Superoxide Dismutase as an Anaerobic Polypeptide

Abstract

The perennating organ, the rhizome, was chosen for examination of response to anoxia in the species Iris pseudacorus L., Iris germanica L. var Quechei, and Glyceria maxima (Hartm.) Holmberg. These monocots are known to differ in their tolerance of anoxia. Intact rhizomes were subjected to periods of prolonged anoxia of up to 28 days and superoxide dismutase (SOD) activity was determined in a 48 hour postanoxic recovery phase. Tests were performed to ensure the accuracy of the measured enzyme activities. In the most anoxia tolerant species, I. pseadaorus, SOD activity rose continuously during the period of imposed anoxia, and levels were maintained in the postanoxic recovery phases: 28 days brought about a 13-fold increase to 1576 U SOD per milligram protein. Small increases were found in the less anoxia tolerant I. germanica during anoxic/postanoxic phases, while a drop in activity was recorded in the least anoxia tolerant G. maxima. However, initial levels in G. maxima were more than twice as high as in the other two species. Experiments applying cycloheximide to anoxic rhizome slices of I. pseudacorus inhibited the increase in SOD activity. This indicates that SOD is, paradoxically, induced under anoxia and we suggest that in this species SOD is one of the enzymes identified as anaerobic polypeptides. The significance of the induction ofan 'oxygen-protecting' enzyme during complete oxygen deprivation is discussed with regard to a possible critical role duning recovery from anoxic stress.

Biochemical Performance of Rice (Oryza sativa) Genotypes under Submergence Stress in Odisha, India

“…The tolerant genotype had higher root activity, hence could transport more O 2 through the shoot to the roots under complete submergence (Sarkar&Bera1997). The present study is in consonance with the findings of Monk et al, (1987). According to Puckridge et al, (2008) the activities of these enzymes were higher only in the tolerant genotypes in comparison to susceptible genotypes which support the present study.…”

The Submergence Tolerance Regulator SUB1A Mediates Crosstalk between Submergence and Drought Tolerance in Rice

“…In addition to dehydration tolerance, the ability to manage ROS detoxification can influence survival of a submergence event. The specific activity of SOD is more significantly induced upon reoxygenation in rhizomes of submergence-tolerant Iris pseudacorus than intolerant Iris germanica (Monk et al, 1987), which is negatively correlated with lipid peroxidation (Blokhina et al, 1999). Similarly, submergence-tolerant FR13A rice, the donor of SUB1A in this study, restricts lipid peroxidation and chlorophyll degradation following desubmergence compared with intolerant IR42 (Ella et al, 2003).…”

Expression of antioxidant defense genes in mung bean (Vigna radiata L.) roots under water-logging is associated with hypoxia tolerance

“…Monk et al (1987) were one of the first workers to report a continuous increase in SOD activity in rhizomes of Iris pseudocorus under water-logging stress. The results obtained from this study suggest that the increase in antioxidative enzymes during water-logging may also be to scavenge the build up of oxidative stress during waterlogging.…”