Catalase Activity and Post-anoxic Injury in Monocotyledonous Species

Three anoxia-intolerant species, Glyceria maxima, Juncus effusus and Iris germanica (var. Quechei), and three anoxia-tolerant species Schoenoplectus lacustris, Acorus calamus and Iris pseudacorus were chosen for investigation. Rhizomes of anoxia-intolerant species show increased catalase activities when returned to air after periods of prolonged anoxia. Levels of catalase remained fairly constant in anoxia-tolerant species under the same conditions. In the anoxia intolerant G. maxima, the post-anoxic increase in catalase activity was reduced by circulating the anaerobic atmosphere. This treatment also reduced the ethanol content of the tissue under incubation, and increased the survival of the rhizomes as seen in their ability to resume growth in the post-anoxic phase. Exposure of anaerobic G. maxima rhizomes to ethanol vapour increased post-anoxic levels of catalase activity and when this produced a 5-fold increase always resulted in death of the rhizomes. Acetaldehyde vapour applied in the same way gave rise to increases in catalase activity followed by rapid death of the rhizomes.
It is suggested that post-anoxic oxidation of anaerobically accumulated ethanol may result in a surge of acetaldehyde production, which could exert a toxic effect on the recovering tissues. The possible role of catalase in an ethanol-oxidation reaction, which is well documented in animals, is discussed in the light of the association between the natural accumulation of large concentrations of ethanol and subsequent post-anoxic death in some plant tissues.