Water Deficits and Enzymatic Activity

Todd, Glenn W.

doi:10.1016/b978-0-12-424153-4.50011-4

Cited by 27 publications

(17 citation statements)

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“…Loss of membrane integrity FIGS. [1][2][3][4] (on preceding page). Ch, chloroplast; i3f, mitochondrion; P, peroxisome; R, ribosomes; Srnb, single membrane bodies (inside the chloroplasts); S, starch; Ph, phosphatase induced lead deposits.…”

Section: Resultsmentioning

confidence: 99%

Some Ultrastructural and Enzymatic Effects of Water Stress in Cotton ( Gossypium hirsutum L.) Leaves

Silva

Naylor

Kramer

1974

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

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Water stress induced by floating discs cut from cotton leaves (Gossypium hirsutum L. cultivar Stoneville) on a polyethylene glycol solution (water potential, -10 bars) was associated with marked alteration of ultrastructural organization of both chloroplasts and mitochondria. Ultrastructural Water stress in some drought intolerant seed plants is accompanied by increased activity of several hydrolytic enzymes [see tabulation by Todd (1) and (2-7)], by change in their intracellular compartmentation (3), and even by loss of part of the protein making machinery (8, 9). One of the hydrolytic enzymes affected, acid phosphatase, appears to be concentrated in the chloroplast. Water stress is accompanied not only by increased acid phosphatase activity (5, 6) but also by release of this enzyme from the organelle. Chloroplasts from drought intolerant cotton plants have been shown to release not only ribonucleic acid into the cytoplasm but ribosomes as well (10). In contrast, drought resistant cotton species have a relatively stable compartmentation of their enzymes including acid phosphatase (6); this is perhaps clue to membrane stability in these taxa.The effects of water stress on photosynthesis (3, 11-13) appear to be duplicatable by the action of lipase (14-16), addition of certain unsaturated fatty acids (17-20), and by aging as shown in isolated plastids (14,17,18,21). Empirically, the addition of inorganic phosphate inhibits CO2 uptake and changes the CO2 compensation point (22). In vivo, a rise in phosphatase activity could lead to an accumulation of inorganic phosphate. Photorespiration is decreased by desiccation. This particular stress effect could be due to a reduction in the production of glycolate. Enhanced lipase activity could also lead to reduced glycine decarboxylation. This speculation is supported by the finding that inhibition of the decar- MATERIALS AND METHODSCotton plants (Gossypium hirsutum L. cultivar Stoneville) were grown in the greenhouse under natural light during the summer of 1972 and in the Duke University unit of the Southeastern Plant Environmental Laboratories. The third leaf from the top of the main axis was sampled at 9 p.m. when the plants were 2 months old. While avoiding main veins, discs of 1.2 cm in diameter were cut from the leaves. The discs were floated, abaxial surface up, for 20 hr on a polyethylene glycol 1540 solution adjusted to -10 bars at 200 under dim light (800 lux). The relative advantages of using polyethylene glycol over mannitol have been discussed by Mfichel (24) and Lawlor (25). Controls were cut from the same tissue and floated in a similar way on distilled water.After the stress treatment, 0.5 X 8-mm strips were sliced from the discs (avoiding the border) and fixed in 4.2% glutaraldehyde in 0. (c) A stressed control was run using the same conditions but without any cytochemical tests.

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Section: Resultsmentioning

confidence: 99%

Some Ultrastructural and Enzymatic Effects of Water Stress in Cotton ( Gossypium hirsutum L.) Leaves

Silva

Naylor

Kramer

1974

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

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“…The double labeling ratio technique coupled with gel electrophoresis was used to study the qualitative effects of water stress on protein synthesis patterns. Details of both of these techniques are presented in an accompanying paper (7 19:1 mixture of N2-air. After the 1.5-hr preincubation, the pressure was released, the radioactive leucine was added to the solution and the pressure was quickly reimposed.…”

Section: Methodsmentioning

confidence: 99%

“…Protein synthesis is one of the biochemical processes that are affected by water stress in plants (12,19 Seattle, Washinigtoni 98195 hydrostatic pressure in the stress-induced changes in protein synthesis, we have compared the effects of water stress, ABA, and hydrostatic pressure on the rate and pattern of protein synthesis in Avena coleoptiles. We will show here that each agent exerts its own distinct effects on protein synthesis.…”

Section: Introductionmentioning

confidence: 99%

“…An imposed hydrostatic pressure alters the pattern of synthesis in stressed tissues, but does not restore the pattern to that found in turgid tissues. Because of the differences in response, we conclude that water stress does not affect protein synthesis via abscisic acid or reduced hydrostatic pressure.Protein synthesis is one of the biochemical processes that are affected by water stress in plants (12,19 Seattle, Washinigtoni 98195 hydrostatic pressure in the stress-induced changes in protein synthesis, we have compared the effects of water stress, ABA, and hydrostatic pressure on the rate and pattern of protein synthesis in Avena coleoptiles. We will show here that each agent exerts its own distinct effects on protein synthesis.…”

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confidence: 99%

“…Protein synthesis is one of the biochemical processes that are affected by water stress in plants (12,19). Tissues that have been subjected to water stress generally show a reduction in protein synthesis as measured by amino acid incorporation (3, 13,18).…”

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Water Stress and Protein Synthesis

Dhindsa

Cleland²

1975

Plant Physiol.

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Water stress causes a reduction in hydrostatic pressure and can cause an increase in abscisic acid in plant tissues. To assess the possible role of abscisic acid and hydrostatic pressure in water stress effects, we have compared the effects of water stress, abscisic acid, and an imposed hydrostatic pressure on the rate and pattern of protein synthesis in Avena coleoptiles. Water stress reduces the rate and changes the pattern of protein synthesis as judged by a double labeling ratio technique. Abscisic acid reduces the rate but does not alter the pattern of protein svnthesis. Gibberellic acid reverses the abscisic acidinduced but not the stress-induced inhibition of protein synthesis. The effect of hydrostatic pressure depends on the gas used. With a 19: 1 N2-air mixture, the rate of protein synthesis is increased in stressed but not in turgid tissues. An imposed hydrostatic pressure alters the pattern of synthesis in stressed tissues, but does not restore the pattern to that found in turgid tissues. Because of the differences in response, we conclude that water stress does not affect protein synthesis via abscisic acid or reduced hydrostatic pressure.Protein synthesis is one of the biochemical processes that are affected by water stress in plants (12,19 Seattle, Washinigtoni 98195 hydrostatic pressure in the stress-induced changes in protein synthesis, we have compared the effects of water stress, ABA, and hydrostatic pressure on the rate and pattern of protein synthesis in Avena coleoptiles. We will show here that each agent exerts its own distinct effects on protein synthesis. MATERIALS AND METHODSThe plant material consisted of 1-cm sections cut from 2.5-to 3.2-cm defoliated coleoptiles of Avena sativa, cv. Victory. Seedlings were grown and sections were prepared by methods already described (6). Sections were preincubated for 1.5 hr before the start of any treatment. All solutions contained 2.5 mM potassium-maleate buffer, pH 4.7. with addition as osmoticum of 0.3 M mannitol (Difco) or 21% (w/w) Carbowax-4000 (Mann) when stress was desired.The incorporation of 'H-leucine into total proteins was used to measure the quantitative effects of water stress on protein synthesis. The double labeling ratio technique coupled with gel electrophoresis was used to study the qualitative effects of water stress on protein synthesis patterns. Details of both of these techniques are presented in an accompanying paper (7). It should be remembered that in the double labeling ratio technique, two types of protein mixtures are used in each experiment. The first (control mix) consisted of proteins labeled with C-and 3H-leucine under identical conditions (either no osmoticum or osmoticum in both). The second mixture (treat mix) consisted of proteins labeled with "C-leucine under control conditions (i.e. no osmoticum) and proteins labeled with 'H-leucine under different conditions (e.g. + osmoticum). When the "'C/;H ratio for the gels was calculated, the ratio was expected to be nearly identical for all slices of the contr...

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