Root osmotic potential and length for two maize lines differing in leaf osmotic potential

2019 ◽  
Vol 33 (4) ◽  
pp. 429-444 ◽  
Author(s):  
Amber Beseli ◽  
Antonio J. Hall ◽  
Anju Manandhar ◽  
Thomas R. Sinclair
Keyword(s):  
Osmotic Potential ◽  
Leaf Osmotic Potential

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.

scholarly journals Sugar/osmoticum levels modulate differential abscisic acid-independent expression of two stress-responsive sucrose synthase genes in Arabidopsis

1999 ◽  
Vol 344 (2) ◽  
pp. 503-509 ◽  
Author(s):  
Annabelle DÉJARDIN ◽  
Lubomir N. SOKOLOV ◽  
Leszek A. KLECZKOWSKI
Keyword(s):  
Signal Transduction ◽  
Abscisic Acid ◽  
Cold Stress ◽  
Osmotic Potential ◽  
Sucrose Synthase ◽  
Cellular Response ◽  
Expression Profiles ◽  
Soluble Sugars ◽  
Leaf Osmotic Potential ◽  
Detached Leaves

Sucrose synthase (Sus) is a key enzyme of sucrose metabolism. Two Sus-encoding genes (Sus1 and Sus2) from Arabidopsis thaliana were found to be profoundly and differentially regulated in leaves exposed to environmental stresses (cold stress, drought or O2 deficiency). Transcript levels of Sus1 increased on exposure to cold and drought, whereas Sus2 mRNA was induced specifically by O2 deficiency. Both cold and drought exposures induced the accumulation of soluble sugars and caused a decrease in leaf osmotic potential, whereas O2 deficiency was characterized by a nearly complete depletion in sugars. Feeding abscisic acid (ABA) to detached leaves or subjecting Arabidopsis ABA-deficient mutants to cold stress conditions had no effect on the expression profiles of Sus1 or Sus2, whereas feeding metabolizable sugars (sucrose or glucose) or non-metabolizable osmotica [poly(ethylene glycol), sorbitol or mannitol] mimicked the effects of osmotic stress on Sus1 expression in detached leaves. By using various sucrose/mannitol solutions, we demonstrated that Sus1 was up-regulated by a decrease in leaf osmotic potential rather than an increase in sucrose concentration itself. We suggest that Sus1 expression is regulated via an ABA-independent signal transduction pathway that is related to the perception of a decrease in leaf osmotic potential during stresses. In contrast, the expression of Sus2 was independent of sugar/osmoticum effects, suggesting the involvement of a signal transduction mechanism distinct from that regulating Sus1 expression. The differential stress-responsive regulation of Sus genes in leaves might represent part of a general cellular response to the allocation of carbohydrates during acclimation processes.

Temporal water use by two maize lines differing in leaf osmotic potential

Crop Science ◽  
2020 ◽  
Vol 60 (2) ◽  
pp. 945-953 ◽  
Author(s):  
Amber L. Beseli ◽  
Avat Shekoofa ◽  
Mujahid Ali ◽  
Thomas R. Sinclair
Keyword(s):  
Water Use ◽  
Osmotic Potential ◽  
Leaf Osmotic Potential

Osmotic Adjustment in Expanding and Fully Expanded Leaves of Sunflower in Response to Water Deficits

1980 ◽  
Vol 7 (2) ◽  
pp. 181 ◽  
Author(s):  
MM Jones ◽  
NC Turner
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Similar Degree ◽  
Tissue Water ◽  
Predawn Leaf Water Potential ◽  
Leaf Osmotic Potential ◽  
Osmotic Potentials

Sunflower plants were grown in large volumes of soil and slowly water-stressed by withholding water. The tissue water relationships of leaves at various stages of stress and of leaves of equivalent well watered controls were studied by the pressure chamber technique. Plants were stressed either when leaf 17 was expanding or when it was fully expanded. When expanding leaves reached a moderate level of stress (predawn leaf water potential of -0.9 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.1 MPa and 0.2 MPa, respectively. When fully expanded leaves were stressed to a similar degree (predawn leaf water potential of - 1.1 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.2 MPa and 0.3 MPa, respectively. The development of more severe stress in the fully expanded leaves was not accompanied by any further osmotic adjustment. However, when the expanding leaves reached a predawn leaf water potential of -2.3 MPa, the values of leaf osmotic potential at full turgor and zero turgor were lower than the values for the well watered plants by 0.4 MPa and 0.6 MPa, respectively. In expanding leaves prestressed to a predawn leaf water potential of -2.3 MPa, the osmotic potential at full turgor was significantly less than the control values for at least 7 days after rewatering. Stress had no effect on the bulk modulus of elasticity. It is concluded that both expanding and fully expanded sunflower leaves show osmotic adjustment.

scholarly journals Variation among Red and Freeman Maples in Response to Drought and Flooding

HortScience ◽  
1999 ◽  
Vol 34 (4) ◽  
pp. 664-668 ◽  
Author(s):  
James A. Zwack ◽  
William R. Graves ◽  
Alden M. Townsend
Keyword(s):  
Stomatal Conductance ◽  
Osmotic Potential ◽  
Root Zone ◽  
Acer Rubrum ◽  
Weight Ratio ◽  
Control Treatment ◽  
Leaf Osmotic Potential ◽  
Leaf Surface Area ◽  
Shoot Weight ◽  
As Stress

Freeman maples (Ace×freemanii E. Murray) are marketed as stress-resistant alternatives to red maples (Acer rubrum L.). Our objective was to compare two cultivars of Freeman maple [`Jeffersred' (Autumn Blaze®) and `Indian Summer'] and five red maples [`Franksred' (Red Sunset®), `Autumn Flame', `PNI 0268' (October Glory®), `Fairview Flame', and unnamed selection 59904] for effects of flooding and water deficit on plant growth, biomass partitioning, stomatal conductance, and leaf osmotic potential. Plants grown from rooted cuttings in containers were subjected to three consecutive cycles during which root-zone water content decreased to 0.12, 0.08, and 0.02 m3·m–3, respectively. Additional plants were flooded for 75 days, while plants in a control treatment were irrigated frequently. Stomatal conductance immediately before imposing drought and after three drought cycles did not differ among genotypes and averaged 220 and 26 mmol·s–1·m–2, respectively. Differences in stomatal conductance after recovery from the first drought cycle and at the end of the second drought cycle did not vary with species. Drought reduced estimated leaf osmotic potential similarly for all genotypes; means for drought-stressed and control plants were –1.92 and –1.16 MPa, respectively. Freeman maples had a higher mean root: shoot weight ratio and a lower leaf surface area: root dryweight ratio than did red maples. Across genotypes, stomatal conductance of flooded plants initially increased by ≈20% and then fell to and remained below 50 mmol·s–1·m–2. Stomatal conductance of `Indian Summer' decreased to ≈20 mmol·s–1·m–2 after 8 days of flooding, indicating that this cultivar may be particularly sensitive to root-zone saturation.

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

Osmotic Adjustment of Sorghum and Sunflower Crops in Response to Water Deficits and Its Influence on the Water Potential at Which Stomata Close

1978 ◽  
Vol 5 (5) ◽  
pp. 597 ◽  
Author(s):  
NC Turner ◽  
JE Begg ◽  
ML Tonnet
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Stomatal Closure ◽  
Leaf Water ◽  
Water Deficits ◽  
Rate Of Increase ◽  
Leaf Osmotic Potential ◽  
Response To Water

The soil and plant water status of irrigated and unirrigated sorghum [Sorghum bicolor (L.) Moench cv. TX610] and sunflower (Helianthus annuus L. cv. Hysun 30) crops were compared on several days from the late vegetative to the early grain-filling stages of development. Additionally, the stems of plants from the irrigated and unirrigated plots of both species were cut near their base; this caused the plants to quickly dry until the stomata closed. The leaf water potential and leaf osmotic potential were measured when the stomatal resistance reached 6 s cm-� to give the water potential for stomatal closure and to provide osmotic potentials at equal turgor. Carbohydrate and potassium levels of leaves were also monitored. The mean daily minimum leaf water potentials in the irrigated sorghum and sunflower did not decrease below - 1 7 MPa and - 2.0 MPa, respectively, but decreased to - 2.1 MPa in the unirrigated sorghum and -2.6 MPa in the unirrigated sunflower. The osmotic potential at stomatal closure in the rapidly dried plants decreased with increasing leaf water deficit in both sunflower and sorghum: in both species the osmotic potential decreased approximately 0.6 MPa for each megapascal decrease in leaf water potential. The results indicate that both sorghum and sunflower adjusted osmotically in response to water deficits and that adjustment occurred at a rate of at least 0.1 MPa per day. The lowering of osmotic potential persisted less than 9 days after the relief of stress in both sunflower and sorghum. The soluble sugar concentration increased linearly in both sunflower and sorghum with osmotic adjustment: the rate of increase of soluble sugars was significantly greater in sunflower than sorghum. No changes in potassium concentration were observed during osmotic adjustment. The water potential at which the stomata closed varied from - 1.5 to -2.6 MPa in sorghum and - 1.7 to -2.7 MPa in sunflower: the water potential that induced stomatal closure decreased as the osmotic potential decreased. Stomatal closure occurred at a mean turgor of -0-5 MPa in both species: systematic error in the measurement of osmotic potential on frozen and thawed leaf tissue is considered the reason for the low turgor potentials at stomatal closure. The adaxial stomatal closed before the abaxial stomata in the sorghum and unirrigated sunflower but, since the leaf water potential initially fell rapidly and then became stable before the adaxial stomata closed, both the adaxial and abaxial stomata closed at the same leaf water potential.

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