Effects of Moderately Enhanced Levels of Ozone on the Acyl Lipid Composition of Leaves of Garden Pea (Pisum Sativum) (original) (raw)
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Lipid Content in the Primary Leaf of Bean (Phaseolus vulgaris) After Ozone Fumigation
Zeitschrift für Pflanzenphysiologie, 1981
Phospholipid composition was monitored in the primary leaves of 15-day-old pinto bean plants (Phaseolus vulgaris L.) (age of maximum sensitivity) after exposure to ozone. At threshold doses, which produce spotting and flecking over 15-20 % of leaf surface area (0.3/1111 for 1 h), no significant losses of total lipid phosphate or individual fatty acids occurred for up to 24 h. No change in phospholipid composition (based upon mole percent) was noted for up to 5 h after treatment. After 5 h, there is relatively less PG and more PE in ozone-treated leaves. The molar ratio of galactolipids remained unchanged throughout the 24-h period. Exposure of leaves to 0.5 /1111 ozone, which induces necrotic regions covering greater than 50 % of the leaf surface area, caused no initial change in phospholipid composition. After 3-5 h, however, loss in PG and gain in PE exceeded the changes produced by the lower ozone doses. There is a significant decrease in the MGDG/DGDG molar ratio by 24 h. Thus, exposure of bean leaves to ozone causes only small alterations in PE and PG lipids, alterations which occur several hours after exposure. Such lipid changes are consistent with the loss of general cellular function, but are not the initial result of ozone exposure.
Effects of ozone on the plasma membrane proteins in Arabidopsis thaliana (L.) leaves
Plant, Cell and Environment, 1997
The protein pattern of leaf plasma membranes from Arabidopsis thaliana (L.) Landsberg erecta was analysed in order to detect changes induced by acute short-term ozone treatment. Plasma membranes were isolated 0, 3 and 8 h after the end of a 2 h fumigation of the plants with 500 nmol mol -1 of O 3 . Proteins extracted from plasma membranes were separated by high-performance twodimensional polyacrylamide gel electrophoresis. Eight hours after the end of fumigation, one new protein appeared and the amounts of two other proteins increased significantly. The reported study is a first step towards the identification of plasmalemma proteins altered by ozone and to a more detailed characterization of structural changes occurring in the plasma membrane after ozone exposure.
Ca2+ Transport in Membrane Vesicles from Pinto Bean Leaves and Its Alteration after Ozone Exposure
PLANT PHYSIOLOGY, 1990
The influence of ozone on Ca2+ transport in plant membranes from pinto bean (Phaseolus vulgaris L. var Pinto) leaves was investigated in vitro by means of a filtration method using purified vesicles. Two transport mechanisms located at the plasma membrane are involved in a response to ozone: (a) passive Ca2+ influx into the cell and (b) active Ca2+ efflux driven by an ATP-dependent system, which has two components: a primary Ca2+ transport directly linked to ATP which is partially activated by calmodulin and a H / Ca2+ antiport coupled to activity of a H+-ATPase. The passive Ca2+ permeability is increased by ozone. A triangular pulse of ozone stimulates a higher influx of Ca2+ than does a square wave, even though the total dose was the same (0.6 microliter per liter x hour). Leaves exposed to a square wave did not exhibit visible injury and were still able to recover from oxidant stress by activation of calmodulin-dependent Ca2+ extrusion mechanisms. On the other hand, leaves exposed to a triangular wave of ozone, exhibit visible injury and lost the ability of extruding Ca2+ out of the cell.
Plants (Basel, Switzerland), 2017
The interactive effects of drought and ozone on the physiology and leaf membrane lipid content, composition and metabolism of cowpea (Vigna unguiculata (L.) Walp.) were investigated in two cultivars (EPACE-1 and IT83-D) grown under controlled conditions. The drought treatment (three-week water deprivation) did not cause leaf injury but restricted growth through stomatal closure. In contrast, the short-term ozone treatment (130 ppb 12 h daily during 14 day) had a limited impact at the whole-plant level but caused leaf injury, hydrogen peroxide accumulation and galactolipid degradation. These effects were stronger in the IT83-D cultivar, which also showed specific ozone responses such as a higher digalactosyl-diacylglycerol (DGDG):monogalactosyldiacylglycerol (MGDG) ratio and the coordinated up-regulation of DGDG synthase (VuDGD2) and ω-3 fatty acid desaturase 8 (VuFAD8) genes, suggesting that membrane remodeling occurred under ozone stress in the sensitive cultivar. When stresses wer...
OXIDATION STRESS INDUCE LEAF LIPID CHANGES
The results of studies devoted to lipid involvement in adaptation processes show that just galactolipids monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) are among the most susceptible polar lipids. MGDG and DGDG occur in all higher plants and are the predominant lipid components of chloroplast membranes. The third glycolipid is sulfolipid sulfoquinovosyl diacylglycerol (SQDG) with a sulfonic acid derivative of glucose. They are thought to be of major importance to chloroplast morphology and physiology, although direct experimental evidence is still lacking. . The glycerolipid DGDG is exclusively associated with photosynthetic membranes and thus may play a role in the proper assembly and maintenance of the photosynthetic apparatus . Bearing in mind that oxidative stress is a component part of the reaction of plants to many other stresses, any changes in lipid composition are of special significance. Data available evidence that oxidative processes induced by high concentration of ozone affect glycolipid composition. observed marked decreases in these galactolipids, which started within 2 hours of the onset of ozone exposure. Loss of MGDG was more rapid than that of DGDG, resulting in a significant reduction of MGDG/DGDG ratio in spinach and snapbean ) at least. T.Sakaki considers the first phase of the injury development to continue for the initial 8 h of exposure. A little loss of pigments and lipids (MGDG significantly and DGDG slightly) accompanied by slight increase of MDA content take place while this period. However, marked oxidation of ascorbate and inactivation superoxidismutase (SOD) and ascorbate peroxidase (AP) have already occurred during this period. The second phase characterised by massive destruction of pigments and lipids starts with drastic fall of MGDG and less sharp decrease of DGDG accompanied by significant increase of TG, 1,2-DG and MDA . But it is interesting that anionic lipid -SQDG and PI -amounts were stable while the time of exposure (in spinach leaves, at least). Lipid changes similar to those in spinach were also observed in several plant species, and in broad bean leaves the SQDG increase took place. Oxidative stress induced fall of both GL (MGDG especially drastic) content while SQDG l evel was stable in a number of plants. As a result SQDG content relative to glycolipid quantity increased by 7-45% (depending upon species) . But results obtained by with garden pea evidence that moderately enhanced ozone level caused large decreases not only in the contents of MGDG and DGDG, but in SQDG also. Compared with charcoalfiltered air, fumigation with ozone resulted in decreased 18:3 and increased 18:2 in MGDG and SQDG, while the fatty acid composition of DGDG was unaffected. Concerning the molecular bases of these structural changes suggested that the primary reaction of ozone is the stimulation of galactolipase activity resulting in the enhanced production of free fatty acid in chloroplasts. It is considered that an increase in galactolipase activity is a general feature in response to ozone. demonstrated that ozone stimulated degradation of galactolipids in garden pea leaves probably by galactolipase without effects on the de nova lipid synthesis. Besides, it is well-known that galactolipids as unsaturated compounds are good substrate for forming peroxidation products observed at ozone action . Therefore it seems to be worthwhile to explore various tension
Effects of in vitro treatment with ozone on the physical and chemical properties of membranes
Physiologia Plantarum, 1981
Treatment of microsomal membranes from cotyledons of Phaseolus vulgaris with ozone raises the liquid-crystalline to g,el lipid phase transition temperature and results in the formation of distinct domains of gel phase lipid in the membranes. Liposomes prepared from the total lipid extracts of ozone-treated membranes undergo phase separations just a few degrees below the transition temperature for intact membranes, indicating that the fonnation of gel phase lipids is largely attributable to ozone-induced alterations in the membrane lipids. Levels of unsaturated fatty ,acids as well as the sterol to phospholipid ratio are markedly reduced in the ozone-treated membranes, and the neutral lipid fraction from treated membranes shows an increased propensity to induce the formation of gel phase phospholipid when incorporated into liposomes of egg phosphatidylcholine. Since gel phase phospholipid also forms in naturally senescing plant membranes and appears to be attributable to changes in the neutral lipid fraction, the effects of natural senescence and ozone on membranes have been compared.
New Phytologist, 1995
Spring wheat {Triticum aestivum L, cv, Drabant) was exposed to different concentrations of ozone in open-top chambers in a Held of commercially grown wheat. The following treatments were used: charcoal-Hltered air (CF), non-filtered air (iNF) and non-filtered air supplemented with 25 nl 1"^ ozone (NF-f) and 35 nl 1"' ozone {NF-f-+) for 7hd"'. Flag leaves were analysed for chlorophyll content, total fatty acid composition and fatty acid compositions and contents of monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), phosphatidylcholine (PC) and phosphatidylethanolamine (PE), I'he chlorophyll content decreased significantly with time and ozone concentration. After 4 wk of exposure, the content of MGDG was significantly lower in flag leaves from the NF+ + treatments than in those from the other treatments. The contents of DGDG and PC also decreased while that of PE increased, although these changes were not statistically significant. In the total lipid extract the proportion of 18:3 decreased with time and ozone concentration. Similar changes occurred in MGDG 18:3 at a later stage. Using the concept of accumulated exposure over threshold (AOT), it was evident that the parameters studied differed in ozone sensitivity. After 4 wk of exposure, the best linear dose-response relationships between accumulated exposure and chlorophyll as weli as MGDG contents were obtained with a threshold ozone concentration of 30 n! 1"V For total lipid 18:3 and MGDG 18:3 the corresponding thresholds were 40 and 50 nl 1"\ respectively. Furthermore, the sensitivity to ozone, expressed as loss of chlorophyll, increased with increasing fiag leaf age. In leaves exposed for 7, 13 and 20 d, the best linear fits were obtained with AOT50, AOT40 and AOT30, respectively. In conclusion, ozone sensitivity increased with Hag leaf age and different membrane constituents were differently sensitive to ozone. The results support previous suggestions that ozone causes premature senescence m wheat Bag leaves.
Plant Science, 2007
Levels of acyl-hydrolase (EC 3.1.1.26) activity toward monogalactosyldiacylglycerol (MGDG) varied greatly not only in leaves of 12 plant species but also in those of 11 cultivars of kidney bean (Phaseolus vulgaris L.). The activity was detected in soluble and particulate fractions from kidney bean leaves, and the specific activity in both fractions was higher in young premature leaves than in the old in Koshu Shakugosun, a cultivar exhibiting the highest specific activity among kidney bean plants tested. The enzyme was purified 868-fold with a yield of 8.2% from the particulate fractions of leaf homogenate of this cultivar. The purified enzyme showed a single band on native polyacrylamide gel electrophoresis and a native molecular mass of 74 kDa. The enzyme had broad substrate specificity toward classes of glycolipids, phospholipids, and monoacylglycerol, but was inactive to triacylglycerol, indicating that the enzyme belongs to non-specific lipid acyl-hydrolases. Distinct from other lipid acyl-hydrolases previously reported, however, the enzyme showed preferential hydrolysis at sn-1 position of MGDG. Antiserum prepared against the purified enzyme completely inhibited not only the purified enzyme activity but also the activity in the soluble fraction of leaf homogenate. Exposure to ozone, a stress to stimulate endogenous acyl hydrolysis of MGDG, of kidney bean cultivars with different acyl-hydrolase activity resulted in essentially the same changes in leaf lipids of all cultivars.