Thylakoid membrane stability in drought-tolerant and drought-sensitive plants

Schwab, Karin; Heber, U.

doi:10.1007/bf00951458

Cited by 53 publications

(26 citation statements)

References 27 publications

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“…First, both carnosic acid and carnosol can protect chloroplast membranes against high light-induced oxidation. Because biomembranes are targets of high light, drought, and high temperatures (Schwab and Heber, 1984;Conde et al, 2011), the accumulation of those antioxidants is beneficial in Mediterranean climatic conditions. In rosemary, there is a wide diversity of carnosic acid accumulation levels in leaves (Wellwood and Cole, 2004).…”

Section: Discussionmentioning

confidence: 99%

Carnosic Acid and Carnosol, Two Major Antioxidants of Rosemary, Act through Different Mechanisms

et al. 2017

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Carnosic acid, a phenolic diterpene specific to the Lamiaceae family, is highly abundant in rosemary (Rosmarinus officinalis). Despite numerous industrial and medicinal/pharmaceutical applications of its antioxidative features, this compound in planta and its antioxidant mechanism have received little attention, except a few studies of rosemary plants under natural conditions. In vitro analyses, using high-performance liquid chromatography-ultraviolet and luminescence imaging, revealed that carnosic acid and its major oxidized derivative, carnosol, protect lipids from oxidation. Both compounds preserved linolenic acid and monogalactosyldiacylglycerol from singlet oxygen and from hydroxyl radical. When applied exogenously, they were both able to protect thylakoid membranes prepared from Arabidopsis (Arabidopsis thaliana) leaves against lipid peroxidation. Different levels of carnosic acid and carnosol in two contrasting rosemary varieties correlated with tolerance to lipid peroxidation. Upon reactive oxygen species (ROS) oxidation of lipids, carnosic acid was consumed and oxidized into various derivatives, including into carnosol, while carnosol resisted, suggesting that carnosic acid is a chemical quencher of ROS. The antioxidative function of carnosol relies on another mechanism, occurring directly in the lipid oxidation process. Under oxidative conditions that did not involve ROS generation, carnosol inhibited lipid peroxidation, contrary to carnosic acid. Using spin probes and electron paramagnetic resonance detection, we confirmed that carnosic acid, rather than carnosol, is a ROS quencher. Various oxidized derivatives of carnosic acid were detected in rosemary leaves in low light, indicating chronic oxidation of this compound, and accumulated in plants exposed to stress conditions, in parallel with a loss of carnosic acid, confirming that chemical quenching of ROS by carnosic acid takes place in planta.

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Section: Discussionmentioning

confidence: 99%

Carnosic Acid and Carnosol, Two Major Antioxidants of Rosemary, Act through Different Mechanisms

et al. 2017

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“…They also show that an oligosaccharide, raffinose, can effectively prevent the crystallization of sucrose. Sucrose has been shown to protect isolated thylakoids from desiccation damage in vitro (25). Freeze-dried spinach thylakoids KOSTER AND LEOPOLD retained approximately 50% of their photophosphorylation activity when dried in the presence of sucrose.…”

Section: Resultsmentioning

confidence: 99%

“…Glucose and fructose were also effective, but sorbitol and proline were not. Schwab and Heber (25) have shown that the resurrection plants Craterostigma plantagineum and Ceterach officinarum contain about eight times the amount of soluble sugar as desiccation-intolerant spinach does. In a related paper, Schwab and Gaff (24) demonstrated that two species of desiccation tolerant grass accumulate large amounts of sugar (from 20-35% on a dry weight basis) as they dry.…”

Section: Resultsmentioning

confidence: 99%

Sugars and Desiccation Tolerance in Seeds

Koster

Leopold²

1988

Plant Physiol.

410

307

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Soluble sugars have been shown to protect liposomes and lobster microsomes from desiccation damage, and a protective role has been proposed for them in several anhydrous systems. We have studied the relationship between soluble sugar content and the loss of desiccation tolerance in the axes of germinating soybean (Glycine max L. Merr. cv Williams), pea (Pisum sativum L. cv Alaska), and corn (Zea mays L. cv Merit) axes. The loss of desiccation tolerance during imbibition was monitored by following the ability of seeds to germinate after desiccation following various periods of preimbibition and by following the rates of electrolyte leakage from dried, then rehydrated axes. Finally, we analyzed the soluble sugar contents of the axes throughout the transition from desiccation tolerance to intolerance. These analyses show that sucrose and larger oligosaccharides were consistently present during the tolerant stage, and that desiccation tolerance disappeared as the oligosaccharides were lost. The results support the idea that sucrose may serve as the principal agent of desiccation tolerance in these seeds, with the larger oligosaccharides serving to keep the sucrose from crystallizing.Most angiosperm seeds can survive desiccation but only at a discrete developmental stage. If they are dried before reaching the desiccation tolerant stage of maturity, they will not germinate (2,26). Similarly, if they are dried after germination has progressed too far, they will not continue to germinate upon rehydration (4,18,26). The emergence of the radicle from the seed coat is generally considered to be the stage at which desiccation tolerance is lost during germination (26).Water is important to organisms not only as a solvent for biochemical reactions, but as a stabilizer of structure. Hydrophilic and hydrophobic interactions impart structure to macromolecules and organelles within cells. Membrane structure, in particular, depends on these complex interactions, and is often regarded as a primary site of desiccation damage (6, 26). The water replacement hypothesis suggests that polyhydroxy compounds can substitute for water in stabilizing membrane structure in the dry state (7,23,30 Leakage of Electrolytes. Seeds were imbibed for periods up to and beyond radicle emergence, then transferred to a chamber containing saturated LiCl, which equilibrates to 11% RH (21). Here the seeds dried to approximately 8% moisture content (dry weight basis). This low moisture content is lethal to desiccationintolerant tissues. After drying, the seeds were transferred to 100% relative humidity for 24 h for slow rehydration in order to minimize damage to cells from hydrational forces (15). Thus, leakage from cells damaged by desiccation should be the main source of the electrolytes measured. Groups of 10 axes were isolated and submerged in 15 mL of deionized water. Conductivity was monitored continuously with an ElectroMark Conductivity Meter (Markson Science, Inc., Del Mar, CA). The rate of leakage was measured after 15 min, by which time it ...

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“…Under such conditions, CO 2 cycling between photorespiratory CO 2 release and photosynthetic CO 2 fIxation allows the maintenance of a considerable light-driven electron transport which protects the photosynthetic machinery from photoinhibition. Chlorophyll a fluorescence analysis has shown that the relation between dehydration and loss of photosynthetic activity is similar between drought-tolerant and drought-sensitive species (Schwab and Heber 1984). In fact, in the absence of hardening during a period of slow dehydration, even leaves of most higher resurrection plants and poikilohydric lower plants lose their photosynthetic activity irreversibly.…”

Section: Plant Metabolismmentioning

confidence: 99%