scholarly journals Physiological Mechanisms of Drought Resistance in Four Native Ornamental Perennials

1994 ◽  
Vol 119 (2) ◽  
pp. 299-306 ◽  
Author(s):  
Douglas S. Chapman ◽  
Robert M. Augé
Keyword(s):  
Drought Resistance ◽  
Osmotic Adjustment ◽  
Relative Water Content ◽  
Stomatal Closure ◽  
Echinacea Purpurea ◽  
The Other ◽  
Dehydration Tolerance ◽  
Drought Avoidance ◽  
Relative Water ◽  
Monarda Didyma

Understanding physiological drought resistance mechanisms in ornamentals may help growers and landscapers minimize plant water stress after wholesale production. We characterized the drought resistance of four potted, native, ornamental perennials: purple coneflower [Echinacea purpurea (L.) Moench], orange coneflower [Rudbeckia fulgida var. Sullivantii (Beadle & Boynt.) Cronq.], beebalm (Monarda didyma L.), and swamp sunflower (Helianthus angustifolius L.). We measured a) stomatal conductance of leaves of drying plants, b) lethal water potential and relative water content, and c) leaf osmotic adjustment during the lethal drying period. Maintenance of stomatal opening as leaves dry, low lethal water status values, and ability to osmotically adjust indicate relative drought tolerance, with the reverse indicating drought avoidance. Echinacea purpurea had low leaf water potential (ψL) and relative water content (RWC) at stomatal closure and low lethal ψL and RWC, results indicating high dehydration tolerance, relative to the other three species. Rudbeckia fulgida var. Sullivantii had a similar low ψL at stomatal closure and low lethal ψL and displayed relatively large osmotic adjustment. Monarda didyma had the highest ψL and RWC at stomatal closure and an intermediate lethal ψL, yet displayed a relatively large osmotic adjustment. Helianthus angustifolius became desiccated more rapidly than the other species, despite having a high ψL at stomatal closure; it had a high lethal ψL and displayed very little osmotic adjustment, results indicating relatively low dehydration tolerance. Despite differences in stomatal sensitivity, dehydration tolerance, and osmotic adjustment, all four perennials fall predominantly in the drought-avoidance category, relative to the dehydration tolerance previously reported for a wide range of plant species.

Efficient root metabolism improves drought resistance of Festuca arundinacea

2019 ◽  
Vol 61 (3) ◽  
pp. 492-504 ◽  
Author(s):  
Dawid Perlikowski ◽  
Adam Augustyniak ◽  
Aleksandra Skirycz ◽  
Izabela Pawłowicz ◽  
Katarzyna Masajada ◽  
...  
Keyword(s):  
Water Deficit ◽  
Drought Resistance ◽  
Festuca Arundinacea ◽  
Membrane Integrity ◽  
Cellular Membrane ◽  
The Other ◽  
Drought Avoidance ◽  
Relative Water ◽  
Adverse Environmental Conditions ◽  
Metabolic Performance

Abstract Festuca arundinacea is a model to work on the mechanisms of drought resistance in grasses. The crucial components of that resistance still remain not fully recognized. It was suggested that deep root system could be a crucial trait for drought avoidance strategy but the other components of root performance under water deficit have not paid much attention of scientists. In this study, two genotypes of F. arundinacea with a different ability to withstand soil water deficit were selected to perform comprehensive research, including analysis of root architecture, phytohormones, proteome, primary metabolome and lipidome under progressive stress conditions, followed by a rewatering period. The experiments were performed in tubes, thus enabling undisturbed development of root systems. We demonstrated that long roots are not sufficient to perfectly avoid drought damage in F. arundinacea and to withstand adverse environmental conditions without a disturbed cellular metabolism (with respect to leaf relative water potential and cellular membrane integrity). Furthermore, we proved that metabolic performance of roots is as crucial as its architecture under water deficit, to cope with drought stress via avoidance, tolerance and regeneration strategies. We believe that the presented studies could be a good reference for the other, more applied experiments, in closely related species.

scholarly journals Isolation, purification and characterization of an ascorbate peroxidase from celery and overexpression of the AgAPX1 gene enhanced ascorbate content and drought tolerance in Arabidopsis

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Jie-Xia Liu ◽  
Kai Feng ◽  
Ao-Qi Duan ◽  
Hui Li ◽  
Qing-Qing Yang ◽  
...  
Keyword(s):  
Drought Stress ◽  
Ascorbate Peroxidase ◽  
Drought Resistance ◽  
Stomatal Closure ◽  
High Survival ◽  
Gene Encoding ◽  
Sds Page ◽  
Relative Water ◽  
New Evidence

Abstract Background Celery is a widely cultivated vegetable abundant in ascorbate (AsA), a natural plant antioxidant capable of scavenging free radicals generated by abiotic stress in plants. Ascorbate peroxidase (APX) is a plant antioxidant enzyme that is important in the synthesis of AsA and scavenging of excess hydrogen peroxide. However, the characteristics and functions of APX in celery remain unclear to date. Results In this study, a gene encoding APX was cloned from celery and named AgAPX1. The transcription level of the AgAPX1 gene was significantly upregulated under drought stress. AgAPX1 was expressed in Escherichia coli BL21 (DE3) and purified. The predicted molecular mass of rAgAPX1 was 33.16 kDa, which was verified by SDS-PAGE assay. The optimum pH and temperature for rAgAPX1 were 7.0 and 55 °C, respectively. Transgenic Arabidopsis hosting the AgAPX1 gene showed elevated AsA content, antioxidant capacity and drought resistance. Less decrease in net photosynthetic rate, chlorophyll content, and relative water content contributed to the high survival rate of transgenic Arabidopsis lines after drought. Conclusions The characteristics of APX in celery were different from that in other species. The enhanced drought resistance of overexpressing AgAPX1 in Arabidopsis may be achieved by increasing the accumulation of AsA, enhancing the activities of various antioxidant enzymes, and promoting stomatal closure. Our work provides new evidence to understand APX and its response mechanisms to drought stress in celery.

Studies on the Status of Unburnt Eucalyptus Woodland at Ocean Grove, Victoria. V. The Interactive Effects of Droughting and Shading on Seedlings Under Competition.

1979 ◽  
Vol 27 (3) ◽  
pp. 285 ◽  
Author(s):  
JR Withers
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Drought Resistance ◽  
Relative Water Content ◽  
Height Growth ◽  
Interactive Effects ◽  
Wide Range ◽  
Relative Water ◽  
Pre Treatment ◽  
Grass Sward

Casuarina littoralis seedlings are inherently more drought-resistant than Eucalyptus ovata seedlings over a wide range of environmental conditions. Moderate shade pre-treatment (30% of full daylight) decreased the drought resistance of seedlings of E. ovata, Acacia pycnantha and C. stricta but not that of C. littoralis seedlings. Deep shade pre-treatment (8 % of full daylight) decreased the drought resistance of all species and was associated with decreased rootlshoot ratios. Both shaded and non-shaded C. littoralis seedlings closed stomata at higher relative water contents (about 80% and 88 % respectively) than did E. ovata seedlings (about 36 % and 63 % respectively). Shading decreased the relative water content at which E. ovata closed stomata and reduced the relative decrease in water potential which occurred with unit decreases in relative water content. When E. ovata and C. littoralis seedlings were grown in competition, the larger E. ovata dominated the drought response of plants under both high and low light conditions. E. ovata rapidly depleted moisture supplies thereby subjecting C. littoralis to greater stress and earlier death than it experienced in monoculture. C. littoralis seedlings grown and droughted in competition with E. ovata exhibited smaIIer decreases in water potential per unit decrease in relative water content than seedlings grown in monoculture. The height growth of E. ovata grown in monoculture and in competition with C. littoralis was reduced for at least 10-15 weeks after the wilting treatment, but height growth of C. littoralis was not affected. Eucalypts wilted at higher water potentials (-4.3 MPa) than did C. littoralis seedlings (- 6.3 MPa). It is suggested that the replacement of E. ovata by C. littoralis at Ocean Grove, Vic. may be partly due to the differential effects of shading on the drought resistance of seedlings which become established in the grass sward of canopy gaps.

Differential drought resistance strategies of co-existing woodland species enduring the long rainless Eastern Mediterranean summer

2019 ◽  
Vol 40 (3) ◽  
pp. 305-320 ◽  
Author(s):  
Päivi J Väänänen ◽  
Yagil Osem ◽  
Shabtai Cohen ◽  
José M Grünzweig
Keyword(s):  
Drought Resistance ◽  
Tree Mortality ◽  
Eastern Mediterranean ◽  
Stomatal Closure ◽  
Woody Species ◽  
The Other ◽  
Severe Drought ◽  
Resistance Strategies ◽  
Safety Margins ◽  
Species Specific

Abstract In anticipation of a drier climate and to project future changes in forest dynamics, it is imperative to understand species-specific differences in drought resistance. The objectives of this study were to form a comprehensive understanding of the drought resistance strategies adopted by Eastern Mediterranean woodland species, and to elaborate specific ecophysiological traits that can explain the observed variation in survival among these species. We examined leaf water potential (𝛹), gas exchange and stem hydraulics during 2–3 years in mature individuals of the key woody species Phillyrea latifolia L., Pistacia lentiscus L. and Quercus calliprinos Webb that co-exist in a dry woodland experiencing ~ 6 rainless summer months. As compared with the other two similarly functioning species, Phillyrea displayed considerably lower 𝛹 (minimum 𝛹 of −8.7 MPa in Phillyrea vs −4.2 MPa in Pistacia and Quercus), lower 𝛹 at stomatal closure and lower leaf turgor loss point (𝛹TLP ), but reduced hydraulic vulnerability and wider safety margins. Notably, Phillyrea allowed 𝛹 to drop below 𝛹TLP under severe drought, whereas the other two species maintained positive turgor. These results indicate that Phillyrea adopted a more anisohydric drought resistance strategy, while Pistacia and Quercus exhibited a more isohydric strategy and probably relied on deeper water reserves. Unlike the two relatively isohydric species, Phillyrea reached complete stomatal closure at the end of the dry summer. Despite assessing a large number of physiological traits, none of them could be directly related to tree mortality. Higher mortality was observed for Quercus than for the other two species, which may result from higher water consumption due to its 2.5–10 times larger crown volume. The observed patterns suggest that similar levels of drought resistance in terms of survival can be achieved via different drought resistance strategies. Conversely, similar resistance strategies in terms of isohydricity can lead to different levels of vulnerability to extreme drought.

Increased drought resistance of black locust seedlings via pretreatment of seeds with paclobutrazol

1993 ◽  
Vol 23 (12) ◽  
pp. 2548-2551 ◽  
Author(s):  
Shen Hui-Juan ◽  
Zeng Bin
Keyword(s):  
Osmotic Stress ◽  
Water Content ◽  
Drought Resistance ◽  
Electrolyte Leakage ◽  
Relative Water Content ◽  
Black Locust ◽  
Cellular Stress ◽  
Relative Water

The drought resistance of black locust (Robiniapseudoacacia L.) seedlings was increased by pretreatment of seeds with 250 ppm paclobutrazol. Treated seeds produced seedlings with thick roots and higher root/shoot ratios. During osmotic stress, treated plants displayed greater relative water content, lower electrolyte leakage, and fewer symptoms of wilt when compared with untreated black locust seedlings. Paclobutrazol-treated seedlings accumulated more proline than untreated seedlings in response to drought. However, osmotically induced accumulation of putrescine, a possible marker of cellular stress, was reduced in the treated plants.

scholarly journals DIVERSE STRATEGIES OF RHODODENDRON (Rhododendron sp.) GENOTYPES IN THE WATER SHORTAGE MANAGEMENT

2020 ◽  
Vol 19 (3) ◽  
pp. 159-165
Author(s):  
Peter Ferus ◽  
Dominika Bošiaková ◽  
Jana Konôpková ◽  
Peter Hoťka
Keyword(s):  
Climate Change ◽  
Drought Resistance ◽  
Water Shortage ◽  
Proline Accumulation ◽  
The Other ◽  
Summer Drought ◽  
Free Proline ◽  
Resistance Strategies ◽  
Relative Water ◽  
Leaf Relative Water Content

Rhododendrons in numerous gardens in Central Europe are frequently endangered by adverse summer drought periods associated with the climate change. Therefore, in this work drought-resistance strategies in recent genotypes of these highly aesthetic shrubs were investigated. Dehydrated Rhododendron groenlandicum ‘Helma’, R. obtusum ‘Michiko’ and R. hybridum ‘Polarnacht’ showed high initial stomatal conductances (gS), after few days steeply falling to the stable minimum at ca. 20, 85 and 70% leaf relative water content (RWC), respectively. Except of ‘Polarnacht’, they had relatively large specific leaf area and ‘Michiko’ also free proline accumulation. On the other hand, R. repens ‘Scarlet Wonder’ and R. hybridum ‘Red Jack’ started with half gS values, continuously declining 1.5–2 fold longer compared to the first group of genotypes (RWC of ca. 60 and 75%, respectively). Both produced relatively thick leaves but did not show any osmotic adjustment. Among observed drought-resistance strategies, lower and longer period active transpiration with stomata sensitive to the water loss, as found in R. repens ‘Scarlet Wonder’ and R. × hybridum ‘Red Jack’, were accepted as the most effective for drought-affected rhododendron plantations.

Genotypic variation for drought stress response traits in soybean. I. Variation in soybean and wild Glycine spp. for epidermal conductance, osmotic potential, and relative water content

2008 ◽  
Vol 59 (7) ◽  
pp. 656 ◽  
Author(s):  
A. T. James ◽  
R. J. Lawn ◽  
M. Cooper
Keyword(s):  
Water Content ◽  
Wild Species ◽  
Osmotic Potential ◽  
Relative Water Content ◽  
Stomatal Closure ◽  
Genotypic Variation ◽  
Soil Water Potential ◽  
Genotypic Differences ◽  
Relative Water ◽  
Soybean Genotypes

Studies were undertaken to assess genotypic variation in soybean and related wild species for traits with putative effects on leaf turgor maintenance in droughted plants. Traits of interest were (i) epidermal conductance (ge) which influences the rate of water loss from stressed leaves after stomatal closure; (ii) osmotic adjustment (OA) as indicated by tissue osmotic potential (π), which potentially affects the capacity to withdraw water at low soil water potential; and (iii) relative water content (RWC) at incipient leaf death (critical relative water content, RWCC), which is a measure of the dehydration tolerance of leaf tissue. The germplasm comprised a diverse set of 58 soybean genotypes, 2 genotypes of the annual wild species G. soja and 9 genotypes representing 6 perennial wild Glycine spp. indigenous/endemic to Australia. Seedling plants were grown in soil-filled beds in the glasshouse and exposed to terminal water deficit stress from the second trifoliolate leaflet stage (21 days after sowing). Measurements were made on well watered plants, moderately stressed plants, and at incipient plant death, in 2 separate studies. In both studies, there were significant genotypic differences in all 3 traits in the stressed plants. However, across the 3 sample times, ge decreased and the absolute magnitude of π increased, indicating that the expression of these traits changed as the plants acclimated to the stress. RWC was therefore used as a covariate to adjust the genotypic values of π and ge in order to facilitate comparison at a consistent plant water status of 70% RWC. There was statistically significant genotypic variation for the adjusted values, ge70 and π70, in both studies, and genotypic correlations between the 2 studies were significant (P < 0.05) and positive for all 3 traits: ge70 (r = 0.48), π70 (r = 0.50), and RWCC (r = 0.53). Among the soybean genotypes, there was at least a 2-fold range in ge70, a 0.7 MPa range in π70, and a 12 percentage point range in RWCC. Some of the perennial wild genotypes exhibited lower values of ge and RWCC and greater OA than soybean and G. soja, consistent with adaptation to drier environments. While the repeatability of measurement between experiments was variable among genotypes, the studies confirmed the existence of genotypic differences for ge, OA, and RWCC in cultivated soybean, with a wider range among the wild germplasm.

scholarly journals Osmotic and Turgor Adjustment in Rosa Foliage Drought-stressed under Varying Irradiance

1990 ◽  
Vol 115 (4) ◽  
pp. 661-667 ◽  
Author(s):  
Robert M. Augé ◽  
Ann J.W. Stodola ◽  
Brian D. Pennell
Keyword(s):  
Soil Moisture ◽  
Elastic Modulus ◽  
Water Stress ◽  
Relative Water Content ◽  
The Other ◽  
Ambient Light ◽  
Moisture Treatment ◽  
Relative Water ◽  
Osmotic Potentials ◽  
Water Contents

The influence of irradiance and drought on osmotic and turgor adjustment was examined in leaves of rose (Rosa hybrida L. `Samantha'). Plants cultured under full ambient light in the greenhouse were placed in shade chambers and, after 2 weeks of acclimation, exposed to drought for 21 days. Treatments consisted of a water stress factor (well-watered and drought-stressed) and an irradiance factor (100%, 70%, and 30% of ambient irradiance). Pressure-volume analyses of leaves indicated that osmotic potentials at full turgor were decreased 0.42, 0.36, and 0.23 MPa by drought in the 100%, 70%, and 30% irradiance treatments, respectively. Plants stressed under 100% and 70% irradiance exhibited similar osmotic adjustments. Plants under 30% irradiance had higher osmotic potentials at full turgor under well-watered conditions than plants in the other two irradiance treatments and showed only 55% as much adjustment to drought. In each irradiance treatment, drought induced an increase in elastic modulus and a decrease in relative water content at zero turgor. Turgor pressures were higher across a range of relative water contents in plants in the two higher irradiance treatments under both soil moisture treatments. Turgor also was higher at any particular water potential at 100% and 70% irradiance than 30% irradiance, within each soil moisture treatment. Heavy, but not mild, shading inhibited osmotic and turgor adjustments in leaves during drought.

scholarly journals Use of physiological and biochemical indicators to identify apple varieties resistant to drought

2020 ◽  
Vol 25 ◽  
pp. 02017
Author(s):  
Galina Kiseleva ◽  
Natalia Nenko ◽  
Alla Karavaeva ◽  
Tatiana Shalyakho
Keyword(s):  
Ascorbic Acid ◽  
Water Content ◽  
Drought Resistance ◽  
Relative Water Content ◽  
Fruit Crops ◽  
Apple Varieties ◽  
The World ◽  
Relative Water ◽  
The Impact ◽  
Physiological And Biochemical

As a result of global climate change in the arid regions of the world, a decrease in the adaptability of fruit crops to drought has been noted. This explains the interest of researchers in the issues of increasing the drought resistance of fruit crops in various ways, one of which is the creation of resistant varieties as a result of selection. The use of physiological and biochemical parameters in the breeding process as diagnostic criteria for drought resistance and the identification of highly adaptive varieties of fruit crops is relevant all over the world. The objects of study are apple varieties of various ecological and geographical origins: Idared, Erli Mac, Dayton (USA), Prikubanskoe, Rassvet, Fortuna (Russia). Physiological parameters: the relative water content, the total content of chlorophylls (a + b), carotenoids, ascorbic acid in the leaves of the studied apple varieties were determined during periods before drought and during drought. Differences in the response of varieties to the impact of drought were revealed. It was found that apple varieties of local selection Prikubanskoye, Fortuna and American variety Idared have a greater ability to adapt to changing environmental conditions in comparison with other studied varieties. The revealed adaptive features during drought (retention of a high relative water content, stability of the pigment system, a low ratio of the total chlorophyll to carotenoids, an increased content of ascorbic acid) make it possible to use them in breeding as donors of drought resistance traits. The data of physiological and biochemical studies, obtained in the unique natural and climatic conditions of the North Caucasus region of Russia, complement fundamental research on the physiological foundations of apple tree adaptation to drought.

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