Salinity Effects on Water Potential Components and Bulk Elastic Modulus of <i>Alternanthera philoxeroides</i> (Mart.) Griseb.

Bolaños, J.; Longstreth, David J.

doi:10.1104/pp.75.2.281

Cited by 57 publications

(33 citation statements)

References 17 publications

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“…Under isoosmotic conditions, turgor homeostasis in expanding leaves of cotton was also apparent (Fig. 1) and was likely in the expanding leaves of peanut, given that cell turgor equals the difference between total water potential and Wi, assuming that the total water potential of fully turgid leaves approximated the water potential of the rooting medium (2) and that sap osmotic pressure approximated 1ri.…”

Section: Discussionmentioning

confidence: 99%

Isoosmotic Regulation of Cotton and Peanut at Saline Concentrations of K and Na

Lauter¹,

Meiri²,

Shuali³

1988

Plant Physiol.

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ABSTRACIPeanut (Arachis hypogaea L.) and cotton (Gossypium hirsutum) plants were grown for 4 weeks in saline, isoosmotic rooting substrates with different proportions of K and Na. Isoosmotic media did not affect growth (except at the highest external K concentrations) or estimates of intracellular osmotic pressure in expanding leaves (i.e. osmotic pressure of leaf sap and intracellular osmotic pressure as calculated from pressurevolume curves). In expanded leaves, an increase in the proportion of external K increased sap osmotic pressure. The sum of [K+Na+ClJ in the sap of expanding and expanded leaves accounted for the effect of isoosmotic media on the concentration of osmolytes with high electrical conductance, so the difference between sap osmotic pressure and [K+Na+ClJ accounted for the concentration of osmolytes with low conductance. In expanding leaves, an increase in the proportion of external K increased [K+Na+CIl and decreased the concentration of osmolytes with low conductance. In expanded leaves, an increase in the proportion of external K increased [K+Na+Cli to approximately the same extent as sap osmotic pressure. Isoosmotic regulation was apparent in expanding leaves but not evident in expanded leaves. This suggests a turgor homeostat which can influence the concentration of organic solutes in expanding leaves but cannot control the import of inorganic solutes from a rooting medium nor the total production of organic solutes in plants with a low sink:source ratio.In response to salinity or water deficit, the tissues of some higher plants undergo complete osmotic adjustment, i.e., accumulate solutes such that A7r2 and cell turgor are restored to their original values (24). Osmotic adjustment is considered to be a form of adaptation to salt stress and water deficit (10), but it is not known if tissues of nonhalophytic angiosperms contain a turgor homeostat (9, 23), as do many species of halophytic algae, which can detect changes in cell turgor and subsequently signal turgor restoration (5). Low growth rate and high solute availability will increase ri and turgor in the absence ofa turgor regulatory mechanism (5,23 (23).The capacity of some higher plants to maintain a particular Wi and cell turgor by the use of different solutes a the same ir0, defined to be isoosmotic regulation (27), has been cited as evidence for a mechanism of osmotic and turgor homeostasis (5, 14, 16). Different isoosmotic media can have a negligible effect on growth (1, 18) so that the effect of isoosmotic media on the composition of a tissue can be determined in the absence of interactions between growth rate and solute transport. However, past claims of isoosmotic regulation lack an assessment of the response of iri to the total amount of external solutes absorbed by a tissue. There are several cases in which -xi was affected by the composition of isoosmotic media (13,21,23) and in some cases ofisoosmotic regulation the differences in the total concentration of inorganic osmolytes in a tissue were not enough to significantly c...

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Section: Discussionmentioning

confidence: 99%

Isoosmotic Regulation of Cotton and Peanut at Saline Concentrations of K and Na

Lauter¹,

Meiri²,

Shuali³

1988

Plant Physiol.

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“…In contrast with the apical growth meristem in dicotyledonae, the basal meristem in grasses is less exposed to the evaporative demand of the atmosphere which may contribute to an increased water use efficiency and growth being less sensitive to an environment with a large evaporative demand. Cell walls of Poaceae halophytes are more rigid than those of halophytic dicotyledonae (Bolanos and Longstreth, 1984) with a higher elasticity. After Rozema (1991Rozema ( , 1996.…”

Section: Article In Pressmentioning

confidence: 99%

Salt tolerance of halophytes, research questions reviewed in the perspective of saline agriculture

Rozema

Schat

2013

Environmental and Experimental Botany

205

131

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“…For example, Anderson et al (2) presented evidence that freezeinduced cell water loss is slowed in a way related to the bulk mechanical properties of the tissue. In this case, and in both salt (3) and drought (1 1, 18) stress acclimation, altered cell wall elasticity was considered an important component of the adaptive response. Reports of cell wall thickening during cold acclimation (1O) are consistent with this idea.…”

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Cell Wall and Extensin mRNA Changes during Cold Acclimation of Pea Seedlings

Weiser¹,

Wallner²,

Waddell³

1990

Plant Physiol.

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During exposure to 2 OC, pea (Pisum sativum) seedlings cold acclimated to a killing temperature of -6 OC. Associated with this increase in freezing resistance was an increase in the weight of cell walls and changes in wall composition. Arabinosyl content increased by 100%, while other cell wall glycosyl residues and cellulose increased by about 20%. The cell wall hydroxyproline content increased by 80%. Arabinose and hydroxyproline are both major components of the structural cell wall glycoprotein, extensin. The increase in these components indicates that the level of extensin in the cell wall increases during cold acclimation. Northern blot analysis, using the pDC5A1 genomic clone as a probe, revealed a more than three-fold increase in total extensin mRNA during exposure to cold temperature. Specific extensin transcripts of 6.0, 4.5, 3.5, 2.6, 2.3, 1.8, and 1.5 kilobases were identified. Those at 6.0, 2.6, and 1.5 kilobases were especially promoted by low temperature treatment. The rise in extensin during cold acclimation may be regulated, at least in part, at the gene level. The possible structural role of this protein in freezing protection is discussed.During extracellular freezing, plant cells are exposed to stresses associated with dehydration and consequent volume reduction, direct effects of low temperature, and mechanical effects of extracellular ice. The plasmalemma response to protoplast freeze-thaw has been characterized by Steponkus (22) A cell wall change which could significantly alter relevant mechanical properties is the increased deposition of the glycoprotein extensin, a change known to be stress induced (27). A structural role for extensin was first proposed by Lamport and Northcote (13). The glycoprotein they discovered, later named extensin for its putative role in cessation of extension growth, was found to contain a great portion of the hydroxyproline in the cell. Extensin is viewed to contribute to the strength and rigidity of the cell wall by forming an interpeptide-linked network that is separate from, but complementary to the cellulose mesh (14).It was hypothesized that if structural changes in the cell wall increase its rigidity during acclimation, thereby possibly limiting freeze-induced cell water loss and resulting injury, then an increase in freezing resistance should occur. Data presented here quantify: cell wall weight, total glucan, noncellulosic glucan, cellulose, and glycosyl content during acclimation. A pronounced increase in arabinose content led us to suspect an increase in extensin. Cell wall hydroxyproline content and extensin mRNA were measured during acclimation to test this theory. MATERIALS AND METHODSUnless otherwise indicated, the conditions for growth, acclimation, and freezing tolerance measurement were as follows. Experiments were conducted with seedlings of Pisum sativum, cultivars 'Alaska' and 'Melrose.' In most experiments, seeds were germinated and seedlings grown in the dark at 22 C, using vermiculite moistened with deionized water. In certain ca...

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Salinity Effects on Water Potential Components and Bulk Elastic Modulus of Alternanthera philoxeroides (Mart.) Griseb.

Cited by 57 publications

References 17 publications

Isoosmotic Regulation of Cotton and Peanut at Saline Concentrations of K and Na

Isoosmotic Regulation of Cotton and Peanut at Saline Concentrations of K and Na

Salt tolerance of halophytes, research questions reviewed in the perspective of saline agriculture

Cell Wall and Extensin mRNA Changes during Cold Acclimation of Pea Seedlings

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