scholarly journals Dynamic changes in ABA content in water-stressed Populus nigra: effects on carbon fixation and soluble carbohydrates

2019 ◽  
Vol 124 (4) ◽  
pp. 627-643 ◽  
Author(s):  
Cecilia Brunetti ◽  
Antonella Gori ◽  
Giovanni Marino ◽  
Paolo Latini ◽  
Anatoly P Sobolev ◽  
...  

AbstractBackground and AimsHydraulic and chemical signals operate in tandem to regulate systemic plant responses to drought. Transport of abscisic acid (ABA) through the xylem and phloem from the root to shoot has been suggested to serve as the main signal of water deficit. There is evidence that ABA and its ABA-glycosyl-ester (ABA-GE) are also formed in leaves and stems through the chloroplastic 2-C-methylerythritol-5-phosphate (MEP) pathway. This study aimed to evaluate how hormonal and hydraulic signals contribute to optimize stomatal (gs), mesophyll (gm) and leaf hydraulic (Kleaf) conductance under well-watered and water-stressed conditions in Populus nigra (black poplar) plants. In addition, we assessed possible relationships between ABA and soluble carbohydrates within the leaf and stem.MethodsPlants were subjected to three water treatments: well-watered (WW), moderate stress (WS1) and severe stress (WS2). This experimental set-up enabled a time-course analysis of the response to water deficit at the physiological [leaf gas exchange, plant water relations, (Kleaf)], biochemical (ABA and its metabolite/catabolite quantification in xylem sap, leaves, wood, bark and roots) and molecular (gene expression of ABA biosynthesis) levels.Key ResultsOur results showed strong coordination between gs, gm and Kleaf under water stress, which reduced transpiration and increased intrinsic water use efficiency (WUEint). Analysis of gene expression of 9-cis-epoxycarotenoid dioxygenase (NCED) and ABA content in different tissues showed a general up-regulation of the biosynthesis of this hormone and its finely-tuned catabolism in response to water stress. Significant linear relationships were found between soluble carbohydrates and ABA contents in both leaves and stems, suggesting a putative function for this hormone in carbohydrate mobilization under severe water stress.ConclusionsThis study demonstrates the tight regulation of the photosynthetic machinery by levels of ABA in different plants organs on a daily basis in both well-watered and water stress conditions to optimize WUEint and coordinate whole plant acclimation responses to drought.

Agronomy ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 45
Author(s):  
Fernando Alferez ◽  
Jian Wu ◽  
James H. Graham

The effects of drought stress on phospholipase D (PLD) gene expression and enzymatic activity were investigated in ‘Pineapple’ sweet orange. PLDs are tissue-specific, with overlapping functions, and in response to stress they may interact with ABA signaling. Tissue specificity for expression of PLDs and their regulation are unknown in citrus. To assess PLD response to water stress and gene expression/regulation in citrus, we subjected potted seedlings to increasing levels of soil drought. Evapotranspirational demand (ET) was estimated by measuring weight loss in pots, and water stress was further assessed by measuring ABA content. Three treatments were performed over a 3-week period: (a) Control treatment without drought stress (100% of daily ET); (b) mild water stress (50% ET); and (c) severe water stress (0% ET). ABA content increased during drought stress in both roots and leaves, being higher in leaves than in roots by the end of the experiment for any stress condition assayed. PLD enzymatic activity was monitored and expression of five PLD genes was studied. PLD activity increased linearly over time in response to increased soil drought and was around three times higher in roots than in leaves. PLD activation occurred initially in roots and then in leaves. PLD gene expression in response to stress soil drought differed between roots and leaves. These results show the potential of PLD as a suitable indicator of stress severity in citrus.


2008 ◽  
Vol 28 (3) ◽  
pp. 125-134 ◽  
Author(s):  
Guidong Yue ◽  
Yunlong Zhuang ◽  
Zhaoxia Li ◽  
Li Sun ◽  
Juren Zhang

The whole-genomic gene-expression changes of maize (Zea mays L.) plants in response to water-deficit stress at the heading stage have not been previously studied. The present work utilized a maize oligonucleotide array (‘57K’, ~57000 sequences; http://www.maizearray.org/) representing more than 30000 unique genes, to profile transcriptome changes in maize leaves subjected to 1d (day) and 7d water-deficit stress. After 1d and 7d water-stress treatment, 195 and 1008 differential genes were identified respectively. One-third of 1d-water-stress-induced genes had known or putative functions in various cellular signalling pathways, indicating that signal-transduction-related genes play important roles in the early responses of maize leaves to water stress. The 7d-stress-regulated genes were involved in a broad range of cellular and biochemical activities. The most notable genes may function in compatible osmolyte metabolism, particularly in proline, sucrose, trehalose and raffinose metabolism in the leaves. The present study provided a valuable starting point for further elucidation of molecular mechanisms in the drought tolerance of maize plants.


1995 ◽  
Vol 22 (5) ◽  
pp. 747 ◽  
Author(s):  
Z Wang ◽  
B Quebedeaux ◽  
GW Stutte

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.


1977 ◽  
Vol 4 (2) ◽  
pp. 225 ◽  
Author(s):  
RW King ◽  
LT Evans

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.


2014 ◽  
Vol 68 (1) ◽  
pp. 65-75
Author(s):  
Soleiman Mohammadi ◽  
Reza Kas Nazani ◽  
Ayda Hosseinzadeh Mahootchi ◽  
Keiwan Ftohi

ABSTRACT In order to evaluate promising lines in terms of grain yield and water-soluble carbohydrates remobiliza-tion, an experiment with fifteen promising lines and two checks was carried out under full irrigation and terminal water stress conditions at Miyandoab Agricultural Research and Natural Resources Station. Mobilized dry matter content and remobilization percentage from shoot to grain under water deficit (177mg)(11.2%) were greater than those under well watering condition. The lowest (110 mg) and the highest (260mg) mobilized dry matter to grain were obtained for C-79-18 and C-83-15lines, respectively. Water deficit reduced grain yield of barley genotypes by 200-1600 kg/ha, and mean grain yield reduction was 800 kg/ha. Line 14 with 5.880and 5.300t/ha grain yield in favorable and water stress conditions was superior to the other lines. Under water deficit condition, line 14 had greater grain yieldby20% and 38% than the Bahman and Makouee cultivars, respectively. The results showed that greater grain yield in tolerant lines under water deficit was due to remobilization of unstructured carbohydrates from shoot to grain. Thus, it seems that selection of lines with higher translocated dry matter and contribution of pre-anthesis assimilate in grain filling under water stress, the suitable way for achieving genotypes with high grain yield under water stress condition.


Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1149
Author(s):  
Bilal Ahmed ◽  
Mohammad Shahid ◽  
Asad Syed ◽  
Vishnu D. Rajput ◽  
Abdallah M. Elgorban ◽  
...  

Drought or water stress is a limiting factor that hampers the growth and yield of edible crops. Drought-tolerant plant growth-promoting rhizobacteria (PGPR) can mitigate water stress in crops by synthesizing multiple bioactive molecules. Here, strain PAB19 recovered from rhizospheric soil was biochemically and molecularly characterized, and identified as Enterobacter sp./Leclercia adecarboxylata (MT672579.1). Strain PAB19 tolerated an exceptionally high level of drought (18% PEG-6000) and produced indole-3-acetic acid (176.2 ± 5.6 µg mL−1), ACC deaminase (56.6 ± 5.0 µg mL−1), salicylic acid (42.5 ± 3.0 µg mL−1), 2,3-dihydroxy benzoic acid (DHBA) (44.3 ± 2.3 µg mL−1), exopolysaccharide (204 ± 14.7 µg mL−1), alginate (82.3 ± 6.5 µg mL−1), and solubilized tricalcium phosphate (98.3 ± 3.5 µg mL−1), in the presence of 15% polyethylene glycol. Furthermore, strain PAB19 alleviated water stress and significantly (p ≤ 0.05) improved the overall growth and biochemical attributes of Vigna radiata (L.) R. Wilczek. For instance, at 2% PEG stress, PAB19 inoculation maximally increased germination, root dry biomass, leaf carotenoid content, nodule biomass, leghaemoglobin (LHb) content, leaf water potential (ΨL), membrane stability index (MSI), and pod yield by 10%, 7%, 14%, 38%, 9%, 17%, 11%, and 11%, respectively, over un-inoculated plants. Additionally, PAB19 inoculation reduced two stressor metabolites, proline and malondialdehyde, and antioxidant enzymes (POD, SOD, CAT, and GR) levels in V. radiata foliage in water stress conditions. Following inoculation of strain PAB19 with 15% PEG in soil, stomatal conductance, intercellular CO2 concentration, transpiration rate, water vapor deficit, intrinsic water use efficiency, and photosynthetic rate were significantly improved by 12%, 8%, 42%, 10%, 9% and 16%, respectively. Rhizospheric CFU counts of PAB19 were 2.33 and 2.11 log CFU g−1 after treatment with 15% PEG solution and 8.46 and 6.67 log CFU g−1 for untreated controls at 40 and 80 DAS, respectively. Conclusively, this study suggests the potential of Enterobacter sp./L. adecarboxylata PAB19 to alleviate water stress by improving the biological and biochemical features and of V. radiata under water-deficit conditions.


2017 ◽  
Vol 30 (2) ◽  
pp. 447-457 ◽  
Author(s):  
ALEXANDRE REUBER ALMEIDA DA SILVA ◽  
FRANCISCO MARCUS LIMA BEZERRA ◽  
CLAUDIVAN FEITOSA DE LACERDA ◽  
CARLOS HENRIQUE CARVALHO DE SOUSA ◽  
MARLOS ALVES BEZERRA

ABSTRACT The objective of this study was to characterize the physiological acclimation responses of young plants of the dwarf coconut cultivar Jiqui Green‘ associated with tolerance to conditions of multiple abiotic stresses (drought and soil salinity), acting either independently or in combination. The study was conducted under controlled conditions and evaluated the following parameters: leaf gas exchange, quantum yield of chlorophyll a fluorescence, and relative contents of total chlorophyll (SPAD index). The experiment was conducted under a randomized block experimental design, in a split plot arrangement. In the plots, plants were exposed to different levels of water stress, by imposing potential crop evapotranspiration replacement levels equivalent to 100%, 80%, 60%, 40%, and 20%, whereas in subplots, plants were exposed to different levels of soil salinity (1.72, 6.25, 25.80, and 40.70 dS m-1). Physiological mechanisms were effectively limited when water deficit and salinity acted separately and/or together. Compared with soil salinity, water stress was more effective in reducing the measured physiological parameters. The magnitudes of the responses of plants to water supply and salinity depended on the intensity of stress and evaluation period. The physiological acclimation responses of plants were mainly related to stomatal regulation. The coconut tree has a number of physiological adjustment mechanisms that give the species partial tolerance to drought stress and/or salt, thereby enabling it to revegetate salinated areas, provided that its water requirements are at least partially met.


2021 ◽  
pp. 110747
Author(s):  
Mahvash Afshari ◽  
Mehdi Rahimmalek ◽  
Mohammad R. Sabzalian ◽  
Monika Bielecka ◽  
Adam Matkowski ◽  
...  

2013 ◽  
Vol 161 ◽  
pp. 81-87 ◽  
Author(s):  
Lidong Zhang ◽  
Liuxia Zhang ◽  
Jianlei Sun ◽  
Zhenxian Zhang ◽  
Huazhong Ren ◽  
...  

Plants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1615
Author(s):  
Zikria Zafar ◽  
Fahad Rasheed ◽  
Ahsan Ul Haq ◽  
Faridah Hanum Ibrahim ◽  
Shazia Afzal ◽  
...  

Mitigating climate change requires the identification of tree species that can tolerate water stress with fewer negative impacts on plant productivity. Therefore, the study aimed to evaluate the water stress tolerance of young saplings of C. erectus and M. alba under three soil water deficit treatments (control, CK, 90% field capacity, FC, medium stress MS, 60% FC and high stress, HS, 30% FC) under controlled conditions. Results showed that leaf and stem dry weight decreased significantly in both species under MS and HS. However, root dry weight and root/shoot ratio increased, and total dry weight remained similar to CK under MS in C. erectus saplings. Stomatal conductance, CO2 assimilation rate decreased, and intrinsic water use efficiency increased significantly in both species under MS and HS treatments. The concentration of hydrogen peroxide, superoxide radical, malondialdehyde and electrolyte leakage increased in both the species under soil water deficit but was highest in M. alba. The concentration of antioxidative enzymes like superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase also increased in both species under MS and HS but was highest in C. erectus. Therefore, results suggest that C. erectus saplings depicted a better tolerance to MS due to an effective antioxidative enzyme system.


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