• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.1
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• pp.51-57
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• 2000

Changes in the proline accumulation of ten-day-old seedlings of Vigna angularis in response to NaCl treatment were monitored. The proline content increased gradually both with an increase in the exposure time to salt stress and in a concentration-dependent manner. The increased proline accumulation was stronger in the shoots than in the roots. The salt stress by itself resulted in a significant inhibition of the chlorophyll content. Pre-treatment with proline before salinization lasting 48 h did not significantly affect the endogenous proline level in the roots, in contrast, a considerable increase of proline was observed in the shoots. The application of exogenous proline to the seedlings increased the endogenous proline content and improved the root and shoot growth under saline conditions. Detached leaves also exhibited an increased proline level in response to the applied NaCl, however, at a lower magnitude than in the intact seedlings. The proline alleviated the inhibitory effect of the NaCl in a concentration-dependent manner, thereby suggesting that salinity is a strong inducer of proline accumulation. In addition, abscisic acid eliminated the inhibitory effect of the salt salinity, thereby indicating a protective role on salinity stress and a regulatory role in proline synthesis. Accordingly, it would appear that proline may be involved in salt tolerance.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.10 no.S_4
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• pp.189-196
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• 2001

The blue green alga, Microcystis aeruginosa, was found to accumulate proline under the stressful concentration of cupric ions. The changes of proline level in Microcystis aeruginosa in response to copper(Cu) have been monitored and the function of the accumulated proline was studied with respect to its effect on Cu uptake. Exposure of Microcystis aeruginosa elevated concentrations of Cu led to accumulation of fee proline depending on the concentrations of the metal in the external medium. The greater the toxicity or accumulation of the metal, the higher the amount of proline in algal cells were found. When proline was exogenously supplied prior to Cu treatment, the absorption of Cu was markedly reduced. When exogenous proline was supplied after Cu treatment, it resulted in a remarkable desorption of the adsorbed Cu immediately after the addition of proline. Pretreatment of Microcystis aeruginosa with proline counteracted with metal-induced lipid peroxidation. The results of the present study showed a protective elect of proline on metal toxicity through inhibition of lipid peroxidation and suggested that the accumulation of proline may be related to the tolerance mechanism for dealing with Cu stress.

• BMB Reports
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• v.42 no.1
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• pp.28-34
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• 2009

To understand the molecular mechanism underlying proline accumulation in Brassica napus, cDNAs encoding ${\Delta}^1$-pyrroline-5-carboxylate synthetase (BnP5CS), ornithine $\delta$-aminotransferase (BnOAT) and proline dehydrogenase (BnPDH) were isolated and characterized. Southern blot analysis of BnP5CSs in B. napus and its diploid ancestors suggested a gene loss may have occurred during evolution. The expression of BnP5CS1 and BnP5CS2 was induced, while the expression of BnPDH was inhibited under salt stress, ABA treatment and dehydration, prior to proline accumulation. The upregulation of BnOAT expression was only detected during prolonged severe osmotic stress. Our results indicate that stress-induced proline accumulation in B. napus results from the reciprocal action of activated biosynthesis and inhibited proline degradation. Whether the ornithine pathway is activated depends on the severity of stress. During development, proline content was high in reproductive organs and was accompanied by markedly high expression of BnP5CS and BnPDH, suggesting possible roles of proline during flower development.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.1
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• pp.57-65
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• 1979

In order to find the physiology of responess In order to find the physiology of responses and mechanisms of the actumlation of free proline at low temperatures and water stress. the temperature range, the effect of prolonged exposure to low temperatures, the light-dependence of proline accumulation in barle was significantly lower than in wheat. Proline accumulation at 5\circ C without water stress was shown to be light-dependent. Proline accumulation by water stress was not light-dependent at 2$0^{\circ}C$ but at 5$^{\circ}C$.

• Journal of Plant Biotechnology
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• v.37 no.4
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• pp.529-538
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• 2010

Proline accumulates in plants under environmental stresses including saline stress and alkaline stress. Here, we investigated the responses to two different stresses, saline stress (200 mM NaCl) and alkaline stress (100 mM $Na_2CO_3$) in two Leymus chinensis (Trin.) genotypes, LcWT07 and LcJS0107, and effects of exogenous proline on the activities of antioxidant enzymes. Both saline stress and alkaline stress significantly induced the accumulation of proline in leaves of the two genotypes after 96 h, and alkaline stress caused a transient and significant increase in LcJS0107 plants at 6 h. A reduction in the activities of catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11), but not in the activity of superoxide dismutase (SOD, EC 1.15.1.1), was detected in plants exposed to saline and alkaline stresses. Remarkable decrease in relative water contents (RWC) was found in 144 h stressed plants. However, lipid peroxidation estimated by malonyldialdehyde (MDA) content in leaves remained relatively stable. With the addition of exogenous proline, it did not cause changes of proline levels in two genotypes, but combined with saline or alkaline stress, the exogenous application of proline significantly induced proline accumulation after even short treatment periods. Combined with salt stress, the exogenous application also increased the activities of CAT and APX. These results indicated that exogenous proline not only increases proline levels in vivo as a osmotic adjustment under stress, but mitigates the detrimental effects of saline and alkaline stresses by increasing the activities of antioxidant enzymes.

• Journal of Plant Biology
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• v.34 no.3
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• pp.185-190
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• 1991

Hypocotyl-derived callus cultures of Brassica pekinensis cv. Chungseng were grown on Murashige-Skoog medium containing NaCl, Na2SO4 and mannitol to clarify the effect of salts on callus growth, proline accumulation and water relations. Na2SO4 was more inhibitory than NaCl when survival rate, growth and fresh:dry weight ratios of established callus were measured. Fresh weight in 0.25% NaCl treatment was more than twice as increasable in comparison to the same concentration of Na2SO4 or control. Proline concentration was increased on either salt, attained at highest levels at the 5th subculture, and fluctuated as affected by both salts or mannitol. Concentrations of redeucing sugars were sharply increased after 2 or 3 times of subculture and decreased by increasing subculture. The water and osmotic potential in callus reached a maximum negative value after two weeks in culture, regardless of salt type and mannitol and tugor remained relatively constant on both salt and mannitol treatments.

• Journal of the East Asian Society of Dietary Life
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• v.5 no.2
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• pp.19-26
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• 1995

Staphylococcus aureus, the most salt-tolerant nonhalophilic bacterium, is the only foodborne pathogen that is able to grow at a levels below 0.90. The fundamental osmorgulatory strategy used by this organism involves the accumulation of intracellular compatible solutes such as proline or glycine betaine which are accumulated by transport and act as osmoregulators in cells. In this study, levels of proline transport systems and glycine betaine transport system of S. aureus were examined when cells are grown at high osmolarity. The levels of all three transport systems within S. aureus were elevated at high osmolarity and the most dramatic increase was found for the low-affinity proline transport system. However, in 5mM glycine betaine-supplemented medium, the level of the low-affinity proline transport system did not become elevated when cultures were grown at high osmolarity. The metabolic fate of the accumulated proline and glycine getaine was investigated by thin-layer chromatography an found to be not metabolized by S. aureus.

• Journal of Environmental Science International
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• v.11 no.11
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• pp.1173-1181
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• 2002

The present study was undertaken to investigate the effect of low temperature and salicylic acid(SA) on the chilling tolerance of acclimated and nonacclimated cucumber(Cucurmis sativus L.) seedlings. The acclimation phenomenon was characterized in chilling-sensitive cucumber seedlings and found to have a significant effect on the survival and shoot dry weights. The injuries experienced by the acclimated seedlings in the third leaf stage were on average smaller by half than those experienced by the nonacclimated seedlings. Chilling also caused a large increase in the free proline levels, regardless of the acclimation status. Exogenous treatment with SA(0.5mM) resulted in improved growth and survival of the nonacclimated chilled seedlings, indicating that SA induced chilling tolerance and SA and acclimation had common effects. The application of cycloheximide in the presence of SA restored the acclimation-induced chilling tolerance. The elevated proline level observed in the cold-treated and SA-treated plants was more pronounced in the light than in the dark at a chilled temperature, indicating that endogenous proline may play a role in chilling tolerance by stabilizing the water status in response to chilling. From these results it is suggested that SA provided protection against low-temperature stress by increasing the proline accumulation, and pre-treatment with SA may induce antioxidant enzymes leading to increased chilling tolerance.

• Journal of Plant Biotechnology
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• v.5 no.3
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• pp.157-161
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• 2003

Proline is known as an osmoprotectant accumulating in response to salt and dehydration stresses. An increased level of proline is achieved by either an induced synthesis or a reduced degradation of proline. In an attempt to increase salt tolerance in carrot, a P5CS gene from mothbean was introduced via an Agrobacterium-mediated transformation. The resulting carrot cells and the regenerated plants containing the transgene showed increased levels of proline compared to nontransgenics. The transgenic cell line, Pj2 showed about 6 times increased degree of tolerance determined by relative growth after a treatment in 250 mM NaCl. In facts, due to the retarded growth shown in non-saline condition, Pj2 cells grow only about 1.2 times better than nontransgenic control under salt stress condition. Taken together, it appears that a P5CS is a key enzyme in proline biosynthesis and the increased accumulation of proline by overexpression of the enzyme is enough to enhance tolerance to salt stress in carrot.

• Journal of Plant Biotechnology
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• v.46 no.4
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• pp.331-337
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• 2019

Digitaria exilis L. is an under-utilized crop with high nutritional and medicinal values. It thrives in and is well-adapted to arid areas with low soil nutrients. Using biochemical markers, this study investigates the mechanisms by which D. exilis responds to osmotic stress. Three accessions Dinat Iburua (DIN), Jakah Iburua (JAK) and Jiw Iburua (JIW) were collected from National Cereal Research Institute, Niger State. Two accessions, NG/11/JD/061 and NG/11/JD/062 were also collected from National Centre for Genetic Resources and Biotechnology, Ibadan. Murashige and Skoog medium of approximately 1.2 L was supplemented with polyethylene glycol 6000 to create osmotic pressures of -9.29, -13.93, -20.13, -26.32, -32.51, and 0 MPa (control). Sterilized seeds were inoculated in the medium and placed in the growth room for 4 weeks. Proline accumulation was significantly high in all JAK plants under osmotic stress. Proline and ascorbate peroxidase (p<0.05) activities were directly correlated, thus reinforcing the survivability of JAK during stress. Catalase (CAT) activity was also significantly induced in JAK under osmotic stress, which synergistically improved its tolerability. As a result, >50% of OH-, H₂O₂, and NO radicals were scavenged. However, other accessions including DIN, NG061, NG062, and JIW showed variations in their responses to different levels of osmotic stress, although not significant. Therefore, JAK possesses a well-equipped free radical quenching system that is protected by the accumulation of the osmolyte proline; therefore, accession JAK is considered osmotolerant. CAT and superoxide dismutase activities were osmostabilized against oxidative stress by proline.