High efficiency of oxidative phosphorylation in mitochondria of wheat

Sarkissian, Igor V.; Srivastava, H. K.

doi:10.1139/o70-109

Cited by 8 publications

(4 citation statements)

References 3 publications

(3 reference statements)

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“…This is substantiated by the higher ADP: 0 ratios obtained with a-ketoglutarate as substrate. Other studies on mitochondria from wheat (22), mung beans (9), and tomato fruit (10) have indicated that results, both similar and in contrast to those obtained in this study, can be obtained using the same substrates. It is felt, therefore, that the results reported in this paper support the view that mitochondria from various plant sources prepared by different isolation techniques may oxidize the various Krebs cycle substrates at different rates (25).…”

Section: Discussionsupporting

confidence: 86%

“…The possible effect of microbial contamination on respiratory activity was tested by isolating mitochondria in the presence of tetracyclin, a potent inhibitor of microbial respiration, and by isolating mitochondria under standard conditions and then inactivating the mitochondrial respiratory system by incubation at 37 C for 10 min (22). Oxygen uptake is completely abolished by incubation at 37 C but is unaffected by isolation in the presence of tetracyclin, indicating that microbial respiration does not contribute significantly to the observed respiratory rates.…”

Section: Resultsmentioning

confidence: 99%

“…The studies of Sarkissian and Srivastava (20,22) have demonstrated that excellent respiratory control indices and ADP:O ratios greater than the "theoretical" discussed by Lehninger (13) can be obtained from mitochondria of wheat seedlings. They have reported further (25) that respiratory control and ADP:O ratios decline with decreasing age of seedlings, and that these parameters are significantly greater in mitochondria from shoots than from roots or leaves.…”

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confidence: 94%

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Studies on the Respiratory Properties of Mitochondria Isolated from Developing Winter Wheat Seedlings

Pomeroy¹

1974

Plant Physiol.

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The studies of Sarkissian and Srivastava (20,22) have demonstrated that excellent respiratory control indices and ADP:O ratios greater than the "theoretical" discussed by Lehninger (13) can be obtained from mitochondria of wheat seedlings. They have reported further (25) that respiratory control and ADP:O ratios decline with decreasing age of seedlings, and that these parameters are significantly greater in mitochondria from shoots than from roots or leaves. These investigations have demonstrated that the shoots of young wheat seedlings provide an excellent system for the examination of the respiratory properties of plant mitochondria.Current studies (18,23,24) in our laboratory are focused on structural and biochemical changes associated with the development of cold hardiness in plants. Developing winter wheat seedlings attain a high degree of freezing tolerance when grown at 2 to 4 C (4, 17), and this resistance has been correlated with changes in cell membrane composition during growth at low temperature (3, 4). It was decided, therefore, to use the developing winter wheat seedling system to examine both functional responses of isolated wheat mitochondria and structural changes in mitochondrial membranes to growth at low temperature. This paper describes the respiratory properties of mitochondria isolated from developing winter wheat seedlings grown in light and dark at 21 C, from which the system for subsequent low temperature studies was adapted. MATERIALS AND METHODSSeedlings of winter wheat (Triticum aestivum L. cv. Rideau) were germinated and grown at 21 C on moist filter paper in dark and in light (8000 lux) for 2, 3, 5, and 7 days. Two to five g of shoots were harvested in a cold room at 2 to 3 C using precooled glassware and media, and all subsequent operations were carried out at this temperature, unless otherwise noted. The shoots were homogenized for 10 to 20 sec in a mortar and pestle, with grinding medium delivered at a uniform rate from a burette by a fine tube. When the first grinding was completed, the mortar contained approximately 8 ml of grinding medium/g of tissue. The homogenate was filtered through two layers of nylon cloth (mesh about 50 ,um) into centrifuge tubes. The residue in the nylon mesh was transferred to the mortar and pestle, reground with grinding medium, and refiltered through the nylon. Several grinding media were tested (9,19,20), and the most satisfactory was that of Sarkissian and Srivastava (20), composed of 0.5 M sucrose, 1 mM EDTA, 67 mM KH,PO,, and 0.75% (w/v) bovine serum albumin at pH 7.2.Several centrifugation procedures were used initially to isolate mitochondria, including the rapid isolation procedure of Sarkissian and Srivastava (20,21) and the more conventional procedures of Ikuma and Bonner (9) and Raison and Lyons (19). The procedure finally adopted for this study was a modification of the above methods. After filtering through nylon, the homogenate was centrifuged at 2,000g for 5 min, and the resulting supernatant fraction was centrifuged at 20,000g for 4...

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Section: Discussionsupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 94%

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Studies on the Respiratory Properties of Mitochondria Isolated from Developing Winter Wheat Seedlings

Pomeroy¹

1974

Plant Physiol.

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“…However, the activities of both enzymes were considerably lower than those previously reported for wheat mitochondria (26).…”

Section: Methodscontrasting

confidence: 80%

The Effect of Nucleotides and Inhibitors on Respiration in Isolated Wheat Mitochondria

Mk¹

1975

Plant Physiol.

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The effect of mono-, di-, and trinucleoside phosphates and respiratory inhibitors on respiration in winter wheat (Triticumn aestivuim L. cv. Rideau) mitochondria has been examined. When added during state 4 respiration, subsequent to addition of ADP, all of the dinucleotides stimulated oxidation and induced respiratory control with all substrates examined. Similar results were obtained with AMP, but other mononucleotides and all trinucleotides did not affect the rate of oxidation. Nucleoside diphosphates did not stimulate respiration when added prior to the addition of ADP, but subsequent addition of AMP, ADP, or ATP re-established coupled respiration in the presence of the dinucleotides.The duration of 2, 4-dinitrophenol stimulated respiration during oxidation of a-ketoglutarate was found to be dependent on the amount of AMP, ADP, or ATP added, either prior, or subsequent to, addition of the uncoupler. The addition of oligomycin during 2,4-dinitrophenol stimulated respiration reestablished coupled respiration with low ADP/O ratios, when added after addition of ATP or conditions which allow formation of ATP from added ADP. The nucleoside diphosphates, other than ADP, did not stimulate oxidation of a-ketoglutarate in the presence of 2,4-dinitrophenol until a small amount of adenine nucleotide was added to the system. The results suggest that dinucleotides other than ADP, are able to participate in the energy conversion processs of the mitochondria, probably via transphosphorvlation reactions.Studies on the respiratory properties of mitochondria isolated from different plant sources and by different isolation procedures have indicated that considerable variation may exist in their response to various substrates in the presence of uncouplers and respiratory inhibitors (3,16,27,32). Therefore, it is often difficult to extrapolate results obtained from one system to another. The question of which nucleotides are able to act as phosphate acceptors has been examined in several systems from both plant and animal sources (14,21,24 (14), but the role of other nucleotides in phosphorylation reactions in plants is not clear.The present study was undertaken in an attempt to characterize the effect of nucleotides and respiratory inhibitors on respiration in the winter wheat mitochondrial system currently being used in this laboratory to examine structural and functional changes in mitochondrial membranes in relation to growth at low temperature (20). MATERIALS AND METHODSIsolation of Mitochondria. Seedlings of winter wheat (Triticum aestivurn L. cv. Rideau) were germinated and grown in the dark at 24 C on moist filter paper for 2 days. Mitochondria were isolated from the shoots by differential centrifugation (22) and where indicated, further purified by sucrose density gradient centrifugation. Sucrose gradients were prepared by layering 3.7 ml each of 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, and 2 M sucrose solutions containing 10 mm KCl, 10 mm tris-HCl 10 mM KH2PO4, and 0.75% (w/v) BSA at pH 7.2 in 30-ml centrifuge tubes and st...

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An evaluation of mitochondrial heterosis and in vitro mitochondrial complementation in wheat, barley and maize

Sen

1981

Theoret. Appl. Genetics

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Two families each of wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and maize (Zea mays L.) were studied for mitochondrial heterosis and in vitro mitochondrial complementation. Inbred parents and their hybrids were compared for seedling heights and rate of oxygen uptake by the whole tissue to find out if the hybrids showed greater growth and respiratory activity at the seedling stage. Further comparisons were made by isolating mitochondria from the seedling tissues and measuring their ADP∶0 ratio, respiratory control ratio and cytochrome c oxidase activity for mitochondrial heterosis. Mixtures of parental mitochondria were similarly compared with parental and hybrid mitochondria for in vitro mitochondrial complementation. No evidence for mitochondrial heterosis or in vitro mitochondrial complementation was found, nor any correlation between the different mitochondrial parameters, seedling heights or rates of oxygen uptake by seedling tissue. The suggested use of mitochondrial heterosis and in vitro mitochondrial complementation for plant breeding is discussed.

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High efficiency of oxidative phosphorylation in mitochondria of wheat

Cited by 8 publications

References 3 publications

Studies on the Respiratory Properties of Mitochondria Isolated from Developing Winter Wheat Seedlings

Studies on the Respiratory Properties of Mitochondria Isolated from Developing Winter Wheat Seedlings

The Effect of Nucleotides and Inhibitors on Respiration in Isolated Wheat Mitochondria

An evaluation of mitochondrial heterosis and in vitro mitochondrial complementation in wheat, barley and maize

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