate in 2.5% ethanol, and seedling growth was significantly reduced in 1.25% ethanol. Seed germination and seedling growth were visually normal in 0.25% or less ethanol, but the increase of POD activity in roots of the seedlings germinated in 0.25% ethanol was highly significant compared to the control (without ethanol). The activities of SOD and POD in roots were positively correlated with ethanol concentrations. The results indicate that ethanol can induce SOD and POD activity and that trace amount of ethanol in plant culture media can significantly alter the activity of certain enzymes without noticeable stress on plants. Therefore, one should be alert to the effects of ethanol during experimental design and data interpretation if ethanol is used as a solvent for certain chemicals in cell cultures, or bioassays, for physiological, biochemical, or gene expression analyses.