Proline Analogues in Melaleuca Species: Response of Melaleuca lanceolata and M. uncinata to Water Stress and Salinity

1987 ◽  
Vol 14 (6) ◽  
pp. 669 ◽  
Author(s):  
BP Naidu ◽  
GP Jones ◽  
LG Paleg ◽  
A Poljakoff-Mayber
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Compatible Solutes ◽  
Species Response ◽  
Laboratory Conditions ◽  
Relative Water ◽  
Response To Water ◽  
First Time

Fifteen species of Melaleuca and two species of Callistemon from the field were examined to determine whether they accumulated nitrogen-containing compatible solutes and, if so, which. In addition to L-proline, N-methyl-L-proline (MP) (isolated for the first time from plants), trans-4-hydroxy-N-methyl- L-proline (MHP), and N, N'-dimethyl-trans-4-hydroxy-L-proline (DHP) were found in various combinations in the 15 Melaleuca species. M. lanceolata seedlings were subjected to water or salinity stress and M. uncinata to water stress under laboratory conditions. In both species significant reductions in leaf water potential (Ψw), osmotic potential (Ψs), turgor potential (Ψp), and relative water content (RWC) were observed in response to water stress. Salinised M. lanceolata plants showed considerable osmotic adjustment and maintained Ψp comparable to that of control plants; salinity, however, decreased RWC. In response to the imposed stresses under laboratory conditions, proline and MHP levels in M. lanceolata, and MHP and DHP levels in M. uncinata, increased. In addition to possible protective or osmotic roles in vivo, these proline analogues may be useful in chemotaxonomic investigations of Melaleuca species.

Water stress conditioning of corn (Zea mays) in the field and the greenhouse

1985 ◽  
Vol 63 (4) ◽  
pp. 704-710 ◽  
Author(s):  
L. M. Dwyer ◽  
D. W. Stewart
Keyword(s):  
Zea Mays ◽  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Temperature Sensitive ◽  
Pressure Potential ◽  
Response To Water

Leaf water potential, osmotic potential, and leaf conductance were measured on corn (Zea mays L.) under water stress in the field and the greenhouse. Field-grown plants were subjected to several cycles of moderate water stress during vegetative growth, while greenhouse plants were well watered until just before the measurement period began following tasselling. In both the field and the greenhouse, leaf water potential declined at midday. Comparison of leaf water potential and osmotic potential measurements indicated that in both environments, the midday decline in leaf water potential was accompanied by a decline in osmotic potential. Since the decline in osmotic potential was greater than that accounted for by predicted volume changes resulting from normal daily dehydration, it was assumed to indicate osmotic adjustment. Despite these similarities, field-grown plants showed a greater response to water stress. Field plants underwent larger daily changes in leaf water potential and these were accompanied by larger changes in osmotic potential. As a result of this greater osmotic adjustment in the field, conductivity was higher at equivalent leaf water potentials and the critical leaf water potential was lower than in greenhouse-grown plants. In both environments, osmotic adjustment maintained leaf turgor (or pressure potential) in a narrow positive range. Although there was no direct relation between turgor potential and leaf conductivity, we hypothesize that the maintenance of a positive turgor potential during daylight hours is significant for growth since it may allow the moisture- and temperature-sensitive process of leaf expansion to proceed during the warmer daylight hours, even under moderate water stress.

Accumulation of Glycinebetaine in Chloroplasts Provides Osmotic Adjustment During Salt Stress

1986 ◽  
Vol 13 (5) ◽  
pp. 659 ◽  
Author(s):  
SP Robinson ◽  
GP Jones
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Salt Stress ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Spinacia Oleracea ◽  
Resonance Spectroscopy ◽  
Leaf Osmotic Potential ◽  
Cellular Compartments ◽  
Isolated Chloroplasts

Glycinebetaine was determined in leaves and in isolated chloroplasts of spinach (Spinacia oleracea) by nuclear magnetic resonance spectroscopy. Some leakage of glycinebetaine from the chloroplasts occurred during the isolation so the concentration in chloroplasts in vivo could be up to 1.5 times higher than that measured in isolated chloroplasts. It was demonstrated that any contamination of the chloroplast preparations by glycinebetaine originating from other cellular compartments or from broken chloroplasts would have amounted to less than 10% of the measured values. Leaf osmotic potential of salt-stressed plants was -2.09 MPa compared to -0.91 MPa in non-stressed controls. This was accompanied by a sixfold increase in glycinebetaine content in the leaf but the levels of choline and proline were not increased. In chloroplasts isolated from control leaves the calculated glycinebetaine concentration was 26 mM which was 10-fold higher than the concentration in the leaf as a whole but only contributed 7% of the osmotic potential of the chloroplast. Chloroplasts from salt-stressed plants contained up to 300 mM glycinebetaine which was 20 times the concentration in the leaf as a whole. The glycinebetaine concentration in chloroplasts from salt-stressed leaves was equivalent to an osmotic potential of -0.75 MPa and this contributed 36% of the osmotic potential of the chloroplast and 64% of the decrease in osmotic potential induced by salt stress. At least 30-40% of the total leaf glycinebetaine was localized in the chloroplast. The results demonstrate that glycinebetaine accumulates in chloroplasts to provide osmotic adjustment during salt stress and provide support for the hypothesis that glycinebetaine is a compatible cytoplasmic solute which may be preferentially located in the cytoplasm of cells.

Osmotic Adjustment: Effect of Water Stress on Carbohydrates in Leaves, Stems and Roots of Apple

1995 ◽  
Vol 22 (5) ◽  
pp. 747 ◽  
Author(s):  
Z Wang ◽  
B Quebedeaux ◽  
GW Stutte
Keyword(s):  
Water Stress ◽  
Osmotic Adjustment ◽  
Sucrose Concentration ◽  
Starch Content ◽  
Soluble Carbohydrates ◽  
Soluble Carbohydrate ◽  
Malus Domestica Borkh ◽  
Mature Leaves ◽  
Young Leaves ◽  
Response To Water

Potted apple (Malus domestica Borkh. cv. Jonathan) trees were subjected to water stress in a greenhouse. Midday leaf water potential (ΨW), osmotic potential (ΨS), soluble carbohydrates, and starch content of expanding and mature leaves, stems, and roots were measured to determine whether active osmotic adjustment occurred and if water stress affected carbohydrate metabolism. Mature leaves had the highest total soluble carbohydrate level (357 mM) and lowest Ψ (-1.85 MPa), followed by young leaves (278 mM, -1.58 MPa), stems (115 mM, -1.02 MPa), and roots (114 mM, -0.87 MPa). Sorbitol was the major component in all organs ranging from 53% of total soluble carbohydrate in young leaves to 73% in mature leaves. When ΨW decreased from -1.0 to -3.2 MPa, active osmotic adjustments of 0.3-0.4 MPa were observed in mature leaves, stems, and roots while a significantly higher adjustment of 1.0 MPa was detected in young leaves 5 days after the initiation of water stress. Sorbitol levels in leaves and stems gradually increased as ΨW decreased from -1.0 to -2.5 MPa, and then remained relatively stable or decreased slightly as ΨW decreased from -2.5 to -3.2 MPa. However, the percentage of soluble carbohydrate as sorbitol in roots decreased in response to water stress. Sucrose concentration decreased in mature leaves and stems, but increased in young leaves and roots as ΨW decreased. Starch concentrations in stems and roots also decreased as water stress developed. The sorbitol to sucrose ratios increased in mature leaves, but decreased in roots in response to water stress.

Inhibition of Flowering in Lolium temulentum L. By Water Stress: a Role for Abscisic Acid

1977 ◽  
Vol 4 (2) ◽  
pp. 225 ◽  
Author(s):  
RW King ◽  
LT Evans
Keyword(s):  
Abscisic Acid ◽  
Water Stress ◽  
Long Day ◽  
Relative Water ◽  
The One ◽  
Floral Evocation ◽  
Leaf Photosynthetic Rate ◽  
Response To Water ◽  
Aba Content ◽  
High Intensity Light

A brief, 8-h water stress during the induction of flowering in L. temulentum reduces the flowering response, the more so the greater the stress. Water stress also affected leaf photosynthetic rate, relative water content of leaves and leaf elongation. Water stress was most inhibitory to flowering when applied during the period of high-intensity light at the beginning of the one long day. The abscisic acid (ABA) content of leaves increased up to 30-fold during the imposition of water stress and fell rapidly after stress was relieved, regardless of when the stress was imposed. The greater the stress, the higher was the level of ABA in leaves and the greater was the inhibition of flowering. The ABA content of apices also rose in response to water stress, in some cases during the stress treatment but usually 8-22 h later. Flowering was inhibited when apical ABA contents were high at the end of the long day. Although water stress may influence the flowering of plants in several ways, these experiments suggest that water stress during the long day induction of L. temulentum inhibits flowering by raising the content of ABA at the shoot apex during floral evocation.

Water-stress tolerance and late-season organic solute accumulation in hybrid poplar

1989 ◽  
Vol 67 (6) ◽  
pp. 1681-1688 ◽  
Author(s):  
T. J. Tschaplinski ◽  
T. J. Blake
Keyword(s):  
Water Stress ◽  
Stress Tolerance ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Soluble Sugar ◽  
Hybrid Poplar ◽  
Turgor Loss Point ◽  
Water Stress Tolerance ◽  
Organic Solute ◽  
The Relationship

Organic solute concentrations of five hybrid poplar cultivars were compared to determine the relationship between water-stress tolerance, tissue solute concentration, and growth rate under field conditions. In the expanding foliage of the faster growing Populus deltoides Bartr. × P. balsamifera L. (Jackii 4), the saturated osmotic potential and turgor loss point osmotic potential were 0.18 MPa and 0.47 MPa lower, respectively, than in the slower growing P. deltoides × P. balsamifera (Jackii 7). The expanding foliage of Jackii 4 had higher (ca. 50%) concentrations of organic solutes, attributable mainly to salicyl alcohol, salicin, sucrose, and an unidentified compound. The coupling of high productivity and stress tolerance in Jackii 4 suggests that these may be compatible rather than competing attributes. Water-stress studies on P. deltoides Bartr. × P. nigra L. (DN 22) under greenhouse conditions demonstrated that stressed trees accumulated 4 times the soluble sugar concentrations of well-watered trees, lowering the saturated osmotic potential by 0.55 MPa and turgor loss point osmotic potential by 1.0 MPa. Leaves were the primary site of osmotic adjustment to water stress and roots showed no adjustment. The use of repeated drying cycles in planting stock may aid survival of postplanting stress in species capable of osmotic adjustment. The relationship between stress tolerance and solute concentrations in the greenhouse water-stress study paralleled that of the field study.

Mechanisms for drought resistance in early maturing cvar Flordastar peach trees

2011 ◽  
Vol 149 (5) ◽  
pp. 609-616 ◽  
Author(s):  
C. D. MELLISHO ◽  
Z. N. CRUZ ◽  
W. CONEJERO ◽  
M. F. ORTUÑO ◽  
P. RODRÍGUEZ
Keyword(s):  
Water Stress ◽  
Drought Resistance ◽  
Osmotic Adjustment ◽  
Prunus Persica ◽  
Field Studies ◽  
Passive Response ◽  
Early Maturing ◽  
Soil Water Conditions ◽  
Peach Trees ◽  
Response To Water

SUMMARYAdult early maturing peach trees (Prunus persica(L.) Batsch cvar Flordastar) grafted ontoP. persica×Prunus amygdalusGF-677 peach rootstock, were subjected to low water availability (water stress) and recovery periods for 28 and 7 days, respectively, during summer 2009. Control plants were irrigated daily at 1·3 estimated crop reference evapotranspiration (ETC) in order to obtain non-limiting soil water conditions. Active osmotic adjustment was observed at the end of the stress period. However, the magnitude of this osmotic adjustment (0·18 MPa) was not sufficient to modify the leaf water potential at turgor loss point. The observed active osmotic adjustment that maintained turgor was in contrast to other results in potted peach trees, where no osmotic adjustment was observed, and highlights the importance of field studies in which water stress is developed gradually over a prolonged period. Relative apoplastic water content (RWCa) values were high and decreased as a result of water stress. The rapid decrease in leaf conductance from the beginning of the stress period, together with the delay in stomatal reopening after rewatering, indicated that stomatal behaviour was not a simple passive response to water deficit. The results indicate that drought resistance in early maturing peach trees is based both on avoidance mechanisms, such as stomatal control and tolerance mechanisms, including active osmotic adjustment and high RWCa.

scholarly journals Changes in carbohydrates accumulation in Viguiera discolor Baker in response to water deficit

Hoehnea ◽  
2019 ◽  
Vol 46 (4) ◽  
Author(s):  
Rodrigo Fazani Esteves Sanches ◽  
Ana Paula Oliveira da Silva ◽  
Vanessa Pires da Costa ◽  
Maria Ângela Machado de Carvalho ◽  
Emerson Alves da Silva
Keyword(s):  
Water Deficit ◽  
Osmotic Adjustment ◽  
Water Status ◽  
Soluble Sugars ◽  
Water Suppression ◽  
Adaptive Responses ◽  
Close Relationship ◽  
Relative Water ◽  
Influence Of Water ◽  
Response To Water

ABSTRACT Water stress is an environmental factor that can regulate growth, limit production and lead to physiological and biochemical changes. Plants present a series of adaptive responses to drought, such as osmotic adjustment, in which carbohydrates play an important role. To evaluate the influence of water deficit on carbohydrates accumulation in V. discolor, the plants were divided into two groups: daily watering and water suppression for 14 days being re-watering after this period. Leaves and roots were collected at 0, 3, 6, 9, 12, 15 and 18 days, for ecophysiological and biochemical analyzes. Variations in carbohydrate contents in V. discolor showed a close relationship with changes in the plant water status, with higher concentrations of soluble sugars, total fructans, oligosaccharides, reducing sugars coinciding with the lower values of soil moisture and leaf water potentials and relative water content. In the tuberous roots, there is an increase in carbohydrate concentrations after re-watering. The increase of these low molecular weight carbohydrates is involved in osmotic adjustment and therefore acts to protect against dehydration.

Effects of drought stress on the water relations in Brassica species

1993 ◽  
Vol 73 (2) ◽  
pp. 525-529 ◽  
Author(s):  
Allen G. Good ◽  
James L. Maclagan
Keyword(s):  
Water Stress ◽  
Drought Stress ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Physiological Responses ◽  
Brassica Species ◽  
Leaf Osmotic Potential ◽  
Drought Conditions ◽  
Relative Water ◽  
Effects Of Drought

The physiological responses of different species of Brassica to induced drought stress were studied by analysing the relationships between relative water content, leaf water potential and leaf osmotic potential during the onset of drought stress. These data indicate that while there was a decrease in leaf osmotic potential with the onset of drought stress, this did not result from a net increase in solutes. Therefore, these genotypes of Brassica do not appear able to osmoregulate under these drought conditions. Key words: Brassica, drought, osmoregulation, water stress

Growth and yield of sorghum lines extracted from a population for differences in osmotic adjustment

1995 ◽  
Vol 46 (1) ◽  
pp. 61 ◽  
Author(s):  
T Tangpremsri ◽  
S Fukai ◽  
KS Fischer
Keyword(s):  
Water Stress ◽  
Grain Yield ◽  
Leaf Area ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Dry Matter ◽  
Grain Filling ◽  
Grain Number ◽  
Glasshouse Experiment ◽  
The Difference

From 47 S2 lines which had been extracted from a random mated population of sorghum, eight lines for a glasshouse experiment and four lines for a field experiment were divergently selected for variation in osmotic adjustment, and were grouped into two, High and Low osmotic adjustment (OA). Both the glasshouse and field experiments examined whether osmotic adjustment modified the plants' response to soil water deficit and also whether grain sink demand for assimilates, varied by removal of 50% spikelets, affected osmotic adjustment. In each experiment, there were well-watered control and water stress treatments. In both experiments, the dawn osmotic potential in the High OA group was always lower than in the Low OA group under water limiting conditions, and the difference was significant after anthesis. The difference in osmotic potential was about 0.1 MPa in the field and up to 0.25 MPa in the glasshouse. In the glasshouse experiment, removal of 50% spikelets at anthesis significantly decreased osmotic potential during grain filling, suggesting that osmotic adjustment is influenced by the availability of assimilates in the leaves. Under well-watered conditions, the two groups behaved very similarly in terms of maximum leaf area, green leaf area retention during grain filling, total dry matter production, grain yield and grain number in both experiments. Under water-limiting conditions, the High OA group produced larger maximum leaf area and had better leaf retention during grain filling. Despite similar water use, total dry matter was also significantly higher in the High OA group though the difference was small. Grain number was also greater in this group in both experiments, whereas grain yield was significantly higher in the High OA group in the field, but not in the glasshouse where severe water stress developed more rapidly. It is concluded that the adverse effect of water stress can be reduced by adopting sorghum genotypes with high osmotic adjustment. However, selection for high osmotic adjustment needs to ensure that osmotic adjustment is not solely due to small head size.

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