Lipoxygenase-generated hydroperoxides account for the nonphysiological features of ethylene formation from 1-aminocyclopropane-1-carboxylic acid by microsomal membranes of carnations

Lynch, Daniel V.; Sridhara, Sampath; Thompson, John E.

doi:10.1007/bf00391036

Cited by 71 publications

(36 citation statements)

References 14 publications

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“…A second inductive treatment of 24 h continuous illumination at the end of these 5 short days again resulted in the changes mentioned before (Table 3). As expected from literature data (Mayak, Legge, and Thompson, 1981;McRae, Baker, and Thompson, 1982;Lynch, Sridhara, and Thompson, 1985;Kevers and Gaspar, 1985), a microsomal fraction from spinach leaves converted ACC to ethylene in vitro in the presence of manganese (Table 4). Calcium ions up to 10 mol m~3 appeared uneffective (data not shown) but no difference could be seen in the rates of ACC conversion to ethylene by micTosomes between vegetative and induced plants (Table 4).…”

Section: Resultssupporting

confidence: 88%

“…microsomal and cell wall. Activity of the microsomal fraction is in good agreement with studies indicating that ACC conversion to ethylene is associated with membrane systems (Imaseki and Watanabe, 1978;Mayak et al, 1981;McRae et al, 1982;Lynch et al, 1985). As far as we know, conversion of ACC to ethylene by a cell wall fraction has not been reported until now.…”

Section: Discussionsupporting

confidence: 88%

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Ethylene Production in Spinach Leaves during Floral Induction

Crèvecœur¹,

Penel²,

Greppin³

et al. 1986

J Exp Bot

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Crevecoeur, M., Penel, C, Greppin, H. and Gaspar, Th 1986. Ethylene production in spinach leaves during floral induction.-J. exp. Bot. 37: 1218-1224.Spinach plants were induced to flower by transferring them from short days to continuous light. Their leaf laminae released more ethylene than those from vegetative plants. These leaves also exhibited a greater capacity to convert exogenous ACC into ethylene. Cell wall preparations from the leaves of continuously illuminated plants also converted exogenous ACC into ethylene more readily than extracts from short day plants. These effects and also those previously reported for peroxidases appear very similar to these brought about by various environmental stresses such as pollution and mechanical irritation.

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Section: Resultssupporting

confidence: 88%

Section: Discussionsupporting

confidence: 88%

Ethylene Production in Spinach Leaves during Floral Induction

Crèvecœur¹,

Penel²,

Greppin³

et al. 1986

J Exp Bot

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“…This is evident from the finding that there is an increase in the saturated:unsaturated fatty acid ratio of senescing petal membranes (6). Moreover, there is also evidence that the hydrolytic release of free linoleic and linolenic acids from membrane phospholipid results in enhanced lipoxygenase activity and an accumulation of peroxidized lipids in bilayers, leading to further destabilization of membrane structure (33).…”

Section: Discussionmentioning

confidence: 96%

An ethylene-induced cDNA encoding a lipase expressed at the onset of senescence

Hong

Wang

Hudak

et al. 2000

Proc. Natl. Acad. Sci. U.S.A.

101

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M embrane deterioration is an early and characteristic feature of plant senescence engendering increased permeability, loss of ionic gradients, and decreased function of key membrane proteins such as ion pumps (1). One of the clearest manifestations of this is the onset of membrane leakiness measurable as increased conductivity of diffusates from intact tissue. This is detectable in carnation petals, for example, well before petal inrolling, the first morphological manifestation of senescence in this tissue, and also before the climacteric-like rise in ethylene production (2). The decline in membrane structural integrity at the onset of senescence appears to be largely attributable to accelerated metabolism of membrane lipids and ensuing change in the molecular organization of the bilayer. Indeed, loss of membrane phospholipid is one of the best documented indices of membrane lipid metabolism during senescence and has been demonstrated for senescing flower petals, leaves, cotyledons and ripening fruit (3, 4).The selective depletion of phospholipid fatty acids from the membranes of senescing tissues results in an increase in the sterol:fatty acid ratio in the bilayer and a consequent decrease in bulk lipid fluidity. This has been demonstrated by fluorescence depolarization and electron spin resonance for microsomal membranes from senescing cotyledons, flowers, leaves, and ripening fruit (5-8) and for plasmalemma of ripening fruit and senescing flowers (5). The decrease in lipid fluidity is engendered by an enrichment of free sterols relative to fatty acids in the bilayer as fatty acids are cleaved from the membrane lipids and selectively removed, reflecting the fact that free sterols are known to restrict the mobility of phospholipid fatty acids (9). As well, in some senescing tissues, the decrease in bulk lipid fluidity appears to be caused in part by a selective depletion of polyunsaturated fatty acids from membranes and an ensuing increase in the saturated-to-unsaturated fatty acid ratio (6). There are also reports that the large changes in bulk membrane lipid fluidity accompanying senescence may alter the conformation of membrane proteins, rendering them prone to proteolysis (10, 11).Recent data suggest that free fatty acids arising from the metabolism of membrane lipids may be removed from the bilayer by blebbing of lipid particles highly enriched in free fatty acids from the membrane surface into the cytosol (12-14). These lipid particles appear to be structurally analogous to oil bodies. Indeed, there is growing evidence that the free fatty acids released from senescing membranes are metabolized by glyoxylate cycle enzymes also induced at the onset of senescence (15). However, it is also clear that free fatty acids accumulate in senescing membranes and induce lipid-phase separations. The resulting mixture of liquid-crystalline and gel phase lipid domains in the bilayer contributes to the leakiness of senescing membranes because of packing imperfections at the phase boundaries (16).Deesterification of membr...

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“…Lipoxygenase, an enzyme that is capable of forming activated oxygen and initiating lipid peroxidation, is also associated with senescing membranes (16,17). As senescence progresses, linoleic acid and linolenic acid, which are substrates for lipoxygenase, would be among the fatty acids released from membrane phospholipids.…”

mentioning

confidence: 99%

Membrane Deterioration in Senescing Carnation Flowers

Fobel¹,

Lynch²,

Thompson³

1987

Plant Physiol.

109

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The lipid fluidity of microsomal membranes from the petals of cut carnation flowers decreases as the flowers senesce. A comparable chane in fluidity was induced by in vitro aging of microsomal membranes from youn flowers under conditions in which membranous lipoxygenase-like activity was active. There was no change in fluidity when the membranes were aged in the presence of inhibitors of lipoxygenase or were heatdenatured prior to aging. Membranes from naturally senesced flowers and membranes that had been aged in vitro both sustained an increase in saturated.unsaturated fatty acid ratio that accounted for the decrease in lipid fluidity, and in both i s there was evidence for depletion of the unsaturated fatty acids, linoleic acid, and linolenic acid, which are substrates for lipoxygenase. Loss of lipid phosphate reflecdtng breakdown of membrane phospholipids preceded the depletion of unsaturated fatty acids attributable to the lipoxygenase-like activity. The data have been interpreted as indicating that fatty acid substrates for membrane-associated lipoxygenase-like activity are made available by the initiation of phospholipid degrdation, and that the utilization of these substrates results in a selective depletion of unsaturated fatty adds from the membrane and an ensuing decrease in bulk lipid fluidity.Membrane deterioration attributable to lipid degradation and ensuing destabilization ofthe bilayer appears to be a fundamental feature of senescence (28). During the early stages of senescence, there is a pronounced decline in membrane phospholipid that becomes manifested as an increased membrane sterol:fatty acid ratio (2,19,26 lipid fluidity (1,4,19,26). There are also large changes in the phase properties of senescing membranes that have been attributed to lipid peroxidation (24,27).Lipoxygenase, an enzyme that is capable of forming activated oxygen and initiating lipid peroxidation, is also associated with senescing membranes (16, 17). As senescence progresses, linoleic acid and linolenic acid, which are substrates for lipoxygenase, would be among the fatty acids released from membrane phospholipids. In the present study, we have examined the extent to which membrane deterioration in senescing carnation flowers can be attributed to the concerted effects of phospholipid degradation and the action of membrane-associated lipoxygenase-like activity. Epps3 (pH 8.5), and centrifugation at 131,000g for 1 h. The resulting pellet was suspended in 2 mm Epps (pH 8.5), to a concentration of 2 mg protein ml-' and either used directly or dialyzed. In the latter case, 6 ml of membrane suspension (2 mg protein ml-') were dialyzed against 1,000 ml of 10 mm Epps (pH 8.5), at 5°C. The buffer was changed after 1 and 2 h, and dialysis was then continued for an additional 12 h. MATERIALS AND METHODS PlantFor in vitro aging experiments, the membrane suspension was diluted to 0.1 mg protein ml-' in 2 mM Epps adjusted to pH 7.3 or 8.5, and 60 ml of the diluted suspension were incubated in a 50 ml Erlenmeyer flask at 24°C. ...

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Lipoxygenase-generated hydroperoxides account for the nonphysiological features of ethylene formation from 1-aminocyclopropane-1-carboxylic acid by microsomal membranes of carnations

Cited by 71 publications

References 14 publications

Ethylene Production in Spinach Leaves during Floral Induction

Ethylene Production in Spinach Leaves during Floral Induction

An ethylene-induced cDNA encoding a lipase expressed at the onset of senescence

Membrane Deterioration in Senescing Carnation Flowers

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