Membrane Lipid Breakdown in Relation to the Wound-induced and Cyanide-resistant Respiration in Tissue Slices

Abstract

A study of a variety of bulky storage organs and fruits reveals that fresh slices fall into two categories with respect to their sensitivity to CN. Fresh slices in the first class are CN-sensitive, whereas slices of the second class are resistant to, and often stimulated by, CN alous (17). Their CN sensitivity has been attributed to the loss of the alternative path (27) due to extensive membrane lipid destruction initiated by slicing. Furthermore, regeneration of the CNresistant pathway, and the burgeoning of glycolysis and the tricarboxylic acid cycle (12,14) in aged potato slices were viewed as the result of specific membrane biosynthesis (33,34). The question arises whether these physiological transitions are ubiquitous in tissue slices or unique to the potato slice.Here, tissue slices from a variety of bulky storage organs and fruits were examined to determine whether slicing in general initiates a burst of lipolytic activity analogous to that found in potato and how slicing affects CN resistance and the utilization of exogenous glucose. The contribution of the alternative path of the wound and wound-induced respiration was estimated (2,28,29), as well as its magnitude, to establish the extent of its participation. MATERIALS AND METHODS PLANT

Binding of Butyl Gallate to Plant Mitochondria

“…It has long been known that respiration in intact, untreated potato tubers is cyanide-resistant (12). Further, Theologis and Laties (25) concluded that the cyanide-sensitivity of mitochondria isolated from freshly sliced, untreated potato tubers was due to the extensive lipolytic activity that appears upon slicing and not the inherent absence ofthe alternative pathway. How these observations relate to the role played by the engaging factor as outlined in Figure 4 is still unclear.…”

Influence of Growth Temperature on Respiratory Characteristics of Mitochondria from Callus-Forming Potato Tuber Discs

“…Several authors suggested a relationship between the development of a CN-resistant respiration and the mitochondrial membrane lipid composition in aging potato slices (12,17,23). In studies on adaptations of plant cells to low temperatures, it has been reported that the mitochondrial membrane lipid composition changes with temperature, which might serve to maintain membrane fluidity (4,7,9).…”

Wound-Induced Membrane Lipid Breakdown in Potato Tuber

“…A slice 10 mm from the core face resembles the ordinary conventional fresh thin potato slice, i.e., its respiration is (32), as well as to glycolysis (19) and glucose transport (6). Accordingly, inhibition of conventional metabolism (glycolysis and the tricarboxylic acid cycle) in fresh potatoslices has been attributed by us to the generation of FFA on slicing (28). The suppression of phosphorylation by FFA in turn has been ascribed to the inhibition of the mitochondrial ADP/ATP antiport (32).…”

“…The suppression of phosphorylation by FFA in turn has been ascribed to the inhibition of the mitochondrial ADP/ATP antiport (32). Parenthetically, we have proposed (28) that the marked stimulation of fresh slice respiration by uncoupler is due to the release of this inhibition, in analogy to the effect of uncoupler on oligomycin treated mitochondria.…”

“…Our presumption that CN insensitivity is correlated with membrane integrity has been strengthened by the observation that aged slices show neither lipid breakdown nor loss of CN resistance on further cutting, and the correlation between the absence of lipid breakdown and the persistence of CN resistance in fresh slices of a variety of fleshy storage organs is good (28 (28). By contrast, PL biosynthesis is indispensable (30).…”