Rapid determination of free proline for water-stress studies
TL;DR: In this article, a simple colorimetric determination of proline in the 0.1 to 36.0 μmoles/g range of fresh weight leaf material was presented.
Abstract: Proline, which increases proportionately faster than other amino acids in plants under water stress, has been suggested as an evaluating parameter for irrigation scheduling and for selecting drought-resistant varieties. The necessity to analyze numerous samples from multiple replications of field grown materials prompted the development of a simple, rapid colorimetric determination of proline. The method detected proline in the 0.1 to 36.0 μmoles/g range of fresh weight leaf material.
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TL;DR: The physiological and biochemical parameters measured indicate the UV-B light has stronger stress effectors than drought on the growth of seedlings of both species.
Abstract: It emerged recently that there is an inter-relationship between drought and ultraviolet-B (UV-B) radiation in plant responses, in that both stresses provoke an oxidative burst. The purpose of this investigation was to compare the effects and interaction of drought and UV-B in wheat and pea. The absence of changes in relative leaf water content (RWC) after UV-B treatments indicate that changes in water content were not involved. RWC was the main factor resulting in reduced growth in response to drought. Increases in anthocyanin and phenols were detected after exposure to UV-B. The increases do not appear to be of sufficient magnitude to act as a UV-B screen. UV-B application caused greater membrane damage than drought stress, as assessed by lipid peroxidation as well as osmolyte leakage. An increase in the specific activities of antioxidant enzymes was measured after UV-B alone as well as after application to droughted plants. Proline increased primarily in drought-stressed pea or wheat. Proline may be the drought-induced factor which has a protective role in response to UV-B. The physiological and biochemical parameters measured indicate the UV-B light has stronger stress effectors than drought on the growth of seedlings of both species. The two environmental stresses acted synergistically to induce protective mechanisms in that pre-application of either stress reduced the damage caused by subsequent application of the other stress.
1,538 citations
TL;DR: Proline (Pro) accumulation has been correlated with tolerance to drought and salinity stresses in plants and overproduction of Pro in plants may lead to increased tolerance against these abiotic stresses, suggesting that activity of the first enzyme of the pathway is the rate-limiting factor in Pro synthesis.
Abstract: Proline (Pro) accumulation has been correlated with tolerance to drought and salinity stresses in plants. Therefore, overproduction of Pro in plants may lead to increased tolerance against these abiotic stresses. To test this possibility, we overexpressed in tobacco the mothbean [delta]-pyrroline-5-carboxylate synthetase, a bifunctional enzyme able to catalyze the conversion of glutamate to [delta]-pyrroline-5-carboxylate, which is then reduced to Pro. The transgenic plants produced a high level of the enzyme and synthesized 10- to 18-fold more Pro than control plants. These results suggest that activity of the first enzyme of the pathway is the rate-limiting factor in Pro synthesis. Exogenous supply of nitrogen further enhanced Pro production. The osmotic potentials of leaf sap from transgenic plants were less decreased under water-stress conditions compared to those of control plants. Overproduction of Pro also enhanced root biomass and flower development in transgenic plants under drought-stress conditions. These data demonstrated that Pro acts as an osmoprotectant and that overproduction of Pro results in the increased tolerance to osmotic stress in plants.
1,351 citations
TL;DR: In this article, the authors show that treatment with antioxidants makes the plant tolerant against water stress by modulating the endogenous levels of H2O2 and ascorbic acid in stressed tissue.
Abstract: Vigna cutjang Endl. cv. Pusa Barsati seedlings, subjected to increasing degrees of water stress (−0.5, −1.0, −1,5 MPa), produced an approximately proportional increase in glycolate oxidase activity, hydrogen peroxide (H2O2) and proline content but a decrease in catalase activity, ascorbic acid and protein content. Leaf water potential (leaf ψ) and relative water content (RWC) were also lowered with increasing stress. Pretreatment with l-cysteine and reduced glutathione (10-3 M) decreased glycolate oxidase activity, H2O2 content, ascorbic acid oxidase activity, proline content and also slightly improved the water status of leaves stressed (−1.0 MPa) for 2 days. Pretreatment of non-stressed seedlings with these antioxidants had little or no effect. These studies indicate that treatment with antioxidants makes the plant tolerant against water stress by modulating the endogenous levels of H2O2 and ascorbic acid in stressed tissue.
1,145 citations
TL;DR: The results demonstrate that with a combination of breeding and transgenic plants it could be possible to produce salt-tolerant crops with far fewer target traits than had been anticipated and the utility of such a modification in preserving the quality of the fruit.
Abstract: ++ antiport were able to grow, flower, and produce fruit in the presence of 200 mM sodium chloride. Although the leaves accumulated high sodium concentrations, the tomato fruit displayed very low sodium content. Contrary to the notion that multiple traits introduced by breeding into crop plants are needed to obtain salt-tolerant plants, the modification of a single trait significantly improved the salinity tolerance of this crop plant. These results demonstrate that with a combination of breeding and transgenic plants it could be possible to produce salt-tolerant crops with far fewer target traits than had been anticipated. The accumulation of sodium in the leaves and not in the fruit demonstrates the utility of such a modification in preserving the quality of the fruit. RESEARCH ARTICLE Agricultural productivity is severely affected by soil salinity, and the damaging effects of salt accumulation in agricultural soils have influenced ancient and modern civilizations. Much research is aimed toward the breeding of crop cultivars with improved salt tolerance. One school of thought has concluded that salt tolerance will be achieved only after pyramiding several characteristics in a single genotype, whereas each one alone could not confer a significant increase in salt tolerance 1,2 . Arguably, salt tolerance is a complex trait, and the long list of salt stress-responsive genes seems to support this 3 . However, the overexpression of a single gene recently was shown to improve salt tolerance in Arabidopsis 4 . The detrimental effects of salt on plants are a consequence of both a water deficit resulting in osmotic stress and the effects of excess sodium ions on key biochemical processes. To tolerate high levels of salts, plants should be able to use ions for osmotic adjustment and to internally distribute these ions to keep sodium away from the cytosol. The presence of large, acidic-inside, membranebound vacuoles in plant cells allows the efficient compartmentation of sodium into the vacuole through the operation of vacuolar Na
1,105 citations
TL;DR: Results show that salinity tolerance of Kharchia 65 as manifested by lower decrease in biomass and grain yield is associated with higher antioxidant activity, osmolyte concentration and potassium contents, and lower H2O2, TBARS and sodium contents than KRL 19.
1,074 citations
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TL;DR: In the present method, a modification of the procedure of Chinard (l), the interfering basic amino acids lysine, hydroxylysine, and ornithine are removed by shaking the solutions with Permutit and the method becomes entirely specific for proline when applied to protein hydrolysates, urine, or plasma.
842 citations
838 citations
TL;DR: No significant differences were found in the amino acid and protein metabolism of the 2 varieties of Bermuda grass, and it is suggested that during water stress free proline functions as a storage compound.
Abstract: The ability of Arizona Common and Coastal Bermuda grass [Cynodon dactylon (L.) Pers.] to synthesize amino acids and proteins during water stress was investigated. Amino acids were continually synthesized during the water stress treatments, but protein synthesis was inhibited and protein levels decreased.Water stress induced a 10- to 100-fold accumulation of free proline in shoots and a 2- to 6-fold accumulation of free asparagine, both of which are characteristic responses of water-stressed plants. Valine levels increased, and glutamic acid and alanine levels decreased.(14)C labeling experiments showed that free proline turns over more slowly than any other free amino acid during water stress. This proline is readily synthesized and accumulated from glutamic acid. It is suggested that during water stress free proline functions as a storage compound.No significant differences were found in the amino acid and protein metabolism of the 2 varieties of Bermuda grass.
441 citations
TL;DR: The amino acid analyses showed that turgid leaves did not accumulate prolines and that proline and methylcysteine sulfoxide accumulation was abolished by anaerobiosis, and several pathways of amino acid degradation were suggested.
Abstract: Excised leaves were incubated at various water contents to determine the effect of water status on amino acid composition. Considerable proteolysis took place during incubation with a resultant increase in each amino acid in the non-protein fraction. However, serine, proline, gamma-aminobutyric acid and methyleysteine sulfoxide were the only amino acids in which there was an accumulation (i.e., net synthesis). Serine showed a small but consistent accumulation lasting for 6 days. Proline showed a greater accumulation but this ceased after 2 days.To learn more about the control of the proline accumulation during wilting, turgid and wilted leaves were incubated under aerobic and anaerobic conditions. The amino acid analyses showed that turgid leaves did not accumulate proline and that proline and methylcysteine sulfoxide accumulation was abolished by anaerobiosis. With other amino acids, relative concentration changes between wilted and non-wilted leaves were less striking than the difference between aerobic and anaerobic conditions.Under anaerobic conditions there was an increase in alanine and a large increase in gamma-aminobutyric acid which were not evident in air. Serine, aspartic acid, glutamic acid, and glutamine disappeared more rapidly and glycine disappeared less rapidly under anaerobic than under aerobic conditions.On the basis of these results, several pathways of amino acid degradation were suggested.
87 citations
TL;DR: A method applicable to protein samples was developed and the only compound found to interfere appreciably was a hydroxyproline.
Abstract: 1. The conditions required for sensitive and specific colorimetric determination of proline with acidified ninhydrin were investigated. 2. A method applicable to protein samples was developed. 3. The only compound found to interfere appreciably was a hydroxyproline.
52 citations