Redox Components in the Plant Plasma Membrane

Abstract

As early as 1945, Lundegardh proposed that redox processes took place in the plasma membrane (PM) of plants. He further envisaged that ion uptake, specifically anion uptake, across the PM of root cells was directly coupled to the flow of electrons to oxygen. This anion respiration was thought to be catalyzed by the respiratory redox components known at that time, mainly the cytochromes. When these around 1950 were discovered to reside in an organelle, the mitochondrion, and not in the PM, the theory of Lundegardh became less tenable (see Lundegardh, 1955) and it gradually lost prominence. However, in hindsight we can now see that his main idea was correct — there is at present plenty of evidence that the PM of both animals and plants contains redox components which can participate in a number of redox processes (see Crane et al., 1985a, b; Luttge and Clarkson, 1985; Moller and Lin, 1986; for comprehensive reviews). In the present review we will critically evaluate the evidence for each redox component proposed to be present in the PM of plants. We will then briefly discuss the possible location of these redox components as well as the various processes they might be involved in.