Chilling Injury Induces Lipid Phase Changes in Membranes of Tomato Fruit

Abstract

Wide-angle x-ray diffraction has provided evidence for lipid phase separations in microsomal membranes from chill-injured tomato (Lycopersicon esculentum Mill. cv Caruso) fruit. Maturegreen fruit stored for 20 d at 5'C had not begun to ripen and were essentially free of chilling injury symptoms. Within 4 d of being returned to 25"C, however, the fruit displayed characteristic symptoms of chilling injury, including translucent water-soaked patches, surface pitting, and irregular pigmentation. Membrane damage measured as electrolyte leakage from pericarp discs intensified after the fruit were returned to ambient temperature. Wide-angle x-ray diffraction patterns recorded at 25°C for microsomal membranes isolated from untreated, mature-green fruit indicated that the membrane bilayers were exclusively liquid-crystalline. Diffraction patterns for microsomal membranes from fruit stored for 20 d at 5°C showed only trace amounts of gel phase lipid, but within 4 d of subsequent exposure of the fruit to ambient temperature, there was evidence for a pronounced lateral phase separation of lipids within the membranes that would render them leaky. Inasmuch as the phase separations were detectable at 25'C and became pronounced only subsequent to the chilling episode, they appear to be an indirect rather than direct effect of exposure to low temperature. The diffraction data thus support the notion that the lipid phase changes observed here are not directly induced by low temperature but rather reflect subsequent biochemical changes in the bilayers that may contribute to the development of chilling symptoms.

Antisense Suppression of Deoxyhypusine Synthase in Tomato Delays Fruit Softening and Alters Growth and Development

“…DHS-suppressed fruit also exhibited a delay in the onset of electrolyte leakage associated with fruit senescence. Electrolyte leakage is a well-established trait of senescing tissues and is thought to reflect lipid phase changes attributable to enhanced lipase activity and ensuing leakiness of membrane bilayers (Eze et al, 1986;Sharom et al, 1994). Electrolyte leakage for transgenic fruit at 40 d postbreaker was the same as that for wild-type fruit at 20 d postbreaker, confirming a very significant delay in senescence and spoilage of the transgenic fruit.…”

“…Fruits were peeled at the location of measurement due to the resistance of the skin, and firmness was taken to be the amount of pressure required to puncture the surface of the exposed fruit pulp. Electrolyte leakage of pericarp discs from fruit at selected stages of postharvest development was measured at room temperature over a 3-h period using a conductance meter (model 1056; Amber Science, Eugene, OR) as described previously (Sharom et al, 1994).…”

“…3 and 4A). In addition, the onset of electrolyte leakage, which is thought to reflect senescence-induced lipase activity leading to lipid phase changes and membrane leakiness (Eze et al, 1986;Sharom et al, 1994), was delayed in the TP3 fruit (Fig. 5C).…”

Reactive Oxygen Species (ROS) Scavenging in Hot Air Preconditioning Mediated Alleviation of Chilling Injury in Banana Fruits

“…1; CI symptoms in cold-stored bananas. Chilling injury is thought to result in increased membrane permeability leading to an increase in leakage of cellular constituents (Murata, 1990;Sharom et al, 1994). The rate of ion leakage from excised tissue into an isotonic aqueous solution is a useful measure of the severity of chilling-induced increase in membrane permeability (King & Ludford, 1983).…”

Molecular and biochemical investigation of the mechanisms of acclimation to chilling stress in maize seedlings

“…Thus, there are likely other membrane qualities that contribute to the sensitivity of the membrane to low temperature. Sharom et al (1994) have even contested the idea that low temperature directly causes the phase change and have suggested that it is the result of biochemical events occurring during rewarming. Although it is clear that low temperature affects the function of membranes and membraneassociated proteins and that a phase change is associated with chilling injury, there remains much to be discovered about the mechanism by which low temperature affects membrane function and about the qualities of the membranes that are important for chilling tolerance.…”