Effects of saline and osmotic stress on proline and sugar accumulation in Populus euphratica in vitro.
01 Dec 2000-Plant Cell Tissue and Organ Culture (Kluwer Academic Publishers)-Vol. 63, Iss: 3, pp 199-206
TL;DR: It is suggested that accumulated proline and sugars promote osmotic and salt tolerance and the effects of salt and mannitol in the medium on prolines and sugar accumulation were investigated in two poplar species, P. euphratica and P. tomentosa.
Abstract: The use of in vitro shoot cultures to evaluate osmotic and salt tolerance and the effects of salt and mannitol in the medium on proline and sugar accumulation were investigated in two poplar species, P. euphratica and P. alba cv. Pyramidalis × P. tomentosa. Shoot length, leaf number, whole plant dry weight, and the accumulation of proline and total soluble sugars in leaves were quantified after 2 weeks. All P.
euphratica plantlets survived at all levels of mannitol and NaCl, while the mortality of P. alba cv. Pyramidalis × P. tomentosa increased both at the mannitol and the NaCl treatments. A significant increase in proline accumulation was observed in both young and mature P. euphratica leaves at 200 mM mannitol and above, and at 150 mM NaCl and above. The total soluble sugar content increased in young P. euphratica leaves at 250 mM NaCl; however, it decreased in the mature leaves. Similar increases of the total soluble sugar content were not seen in P. alba cv. Pyramidalis × P. tomentosa plants in response to either mannitol or NaCl treatment. Our results suggest that accumulated proline and sugars promote osmotic and salt tolerance. The effects of accumulated proline and total soluble sugars on leaves are discussed in relation to growth and osmotic adjustment.
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TL;DR: In this paper, the authors review recent advances on silicon uptake, transport, and accumulation in plants and how silicon alleviates salinity toxicity and drought stress, and the major points are the following: (1) both passive and active silicon uptake may coexist in plants; (2) although silicon transporters have been identified in some plants, the process of silicon transport needs further clarification; (3) the mechanisms for silicon-mediated tolerance of salinity and drought have been extensively investigated at both physiological and biochemical levels.
Abstract: Soil salinity and drought are major abiotic factors that limit crop growth and productivity worldwide. Indeed, soil salinity and drought disrupt the cellular ionic and osmotic balance. Although silicon (Si) is generally considered nonessential for plant growth and developments, Si uptake by plants can alleviate both biotic and abiotic stresses. Silicon application could therefore improve crop production under adverse climate and soil conditions. Several reports have reviewed the benefits of silicon application on crop growth, but the mechanisms of silicon action have not been systematically discussed. Here, we review recent advances on silicon uptake, transport, and accumulation in plants and how silicon alleviates salinity toxicity and drought stress. The major points are the following: (1) both passive and active silicon uptake may coexist in plants; (2) although silicon transporters have been identified in some plants, more silicon transporters remain to be identified, and the process of silicon transport needs further clarification; (3) the mechanisms for silicon-mediated tolerance of salinity and drought have been extensively investigated at both physiological and biochemical levels. The physiological aspects include increasing water uptake by roots, maintaining nutrient balance, decreasing water loss from leaves, and promoting photosynthetic rate. At the biochemical level, silicon may improve antioxidant defense abilities by increasing the activities of antioxidant enzymes and the contents of non enzymatic antioxidants; silicon may also contribute to osmotic adjustment and increase photosynthetic enzymatic activities; and (4) silicon can regulate the levels of endogenous plant hormones under stress conditions, whereas silicon involvement in signaling and regulation of gene expression related to increasing stress tolerance remains to be explored.
417 citations
Cites background from "Effects of saline and osmotic stres..."
...Watanabe et al. (2000) also found that the stressors NaCl and mannitol induce proline accumulation in Populus euphratica leaves....
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TL;DR: It is suggested that seed priming with chitosan may improve the speed of germination of maize seed and benefit for seedling growth under low temperature stress.
Abstract: Low temperature stress during germination and early seedling growth is an important constraint of global production of maize. The effects of seed priming with 0.25%, 0.50%, and 0.75% (w/v) chitosan solutions at 15 °C on the growth and physiological changes were investigated using two maize (Zea mays L.) inbred lines, HuangC (chilling-tolerant) and Mo17 (chilling-sensitive). While seed priming with chitosan had no significant effect on germination percentage under low temperature stress, it enhanced germination index, reduced the mean germination time (MGT), and increased shoot height, root length, and shoot and root dry weights in both maize lines. The decline of malondialdehyde (MDA) content and relative permeability of the plasma membrane and the increase of the concentrations of soluble sugars and proline, peroxidase (POD) activity, and catalase (CAT) activity were detected both in the chilling-sensitive and chilling-tolerant maize seedlings after priming with the three concentrations of chitosan. HuangC was less sensitive to responding to different concentrations of chitosan. Priming with 0.50% chitosan for about 60∼64 h seemed to have the best effects. Thus, it suggests that seed priming with chitosan may improve the speed of germination of maize seed and benefit for seedling growth under low temperature stress.
381 citations
Cites background from "Effects of saline and osmotic stres..."
...Accumulation of organic compounds such as proline in the cytoplasm also plays an important role in osmotic adjustment in plants (Watanabe et al., 2000)....
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TL;DR: Drought successively induced shoot growth cessation, stomatal closure, moderate increases in oxidative stress-related compounds, loss of CO2 assimilation, and root growth reduction, indicating that acclimation was dominant over injury.
Abstract: The responses of Populus euphratica Oliv. plants to soil water deficit were assessed by analyzing gene expression, protein profiles, and several plant performance criteria to understand the acclimation of plants to soil water deficit. Young, vegetatively propagated plants originating from an arid, saline field site were submitted to a gradually increasing water deficit for 4 weeks in a greenhouse and were allowed to recover for 10 d after full reirrigation. Time-dependent changes and intensity of the perturbations induced in shoot and root growth, xylem anatomy, gas exchange, and water status were recorded. The expression profiles of approximately 6,340 genes and of proteins and metabolites (pigments, soluble carbohydrates, and oxidative compounds) were also recorded in mature leaves and in roots (gene expression only) at four stress levels and after recovery. Drought successively induced shoot growth cessation, stomatal closure, moderate increases in oxidative stress-related compounds, loss of CO2 assimilation, and root growth reduction. These effects were almost fully reversible, indicating that acclimation was dominant over injury. The physiological responses were paralleled by fully reversible transcriptional changes, including only 1.5% of the genes on the array. Protein profiles displayed greater changes than transcript levels. Among the identified proteins for which expressed sequence tags were present on the array, no correlation was found between transcript and protein abundance. Acclimation to water deficit involves the regulation of different networks of genes in roots and shoots. Such diverse requirements for protecting and maintaining the function of different plant organs may render plant engineering or breeding toward improved drought tolerance more complex than previously anticipated.
364 citations
Cites background from "Effects of saline and osmotic stres..."
...Pro accumulated in leaves of P. euphratica in response to osmotic stress during earlier studies (Watanabe et al., 2000; Ottow et al., 2005)....
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...Laboratory studies showed that it is able to cope with osmotic stress imposed by NaCl and mannitol (Watanabe et al., 2000; Gu et al., 2004)....
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TL;DR: Investigation of physiological mechanisms enabling Populus euphratica Olivier to cope with stress caused by salinity found decreases in apoplastic and vacuolar Ca2+ combined with suppression of calcineurin B-like protein transcripts suggest that Na+ adaptation required suppression of calcium-related signaling pathways.
Abstract: Populus euphratica Olivier is known to exist in saline and arid environments. In this study we investigated the physiological mechanisms enabling this species to cope with stress caused by salinity. Acclimation to increasing Na+ concentrations required adjustments of the osmotic pressure of leaves, which were achieved by accumulation of Na+ and compensatory decreases in calcium and soluble carbohydrates. The counterbalance of Na+/Ca2+ was also observed in mature leaves from field-grown P. euphratica trees exposed to an environmental gradient of increasing salinity. X-ray microanalysis showed that a primary strategy to protect the cytosol against sodium toxicity was apoplastic but not vacuolar salt accumulation. The ability to cope with salinity also included maintenance of cytosolic potassium concentrations and development of leaf succulence due to an increase in cell number and cell volume leading to sodium dilution. Decreases in apoplastic and vacuolar Ca2+ combined with suppression of calcineurin B-like protein transcripts suggest that Na+ adaptation required suppression of calcium-related signaling pathways. Significant increases in galactinol synthase and alternative oxidase after salt shock and salt adaptation point to shifts in carbohydrate metabolism and suppression of reactive oxygen species in mitochondria under salt stress.
271 citations
Cites background from "Effects of saline and osmotic stres..."
...It grows under unfavorable conditions such as saline and alkaline soils (Kang et al., 1996; Watanabe et al., 2001; Chen et al., 2002)....
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...It is known that P. euphratica increases Pro under salt stress (Watanabe et al., 2001; see Supplemental Fig....
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TL;DR: Of the obtained ESTs, 98% were found in the sequenced P. trichocarpa genome and 74% in other Populus EST collections, which implies that the P. euphratica genome does not contain different genes per se, but that regulation of gene expression might be different and that P. ecstatica expresses a different set of genes that contribute to adaptation to saline growth conditions.
Abstract: Background: Plants growing in their natural habitat represent a valuable resource for elucidating mechanisms of acclimation to environmental constraints. Populus euphratica is a salt-tolerant tree species growing in saline semi-arid areas. To identify genes involved in abiotic stress responses under natural conditions we constructed several normalized and subtracted cDNA libraries from control, stress-exposed and desert-grown P. euphratica trees. In addition, we identified several metabolites in desert-grown P. euphratica trees. Results: About 14,000 expressed sequence tag (EST) sequences were obtained with a good representation of genes putatively involved in resistance and tolerance to salt and other abiotic stresses. A P. euphratica DNA microarray with a uni-gene set of ESTs representing approximately 6,340 different genes was constructed. The microarray was used to study gene expression in adult P. euphratica trees growing in the desert canyon of Ein Avdat in Israel. In parallel, 22 selected metabolites were profiled in the same trees. Conclusion: Of the obtained ESTs, 98% were found in the sequenced P. trichocarpa genome and 74% in other Populus EST collections. This implies that the P. euphratica genome does not contain different genes per se, but that regulation of gene expression might be different and that P. euphratica expresses a different set of genes that contribute to adaptation to saline growth conditions. Also, all of the five measured amino acids show increased levels in trees growing in the more saline soil.
238 citations
References
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TL;DR: In vivo redox biosensing resolves the spatiotemporal dynamics of compartmental responses to local ROS generation and provide a basis for understanding how compartment-specific redox dynamics may operate in retrograde signaling and stress 67 acclimation in plants.
Abstract: In experiments with tobacco tissue cultured on White's modified medium (basal meditmi hi Tnhles 1 and 2) supplemenk'd with kiticthi and hidoleacctic acid, a slrikin^' fourlo (ive-told intTease iu yield was ohtaitu-d within a three to Tour week j^rowth period on addition of an aqtteotis exlrarl of tobacco leaves (Fi^'ures 1 and 2). Subse(iueutly it was found Ihiit this jnoniotiou oi' f^rowih was due mainly though nol entirely to inorj^auic rather than organic con.stitttenls in the extract. In the isolation of Rrowth factors from plant tissues and other sources inorj '̂anic salts are fre(|uently carried along with fhe organic fraclioits. When tissue cultures are used for bioassays, therefore, il is necessary lo lake into account increases in growth which may result from nutrient elements or other known constituents of the medium which may he present in the te.st materials. To minimize interference trom rontaminaitis of this type, an altempt has heen made to de\\eh)p a nieditmi with such adequate supplies of all re(iuired tnineral nutrients and cotntnott orgattic cottslitueitls that no apprecial»le change in growth rate or yield will result from the inlroduclion of additional amounts in the range ordinarily expected to be present in tnaterials to be assayed. As a point of referetice for this work some of the culture media in mc)st common current use will he cotisidered briefly. For ease of comparis4)n Iheir mineral compositions are listed in Tables 1 and 2. White's nutrient .solution, designed originally for excised root cultures, was based on Uspeuski and Uspetiskaia's medium for algae and Trelease and Trelease's micronutrieni solution. This medium also was employed successfully in the original cttltivation of callus from the tobacco Iiybrid Nicotiana gtauca x A', tanijadorffii, atitl as further modified by White in 194̂ ^ and by others it has been used for the
63,098 citations
"Effects of saline and osmotic stres..." refers background in this paper
...In 1/2 MS medium, the major inorganic components were reduced to one half the levels in MS medium (Murashige and Skoog, 1962)....
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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.
15,328 citations
"Effects of saline and osmotic stres..." refers methods in this paper
...The free proline content in the ethanol-soluble fractions was determined by a colorimetric method using ninhydrin (Bates et al., 1973)....
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01 Jun 2000
TL;DR: Evidence for plant stress signaling systems is summarized, some of which have components analogous to those that regulate osmotic stress responses of yeast, some that presumably function in intercellular coordination or regulation of effector genes in a cell-/tissue-specific context required for tolerance of plants.
Abstract: ▪ Abstract Plant responses to salinity stress are reviewed with emphasis on molecular mechanisms of signal transduction and on the physiological consequences of altered gene expression that affect biochemical reactions downstream of stress sensing. We make extensive use of comparisons with model organisms, halophytic plants, and yeast, which provide a paradigm for many responses to salinity exhibited by stress-sensitive plants. Among biochemical responses, we emphasize osmolyte biosynthesis and function, water flux control, and membrane transport of ions for maintenance and re-establishment of homeostasis. The advances in understanding the effectiveness of stress responses, and distinctions between pathology and adaptive advantage, are increasingly based on transgenic plant and mutant analyses, in particular the analysis of Arabidopsis mutants defective in elements of stress signal transduction pathways. We summarize evidence for plant stress signaling systems, some of which have components analogous to t...
4,596 citations
"Effects of saline and osmotic stres..." refers background in this paper
...…of the osmotic potential in the tissues of plants exposed to low water availability and is a common response in some herbaceous and woody plant species to water deficits or to osmotic stress induced by high ion accumulation in the soil (Morgan, 1984; Gebre et al., 1997; Hasegawa et al., 2000)....
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...some herbaceous and woody plant species to water deficits or to osmotic stress induced by high ion accumulation in the soil (Morgan, 1984; Gebre et al., 1997; Hasegawa et al., 2000)....
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TL;DR: An analysis of major U.S. crops shows that there is a large genetic potential for yield that is unrealized because of the need for better adaptation of the plants to the environments in which they are grown.
Abstract: An analysis of major U.S. crops shows that there is a large genetic potential for yield that is unrealized because of the need for better adaptation of the plants to the environments in which they are grown. Evidence from native populations suggests that high productivity can occur in these environments and that opportunities for improving production in unfavorable environments are substantial. Genotypic selection for adaptation to such environments has already played an important role in agriculture, but the fundamental mechanisms are poorly understood. Recent scientific advances make exploration of these mechanisms more feasible and could result in large gains in productivity.
3,715 citations
"Effects of saline and osmotic stres..." refers background in this paper
...Environmental stresses in these semiarid areas, mainly drought and salinity, limit growth and productivity of most plant species (Boyer, 1982)....
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...Environmental stresses in these semiarid areas, mainly drought and salinity, limit growth and productivity of most plant species ( Boyer, 1982 )....
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1,539 citations
"Effects of saline and osmotic stres..." refers background in this paper
...…of the osmotic potential in the tissues of plants exposed to low water availability and is a common response in some herbaceous and woody plant species to water deficits or to osmotic stress induced by high ion accumulation in the soil (Morgan, 1984; Gebre et al., 1997; Hasegawa et al., 2000)....
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...some herbaceous and woody plant species to water deficits or to osmotic stress induced by high ion accumulation in the soil (Morgan, 1984; Gebre et al., 1997; Hasegawa et al., 2000)....
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