Rmm. Crawford et al., SIMILARITIES BETWEEN POSTISCHEMIC INJURY TO ANIMAL-TISSUES AND POSTANOXIC INJURY IN PLANTS, Proceedings of the Royal Society of Edinburgh. Section B: Biological sciences, 102, 1994, pp. 325-332
The return to air after periods of oxygen deprivation has long been kn
own to be associated with injury from active radicals in a variety of
animal tissues (post-ischaemic injury or reperfusion injury). In plant
s, a similar sequence of events has been suspected, but only on the ba
sis of indirect evidence of peroxidative damage to membrane lipids. Th
e role of free radicals in causing such injury was investigated in the
rhizomes of two Iris species, one tolerant of anoxia (Iris pseudacoru
s) and one intolerant (Iris germanica). Rhizomes of both species were
subjected to total anoxia for 7 days. In the following post-anoxic per
iod, when normal air supply was restored, the generation of active rad
icals was detected by Electron Paramagnetic Resonance (EPR) only in th
e anoxia-intolerant I. germanica. Radical generation was exclusively i
n the rhizodermis and never observed in the rhizome cortex. The radica
ls were successfully scavenged with the antioxidants ascorbic acid and
reduced glutathione. A direct parallel can therefore be drawn between
post-ischaemic injury in animal tissues and post-anoxic injury in pla
nts on the basis of direct observation of active radical generation in
sensitive tissue. The avoidance of this type of injury is discussed i
n relation to variation in flooding tolerance, anoxia and other stress
es in higher plants.