Biochemical and Structural Changes in Mitochondria and Other Cellular Components of Pea Cotyledons During Germination

Solomos, T.; Malhotra, S. S.; Prasad, Sheo Mohan; Malhotra, S. K.; Spencer, Margaret Beale

doi:10.1139/o72-101

Cited by 55 publications

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“…The senescence of cotyledons has also been studied (2,14,17,20,23 were soaked in tap water for 6 h. Following this, damaged and nonimbibed seeds were discarded. The remaining seeds were planted in horticultural grade Vermiculite and were germinated at 27 C in the dark for various periods.…”

Section: Introductionmentioning

confidence: 99%

“…The electron microscopy studies of Bain and Mercer (2) and of Solomos et al (20) have shown that there is deterioration in mitochondrial structure at later stages ofgermination. However, Solomos et al (20) isolated active mitochondria 14 days after the onset of imbibition, and Young et al (23) after 10 days. Also, Bain and Mercer (3) found that the young seedling was dependent on the cotyledons, even after the morphological characteristics of the young plant suggested otherwise.…”

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confidence: 99%

“…Experiments done by Young et al (23) showed that if cotyledons were excised from the axis prior to 2 days of development, functional mitochondria failed to develop. Other work done to determine the relationship between the axis and cotyledons in germination has shown that there is an interdependence between the two, with regard to the development of several enzymic activities (3).The senescence of cotyledons has also been studied (2,14,17,20,23 were soaked in tap water for 6 h. Following this, damaged and nonimbibed seeds were discarded. The remaining seeds were planted in horticultural grade Vermiculite and were germinated at 27 C in the dark for various periods.…”

mentioning

confidence: 99%

“…It is now known that following imbibition, there is a rapid increase in several enzymic activities, as well as improvement in mitochondrial structure (2, 15,20). There is no appreciable synthesis of new mitochondria but rather promitochondria, existing in the dry seeds, develop structurally and functionally.…”

mentioning

confidence: 99%

“…The senescence of cotyledons has also been studied (2,14,17,20,23). The electron microscopy studies of Bain and Mercer (2) and of Solomos et al (20) have shown that there is deterioration in mitochondrial structure at later stages ofgermination.…”

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Cyanide-insensitive Respiration in Pea Cotyledons

James¹,

Spencer²

1979

Plant Physiol.

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Mitochondria isolated by a zonal procedure from the cotyledons of germinating peas possessed a cyanide-resistant respiration. This respiration was virtually absent in mitochondria isolated during the first 24 hours of germination but thereafter increased gradually until the 6th or 7th day of seedling development. At this time between 15 and 20% of the succinate oxidation was not inhibited by cyanide. The activity of the cyanide-resistant respiration was also determined in the absence of cyanide. Relationships among mitochondrial structure, cyanide-resistant respiration, and seedling development are discussed.The development of respiratory activity in the cotyledons of germinating peas has been studied extensively by several authors (2, 12, 14-17, 20, 23). It is now known that following imbibition, there is a rapid increase in several enzymic activities, as well as improvement in mitochondrial structure (2,15,20). There is no appreciable synthesis of new mitochondria but rather promitochondria, existing in the dry seeds, develop structurally and functionally.The development of respiratory activity in the cotyledons has been shown to be dependent on the presence of the developing axis (23). Experiments done by Young et al. (23) showed that if cotyledons were excised from the axis prior to 2 days of development, functional mitochondria failed to develop. Other work done to determine the relationship between the axis and cotyledons in germination has shown that there is an interdependence between the two, with regard to the development of several enzymic activities (3).The senescence of cotyledons has also been studied (2,14,17,20,23 were soaked in tap water for 6 h. Following this, damaged and nonimbibed seeds were discarded. The remaining seeds were planted in horticultural grade Vermiculite and were germinated at 27 C in the dark for various periods. Harvesting was done at 24-h intervals following the onset of imbibition.Isolation of Mitochondria. The isolation procedure was basically that of Hamman and Spencer (7). Washed cotyledons (about 250 g) were ground with a mortar and pestle for 8 min in 300 ml of ice-cold extraction medium of the following composition: 0.5 M mannitol, 5 mM EDTA, 0.5% BSA, 0.05% cysteine, and 0.050 M Tes, with pH adjusted to 7.4 at 20 C with Tris. The brei was filtered through one layer of Miracloth and the filtrate was then centrifuged at 700g for 7 min. The supernatant layer was edgeloaded into a Ti-XIV zonal rotor spinning at 1,500 rpm at 2 C in a Beckman Spinco L2-65B centrifuge. Then a sucrose-step gradient was loaded into the rotor. The gradient consisted of 100 ml each of 33, 37.5, and 43% (w/w) sucrose, and sufficient 48% (w/ w) sucrose to fill the rotor. The gradient also contained 0.1% (w/ w) BSA and 1% (w/w) Tes, with pH adjusted to 7.4 at 20 C with Tris. Centrifugation was for I h at 37,000 rpm. Following centrifugation, the rotor was center-unloaded by use of a 50% (w/w) sucrose solution. Protein peaks were monitored with a Pharmacia UV Duo Monitor (model 200). The p...

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Section: Introductionmentioning

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

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Cyanide-insensitive Respiration in Pea Cotyledons

James¹,

Spencer²

1979

Plant Physiol.

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Pea mitochondrial lipids and their oxidation during mitochondria swelling

Haydar

Hadziyev

1974

J Sci Food Agric

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The composition and oxidation of lipids in pea mitochondria induced by swelling in presence of some transitional metal ions and ascorbic acid has been studied.Among the major mitochondrial lipids found were phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and diphosphatidylglycerol. The major fatty acids present in these lipids were linoleic, oleic and palmitic acids. The average unsaturation for mitochondria total fatty acids, expressed as Double Bond Index was 1.44, while the unsaturation for fatty acids of individual lipids varied between 1.02 and 1.73 being highest for an unidentified phospholipid and 1.44 for phosphatidylcholine present in mitochondria as the major lipid.Mitochondria isolated from pea seeds germinated for 4 days were found to be tightly coupled and to have an ADP/O ratio of 1.3. The swelling assay in 0.1 M-KCl for 1-day-old mitochondria has shown a swelling ability matching those of 4 and up to 8 days of age. Isolated mitochondria aged for 24 h at 2-4" C showed a swelling comparable to that of the fresh preparation. Swelling in the presence of ascorbic acid did not induce mitochondrial lipid oxidation. However, this was brought about in the presence of Cu2+ ions. The presence of Fez+ ions induced the highest degree of oxidation, and instead of a concurrent swelling, it induced contraction. At the same level of ions, Fez+ was more effective than Fe3+. Contrary to iron used at 4% of its physiological level, Mn2+ and Co2+ used at 12 to 24% of their levels found in pea seeds were ineffective in inducing oxidation. Nevertheless, the degree of mitochondrial swelling was highest in the medium containing KCl, lower in the presence of Co2+ and ascorbic acid and lowest in the presence of Fe3+. These results suggested that mitochondrial lipid oxidation does not depend on the degree of swelling.The lipid peroxides formed within mitochondria, up to 8 mg of mitochondrial protein, could not be detected by dropping mercury electrode polarography but were readily determined colorimetrically using thiobarbituric acid reagent.

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Respiration Measurements in Plant Roots Throughout Development

Johnson‐Flanagan¹

1989

Modern Methods of Plant Analysis

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Biochemical and Structural Changes in Mitochondria and Other Cellular Components of Pea Cotyledons During Germination

Cited by 55 publications

References 0 publications

Cyanide-insensitive Respiration in Pea Cotyledons

Cyanide-insensitive Respiration in Pea Cotyledons

Pea mitochondrial lipids and their oxidation during mitochondria swelling

Respiration Measurements in Plant Roots Throughout Development

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