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At least 19 recordsLinked to original sources
PubMed1992

Leaf ruminal digestion in Sorghum bicolor cultivars as influenced by water deficit.

A study was carried out on the effects of water deficit upon the specific leaf digestion of two sorghum cultivars: Novillero and Leoti Red. Using scanning electron microscopy it was established that after ruminal incubation, losses of structural integrity increased when the plants were submitted to drought conditions. This increase was marked in cv. Novillero after 48 h of digestion. For both cultivars, the phloem, mesophyll, parenchyma and epidermis were the most susceptible tissues to bacterial attack. The alterations in tissue disappearance during digestion, could partially explain the effects of water deficit upon the improvement in the nutritional quality of the two cultivars studied.

Animal Feed↗
PubMed2026

Morphological, Physiological and Transcriptomic Changes in Response to Water Deficit Stress in Brassica napus L.

Yield losses due to water-deficit (WD) conditions, especially during the reproductive stages of plant development, pose a significant threat to global canola (Brassica napus L.) production. Therefore, it is critical to investigate traits contributing to improved productivity under increased WD conditions. Here we present phenotypic, physiological and transcriptomic changes in response to WD across contrasting canola accessions exhibiting variation in drought resistance-related traits. WD significantly reduced shoot biomass, plant height, harvest index, leaf water content, photosynthetic CO2 assimilation rate, intrinsic water-use efficiency and carbon isotope discrimination. WD caused 49 to 100% of the seed yield reduction: the minimum seed yield reduction (49.66%) was observed in a doubled-haploid (DH) line, 06-5101.137, while the maximum yield reduction (94.1 to 100%) occurred in the late-flowering DH lines (06.5101.088 and 06-5101.306). Seed yield showed a positive correlation (r = 0.29 to 0.95) with shoot biomass and harvest index, leaf water content, photosynthetic CO2 assimilation rate, intrinsic water use efficiency and carbon isotope discrimination. However, it showed negative correlations with days to flower, leaf specific weight, root length, root biomass (r = -0.04 to -0.79) across water treatments. The specific leaf transcriptome analysis of the two parental lines of DH population that exhibit variation for effective water use under well-watered and water-deficient conditions revealed different categories of differentially expressed genes (DEGs): WD-responsive DEGs in BC1329 parental line (1116) and BC9102 (1205) with 754 and 853 DEGs unique to BC1329 and BC9102, respectively, WD-responsive DEGs (906), genotype-dependent DEGs (8465) and genotype × treatment interaction DEGs (353). DEG annotations revealed that the WD-treatment-affected genes were involved in stress responses and growth and development. We further located 235 DEGs within the QTL regions underlying agronomic and physiological performance. Our study provides a conceptual framework for the morphological, physiological and molecular determinants involved in water-use efficiency. Seedlings' traits with high heritability values, such as shoot biomass, leaf weight, leaf water content and Δ13C, serve as proxies for trait-based selection for improved seed yield under both water-limited and non-water-limited conditions.

Brassica napus↗
PubMed2026

Scion-based drought stress memory affects potato response to water deficit.

A scion-based stress memory signal, which was derived from drought-primed potato plants, was transmitted to new potato plants generated through vegetative reproduction. This affected potato tuber yield. Drought is one of the most significant threats to agricultural productivity worldwide. The cultivated potato (Solanum tuberosum L.) is a crop species that is sensitive to drought stress. This study investigated the impact of scion-based drought stress memory on tuber yield, physiological parameters, gene expression, and DNA methylation in the vegetative progeny of grafted plants. The tuber progeny plants remembered the drought stress signal transmitted from the drought-primed scion. Significant changes were observed in the expression of genes, primarily those related to photosynthetic metabolic pathways, as well as those associated with chromatin remodeling, DNA repair, and the plant's response to abiotic stresses. The gene expression landscape corresponded with variability in chlorophyll fluorescence parameters. In the first and the second generation of vegetatively propagated plants, scion-based memory had a positive effect on tuber yield. This was achieved by buffering the decline in yield caused by drought, as compared to plants grown under control conditions. Whole-genome bisulfite sequencing analysis revealed no correlation between changes in DNA methylation and gene expression. Drought-induced alterations in DNA methylation were erased in the second progeny generation. We propose that there is a direct causal relationship between scion-based memory of drought stress and photosynthetic efficiency, as well as potato tuber productivity.

Solanum tuberosum↗
PubMed1992

A Brassica napus transcript encoding a protein related to the Künitz protease inhibitor family accumulates upon water stress in leaves, not in seeds.

A cDNA clone encoding a Brassica napus drought-induced 22 kDa (BnD22) protein has been isolated and characterized. The BnD22 transcript accumulated in response to drought reversibly, and to other conditions of leaf water deficit such as rapid water stress or salt acclimation, but not to cold acclimation or heat shock. Exogenously applied abscisic acid induced both changes in leaf morphology similar to the drought-adaptive response and a pronounced accumulation of the BnD22 mRNA. In control and drought-adapted plants, the BnD22 transcript was expressed in an organ-specific manner: the mRNA level was highest in leaves, low in hypocotyls and undetectable in roots. Sequence analysis indicates that the BnD22 protein is related to the Künitz family of protease inhibitors. In contrast to most members of this family, and also to most polypeptides expressed in vegetative tissues upon drought, the BnD22 mRNA was absent in seeds, before or during the seed desiccation phase. The BnD22 gene represents a new class of genes which are strictly induced in vegetative tissues upon environmental stress, and its pattern of expression shows that the responses to water deficit differ, at least partially, in seeds and in leaves.

Amino Acid Sequence↗
PubMed2026

OsICL-associated metabolic reprogramming during dehydration in rice is regulated by ABA and modulated by ACC and its metabolites.

Drought coordinates hormonal, transcriptional, and metabolic reprogramming, but how abscisic acid (ABA) and 1-aminocyclopropane-1-carboxylic acid (ACC) jointly shape cereal dehydration responses remains unclear. We integrated hormone profiling, transcriptome and promoter analyses, synthetic promoter assays, and metabolite profiling in rice. ABA and ACC contents increased markedly in rice shoots under moderate soil water deficit. Combined ABA + ACC treatment showed larger absolute overlaps with dehydration-responsive genes than either ABA or ACC treatment alone in shoots; in roots, this pattern was observed for induced but not repressed genes. Promoters of dehydration- and ABA-inducible genes were enriched in ACGT-core motifs, including a CGTACG core preferentially embedded in ACGTACGT, designated the eXtended ACGT box (Xbox). Multimerised Xbox conferred transcriptional induction under soil water deficit and in response to ABA. OsICL was induced under soil water deficit and by ABA or ACC; in shoots, combined ABA + ACC treatment produced the highest mean transcript accumulation. OsICL overexpression and knockout lines showed altered organic-acid, sugar, and amino-acid profiles, particularly under soil water deficit, but several metabolites changed in the same direction in both line classes. These findings support an ABA-centred, ACC-modulated model of dehydration-responsive transcription and associate OsICL regulation with broader, condition-dependent changes in primary metabolism.

Oryza sativa↗
PubMed1975

Osmotic thirst suppression during 2,4-dinitrophenol (DNP) hyperthermiain the dog.

The effect of generalized body hyperthermia elicited by intravenous infusion of 2,4-dinitrophenol (DNP) on the reactivity of the thirst mechanism to osmotic stimuli was examined in conscious dogs. DNP increased deep body temperature by 1.53 +/- 0.18 degrees C in 18 out of 20 experiments. Impairement of thrist sensation was observed at the same time. The animals did not drink enough water to compensat for its total and evaporative loss. In cosequence water deficit developed, reaching maximum value of 2.7 plus 0.6% of body weight. The deficit was accompanied by an increase in plasma osmolarity, plasma protein concentration and hematocrit. A significant correlation between evaporative water loss and water deficit as well as between increase in deep body temperature and water deficit was found. The cellular dehydration developed in the course of DNP hyperthermia was higher by 3.3 +/- 0.6% of intracellular water (P less than 0.001) than that which was necessary to elicit drinking under conditions of normothermia. It is concluded that DNP hyperthermia changes the osmotic reactivity of the thirst mechanism so that the body fluids osmolarity is regulated at a higher level. This finding is discussed with regard to voluntary dehydration.

Animals↗
PubMed2026

Alleviation of CO2-Induced Reductions in Tomato Photosynthesis Under Deficit Irrigation by Purple Nonsulfur Photosynthetic Bacteria.

The stimulatory effect of elevated CO2 (eCO2) on photosynthesis in most C3 crops under water deficit often declines over time due to photosynthetic acclimation. An exception occurs in plants inoculated with symbiotic nitrogen-fixing bacteria. Photosynthetic bacteria (PSB), specifically anoxygenic purple nonsulfur bacteria (Rhodopseudomonas palustris in this study), a group of nitrogen-fixing bacteria, are effective in enhancing crop photosynthesis. Therefore, this study investigated the synergistic effects of PSB and eCO2 in alleviating the effects of deficit irrigation and enhancing photosynthetic capacity in tomato plants during prolonged exposure. Our results showed that photosynthetic efficiency was significantly reduced in noninoculated plants under eCO2, and this reduction was more pronounced under water deficit. Proteomic analysis revealed that in eCO2-treated plants, the downregulation of cell wall proteins increased mesophyll resistance to CO2 diffusion, while the suppression of the photosynthetic apparatus impaired electron transport capacity, ultimately reducing CO2 assimilation efficiency. In contrast, these negative effects were alleviated by PSB inoculation. PSB promoted the upregulation of proteins involved in photosynthesis under deficit irrigation, as well as proteins related to chlorophyll biosynthesis, components of photosystem I and II, and light-harvesting complex proteins. These proteins contributed to improved photosynthetic efficiency during deficit irrigation and photosynthetic acclimation. Physiological analyses further confirmed that PSB inoculation enhanced nitrogen content, electron transport capacity, chlorophyll biosynthesis, and overall photosynthetic performance under eCO2 and deficit irrigation, resulting in improved plant growth. These findings suggest that PSB inoculation is a promising strategy to sustain and enhance the CO2 fertilization effect on crop productivity under water-limited conditions.

Photosynthesis↗
PubMed1977

Time course of lithium-induced alterations in renal and endocrine function in normal and Brattleboro rats with hypothalamic diabetes insipidus.

1. A lithium chloride (1.1 g/kg) supplemented diet was given to Long Evans (LE) and Brattleboro (DI) rats to investigate its actions in the presence (LE) and absence (DI) of vasopressin. 2. During the first 24 h, Li-supplemented LE rats displayed an initial water deficit (drinking less than renal output), increased plasma antidiuretic (ADH) titres and slightly increased plasma renin activities (PRA) and plasma osmolarities. Such changes were qualitatively similar to those seen in rats fed a normal diet, but deprived of water for 24 hours. After 12 days, the Li-supplemented rats had elevated plasma ADH titres, but reduced pituitary oxytocic and antidiuretic activities. 3. The urinary losses of Na, K and Cl exceeded dietary intakes in LE rats on the introduction of the Li-supplement, and the urinary osmolarity fell by 50%. Electrolyte balances were gradually re-established, although drinking and urine production increased in parallel to reach twice the control values by day 12 of the supplement. 4. Aldosterone and corticosterone secretory rates and their peripheral plasma concentrations were unchanged both after 24 h and 28 days of the Li-supplement. 5. Li elicited no water deficit or saluresis in DI rats, and although the polyuria and polydipsia were exacerbated, urinary osmolarity did not change over the 12 day observation period. 6. Li increased Ca excretion in both rat types; after 12 days the PRA of DI but not LE animals were increased. 7. It is concluded that the overall renal actions of Li are tempered by vasopressin rather than adrenocorticosteroids.

Adrenal Cortex↗
PubMed1979

Survival with severe hypernatremia.

In a 74-year-old woman, excessive insensible water loss developed secondary to a period of hot, humid weather, associated with an underlying inability to obtain adequate water replacement. On admission to the hospital she was comatose, clinically dehydrated, and had laboratory values consistent with a water deficit of approximately 30% (9 L) of body water. Serum sodium concentration was 202 mEq/L. Serum osmolality was 430 mOsm/L. The patient remained comatose for seven days, during which time she was vigorously treated with fluids, and she gradually recovered. This case represents what we believe is a unique report in the literature of the severity of hypernatremia developing via this pathogenic mechanism and survival in an adult with this degree of disturbance of sodium and water homeostasis.

Aged↗
PubMed1976

Increased water drinking induced by sodium depletion in sheep.

Forty-eight hours of sodium depletion by acute cannulation of a parotid duct, via the buccal papilla, in the sheep, resulted in a progressive decrease in salivary secretion rate, salivary, urinary and plasma [Na] and no change in plasma [K]. In the first 24 h of Na depletion water intake was significantly increased. As normal sheep parotid saliva [Na] is higher than plasma [Na] and salivary loss over the first 24 h represented Na loss in excess of water relative to extracellular proportions, increased water intake was not osmotically induced. However, the animals did not replace their water deficit on either of the 2 days of Na depletion. This would appear to be valuable experimental model of increased water intake probably induced by hypovaolaemia, but uncomplicated concurrent osmotic stimuli, or any other factors which might result with the other commonly used experimental stimuli of thirst such as haemorrhage.

Animals↗
PubMed1979

Physiologic alterations in the horse produced by food and water deprivation during periods of high environmental temperatures.

Eight normal horses were held without access to food or water for 72 hours during a period of high environmental temperatures. During this period, the horses had an average weight loss of 51.6 kg (10.7% of body weight). Highly significant (P less than 0.001) decreases in extracellular fluid volume (18.6 L) and plasma volume (5 L) were observed during this period as compared with base-line values. Plasma protein, sodium, chloride, and osmolality progressively increased in response to the dehydration, whereas packed cell volume, plasma potassium, calcium, magnesium, and phosphate were not significantly altered. The dehydration and clinicopathologic alterations produced were similar to those observed in other species in which the principal problem was a water deficit. After the end of the experimental dehydration period, the horses replaced 62% of the weight loss during a 1-hour period with access to water only.

Animals↗
PubMed1978

A study of permanent adipsia induced by medial forebrain lesions.

Cerebral lesions involving most of the anterior wall of the ventricle, and the medial part of the septal region, induced a permanent loss of thirst in two goats. The ventral part of the lamina terminalis remained intact in one of the animals. Pronounced dehydration (10--13% loss of b.wt.) developed during periods (3--7 days) when water supplementation was omitted. Determinations of plasma arginine vasopressin in one of the animals revealed that the dehydration did not cause any significant increase in the secretion of antidiuretic hormone. However, the water deficit induced a considerable rise in plasma renin activity and tachycardia. If anything, the caroitid blood pressure became slightly elevated towards the end of 7 d dehydration periods. The lesions obviously inactivated a cerebral sensory mechanism controlling water balance. It may have been due mainly to destruction of juxtaventricular receptors in the anterior hypothalamic region, but perhaps also to a disruption of afferents from such receptors located posterior to this cerebral level.

Animals↗
PubMed2025

Water shortage reduces PHYTOCHROME INTERACTING FACTOR 4, 5 and 3 expression and shade avoidance in Arabidopsis.

In agricultural crops, forests and grasslands, water deficit often occurs in the presence of cues from neighbouring vegetation. However, most studies have addressed separately the mechanisms of plant growth responses to these two aspects of the environment. Here we show that transferring Arabidopsis thaliana seedlings to agar containing polyethylene glycol (PEG) to restrict water availability reduces hypocotyl growth responses to shade without simultaneously affecting cotyledon expansion or its response to shade. Hypocotyl growth showed significant triple interaction among water availability, shade and the presence of PHYTOCHROME INTERACTING FACTOR 4 (PIF4), PIF5 and PIF3. Water restriction diminished auxin signalling and the activity of the PIF4, PIF5, PIF3 gene promoters and their transcript levels. The responses of PIF4 expression and hypocotyl growth to PEG were reduced in mutants of its positive morning regulators CIRCADIAN CLOCK ASSOCIATED 1 (CCA1) and LATE ELONGATED HYPOCOTYL (LHY). The CCA1 and LHY gene promoters also reduced their activity in response to PEG. In addition to the changes in PIF4 levels, post-transcriptional processes also contributed to the PIF4 protein response to PEG. Collectively, these results unveil PIFs as a hub that interlinks shade and drought information to control growth.

Arabidopsis↗
PubMedDate not supplied

Expression and molecular cloning of drought-induced genes in the wild tomato Lycopersicon chilense.

Protein synthesis and translatable mRNA population changes induced during water stress were studied in leaves of a drought-resistant wild relative of tomato, Lycopersicon chilense, using one- and two-dimensional polyacrylamide gel electrophoresis. Under our experimental conditions, water deficit did not significantly affect total protein synthesis capacity. However, it induced biphasic synthesis of a new set of proteins. These newly synthesized proteins resumed to control levels upon rehydration of the plants. Certain drought-induced proteins also accumulated in leaves subjected to heat shock (39 degrees C) or exogenous abscisic acid (ABA, 1 mM) treatments. A cDNA library was constructed using poly(A)+ RNA from leaves of plants exposed to drought stress for 4 days. Differential screening of the library identified three groups of clones corresponding to drought- and ABA-induced mRNAs. Northern blot analysis showed that the genes of selected clones respond differently to the different environmental stresses. Our data clearly demonstrate that water stress alters gene expression in L. chilense plants resulting in the synthesis of new proteins, of which several respond to high temperature stress and others to an osmotic effect. These responses are in part modulated by ABA.

Abscisic Acid↗
PubMed2026

The dirigent protein MsDIR6 functions in drought tolerance and modulates reactive oxygen species scavenging and secondary metabolite biosynthesis in alfalfa.

Alfalfa (Medicago sativa L.) is a globally significant forage crop essential for ensuring global food security. However, soil water deficit leads to a substantial decline in its yield, posing a severe threat to sustainable forage production. Dirigent (DIR) proteins play important roles in lignan biosynthesis and plant stress responses. Here, we identified 52 MsDIR genes in alfalfa through a genome-wide analysis, and screened MsDIR6 as a key candidate gene associated with drought tolerance. The results of qRT-PCR showed that MsDIR6 transcription was significantly induced by drought stress in alfalfa. MsDIR6 was preferentially expressed in roots and leaves, and its protein was localized in the nucleus and plasma membrane. Heterologous expression of MsDIR6 in yeast improved tolerance to mannitol-triggered osmotic stress. Heterologous overexpression of MsDIR6 in Arabidopsis significantly increased seed germination rate, seedling survival rate, and antioxidant capacity under drought stress, while improving leaf water-holding capacity by regulating stomatal movement. In transgenic alfalfa hairy roots, MsDIR6 alleviated drought-induced growth inhibition and enhanced reactive oxygen species (ROS) scavenging mediated by the antioxidant defense system under drought stress. Transcriptomic analysis revealed that MsDIR6 activated key genes in the phenylpropanoid and flavonoid biosynthesis pathways, which are crucial for ROS scavenging during drought adaptation. Additionally, we observed elevated flavonoid and lignin contents in MsDIR6-overexpressing alfalfa. Collectively, our findings offer novel insights into alfalfa's drought tolerance mechanisms and identify MsDIR6 as a promising genetic resource for molecular breeding strategies to improve this vital forage crop.

Alfalfa↗
PubMed1992

Phase behaviour and molecular species composition of oat root plasma membrane lipids. Influence of induced dehydration tolerance.

Tolerance to dehydration induced by repeated water-deficit stress is well correlated to changes in the lipid composition of oat root cell plasma membranes. The molecular species of the two dominant phospholipids phosphatidylcholine and phosphatidylethanolamine were determined. The four major species were 16:0/18:2, 16:0/18:3, 18:2/18:2 and 18:2/18:3. In contrast to the large changes in plasma membrane lipid composition in other respects, induced tolerance resulted in very weak alterations concerning the phospholipid molecular species pattern. Only minor alterations, appearing as a decrease in the 18:3-containing lipids, occurred. Total lipids of microsomes and isolated plasma membranes of root cells were analysed by X-ray crystallography at different degrees of hydration. The lipid phase behaviour at different degrees of hydration was further confirmed by polarization microscopy. In the presence of excess water all membrane lipids adopted a reversed micellar configuration. The plasma membrane lipids from root cells with induced dehydration tolerance formed upon dehydration two coexisting lamellar structures. The importance of the phase behaviour at different degrees of hydration for the membrane properties and the relation to membrane composition is discussed.

Edible Grain↗
PubMed2026

Heterologous expression of DobHLH25 from Dendrobium officinale enhances drought tolerance in Arabidopsis.

Drought stress severely constrains the growth, yield, and accumulation of bioactive compounds in Dendrobium officinale (D. officinale), a valuable medicinal orchid, and this challenge is exacerbated under simulated wild cultivation where plants are inevitably exposed to recurring water deficits. Basic helix-loop-helix (bHLH) transcription factors are well-established regulators of plant abiotic stress responses. However, the molecular mechanisms by which bHLH transcription factors respond to drought stress in this species remain largely unknown. In this study, a bHLH transcription factor gene, DobHLH25, was cloned from D. officinale. Phylogenetic analysis revealed that DobHLH25 shares the highest sequence identity with its ortholog in Dendrobium nobile. Additionally, subcellular localization analysis indicated that DobHLH25 is targeted to the nucleus and possesses a functional transcriptional activation domain. Expression pattern analysis showed that DobHLH25 is most abundantly expressed in old leaves, and its expression in roots, stems, and leaves is induced by polyethylene glycol treatments. Heterologous expression of DobHLH25 in Arabidopsis thaliana resulted in higher seed germination rates and longer root lengths under mannitol-induced osmotic stress compared to wild-type plants. Under drought stress, DobHLH25 heterologous expression lines exhibited higher survival rates, reduced leaf water loss, lower malondialdehyde accumulation, and increased proline content. Moreover, the activities of antioxidant enzymes such as superoxide dismutase and peroxidase were significantly enhanced, and the expression levels of multiple drought-responsive genes were markedly upregulated. Collectively, these findings suggest a correlation between DobHLH25 expression and plant drought tolerance, as evidenced by reduced oxidative damage, increased osmolyte accumulation, enhanced antioxidant enzyme activities, and upregulation of drought-responsive genes. Together, these results suggest that DobHLH25 plays a positive role in drought tolerance, and provides a basis for future dissection of its regulatory network in D. officinale.

Drought Resistance↗