Conditions Of Water Deprivation Research Articles

P171 WATER DEPRIVATION REDUCES WATER INTAKE AND INCREASES SUCROSE INTAKE IN SPONTANEOUSLY HYPERTENSIVE RATS: POSSIBLE MECHANISMS

Background and Objective: Water deprivation (WD), a common situation in wild and human lives, can induce an increase in sucrose palatability in SHR. However, it is not known if SHR also has an increase in sucrose intake after WD and if this intake is related to energy intake, as WD reduces food intake, or to the change in sucrose palatability. Methods: Adult (∼12 weeks) male Holtzman (normotensive, NT) or SHR rats (n = 20/strain) were used. In protocol 1, all rats were first subjected to 24-h WD. Food consumption was measured during WD and was used for the non-water deprived (ND)/food restricted (FD) group to equal energy consumption. Three days after the WD, rats were randomly assigned to the 24-hour WD or the ND/FR group. In protocol 2, animals were implanted with an intraoral cannula and were randomly assigned as above. Results: In the WD condition, water intake was greater in NT (15.9 ± 1.1, vs. SHR: 8.6 ± 0.2 mL/120 min, p < 0.05), whereas sucrose intake was greater in SHR (8.8 ± 0.7, vs. NT: 2.1 ± 1 mL/120 min, p< 0.05). In the ND/FR condition, water intake was very low in both strains, however, SHR had a higher sucrose intake compared to NT (11.5 ± 2.0, vs. NT: 3.3 ± 1.8 mL/120 min; p < 0.05). In NT rats, in the WD condition, there was a decrease in sucrose palatability compared to the ND/FR condition, whereas in SHR palatability was similar in the WD or ND/FR condition. SHR have a greater mean arterial pressure than NT (167 ± 3 vs, NT: 105 ± 2 mmHg). Conclusions: Our results suggest that SHR favours energy intake during WD, since during ND/FR they drank equivalent amount of sucrose. This suggestion is supported by the absence of a greater palatability to sucrose in SHR when food is restricted. Support: CAPES PrINT, FAPESP, CNPq

Histamine H3 receptor activation in the insular cortex during taste memory conditioning decreases appetitive response but accelerates aversive memory extinction under an ad libitum liquid regimen

Conditioned taste aversion (CTA) is a robust associative learning; liquid deprivation during this conditioning allows researchers to obtain readable measures of associative learning. Recent research suggests that thirst could be a crucial motivator that modulates conditioning and memory extinction processes, highlighting the importance of the body’s internal state during learning. Furthermore, the histaminergic system is one of the major modulatory systems controlling several behavioral and neurobiological functions, such as feeding, water intake, and nociception. Therefore, this research aimed to assess the effect of H3 histaminergic receptor activation in the insular cortex (IC) during CTA. For this, we conditioned adult male Wistar rats under two regimens: water deprivation and water ad libitum. A classical CTA protocol was used for water deprivation. Before CTA acquisition, 10 μM R-α-methylhistamine (RAMH), an H3 receptor agonist, was injected into the IC. Results showed that RAMH injections decreased CTA in water-deprived rats without affecting the significant aversion conditioning in rats that were given water ad libitum. Moreover, RAMH accelerated the process of aversive memory extinction under ad libitum water conditions. According to our findings, the degree of liquid satiety differentially affected taste-aversive memory formation, and H3 histamine receptors were more involved under water deprivation conditions during acquisition. However, these receptors modulated the strength of aversive conditioning by altering the rate of aversive memory extinction in the absence of deprivation. In conclusion, histaminergic activity in the IC may influence taste memory dynamics through different mechanisms depending on the degree of liquid satiety or deprivation during conditioning.

Drought heightens severity of diseases caused by Botryosphaeria dothidea and Cryptostroma corticale and needs to be factored in to properly assess pathogenicity or fulfill Koch’s postulates

AbstractClimate change is driving the emergence of novel tree diseases at the global scale, requiring new approaches for the formal confirmation of the pathogenicity of novel pathogens on novel hosts. At the same time, predictive models need to account for the possible effect of environmental changes and of abiotic stressors on disease severity for all diseases. By wound-inoculating Botryosphaeria dothidea on potted California coast live oaks and Cryptostroma corticale on potted silver maples, simultaneously in well-watered and in water-deprived conditions, I show that drought conditions increase the severity of disease symptoms. I also show that, by including a water-stressed treatment, I can formally prove pathogenicity and fulfill Koch’s postulates for putative pathogens that could not be confirmed in the absence of the stressor. Additionally, I show that the inclusion of data obtained in water stress conditions increases the differentiation between symptoms caused by fungal infection vs. symptoms caused by wound trauma, thus reducing the possible effect of outliers, a significant problem affecting many trials for fulfilling Koch’s postulates conducted with a limited number of replicates. The availability of comparable datasets in the presence and the absence of an abiotic stressor allows for the calculation of an Environmental Disease Component Index. Positive values of the index indicate a significant role of environmental change in disease progression and identify those pathogens that must be modeled factoring in climatic stressors. I suggest that this index may be extremely valuable for identifying pathogens likely to become emergent as climate changes.

Locomotor Activity of Adult Olive Fruit Flies Recorded under Conditions of Food or Water Deprivation

The olive fruit fly, known as Bactrocera oleae (Rossi) (Diptera: Tephritidae), is causing substantial economic losses in olive crops worldwide. Studying the activity patterns of the insect may expand our knowledge to eventually adopt more sustainable and effective pest control approaches. In the present study, we investigated the impact of food and water deprivation on the mobility of olive fruit flies using a modified version of the LAM25 system (locomotor activity monitor)—Trikinetics, an automated locomotor activity electronic device. Both male and female flies at four different age groups, reared on olives in the laboratory, were individually placed in glass tubes. Their locomotor activity was recorded every minute by three monitors within the digital device over a three-day period. Our observations revealed that adults exhibited significantly reduced movement during nighttime compared to daytime. The greatest mobility was observed during the period of 15:00 to 20:59. Additionally, younger flies demonstrated higher levels of mobility compared to older ones. Flies subjected to both food and water deprivation exhibited higher mobility compared to the control group. These insights offer valuable insights for enhancing pest management strategies aimed at controlling olive fruit flies adopting a more sustainable approach.

Competing Endogenous RNAs (ceRNAs) and Application of Their Regulatory Networks in Complex Traits and Diseases of Ruminants

This manuscript summarizes information on the diverse range of RNA molecules and their role as competing endogenous RNAs (ceRNAs). Moreover, it provides an overview of ceRNA regulatory networks and their applications in ruminant biology. Knowledge of co-expression networks has increased with microarrays, RNA-seq, and scRNA-seq characterizing molecular mediators across various biological scales, using sequences from numerous blood and tissue samples. By synthesizing existing knowledge, this study summarizes interactions between coding and non-coding RNAs through microRNA response elements (MREs), elucidating large-scale regulatory networks throughout the transcriptome that influence the expression and activities of various ceRNAs. Identification of non-coding RNAs with important regulatory functions will revolutionize understanding of RNA biology, shifting from an mRNA-centric model to a complex network of RNA crosstalk. The ceRNA networks offer a more comprehensive and arguably more realistic perspective compared to protein–protein interaction (PPI) networks and weighted gene co-expression networks (WGCN). These ceRNA regulatory networks can describe potential molecular regulatory mechanisms related to functional and economically important traits in ruminants, plus contribute to disease and pathology research, by elucidating pathogenesis and potential drug effects in disease and cancer models. Furthermore, they can provide insights into farm animal biology, e.g., reproductive traits in goats and sheep, regulation of fat metabolism in beef cattle, heat stress responses, and lactation regulation in dairy cattle, fertility and muscle characteristics in buffalo, and resistance to high-salt and water-deprivation conditions in camels. In conclusion, ceRNA and associated regulatory networks should promote a new understanding of molecular mechanisms and identify candidate genes and metabolic-signaling pathways in ruminants.

Water deprivation-induced hypoxia and oxidative stress physiology responses in respiratory organs of the Indian stinging fish in near coastal zones.

Water deprivation-induced hypoxia stress (WDIHS) has been extensively investigated in numerous fish species due to their adaptation with accessory respiratory organs to respire air but this has not been studied in Indian stinging fish Heteropneustes fossilis. Data regarding WDIHS-induced metabolism in accessory respiratory organ (ARO) and gills and its relationship with oxidative stress (OS) in respiratory organs of air-breathing fish H. fossilis, are limited. So, this study aimed to investigate the effects of WDIHS (0, 3, 6, 12, and 18 h) on hydrogen peroxide (H2O2) as reactive oxygen species (ROS), OS, redox regulatory enzymes, and electron transport enzymes (ETC) in ARO and gills of H. fossilis. Fish were exposed to air for different hours (up to 18 h) against an appropriate control, and ARO and gills were sampled. The levels of oxygen saturation in the body of the fish were assessed at various intervals during exposure to air. Protein carbonylation (PC) and thiobarbituric acid reactive substances (TBARS) were used as OS markers, H2O2 as ROS marker, and various enzymatic activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), along with the assessment of complex enzymes (I, II, III, and V) as well as the levels of ascorbic acid (AA) and the reduced glutathione (GSH) were quantified in both the tissues. Discriminant function analyses indicate a clear separation of the variables as a function of the studied parameters. The gills exhibited higher levels of GSH and H2O2 compared to ARO, while ARO showed elevated levels of PC, TBARS, AA, SOD, CAT, and GPx activities compared to the gills. The activities of GR and ETC enzymes exhibited similar levels in both the respiratory organs, namely the gills, and ARO. These organs experienced OS due to increased H2O2, TBARS, and PC levels, as observed during WDIHS. Under WDIHS conditions, the activity/level of CAT, GPx, GR, and GSH decreased in ARO, while SOD activity, along with GR, GSH, and AA levels decreased in gills. However, the activity/level of SOD and AA in ARO and CAT in gills was elevated under WDIHS. Complex II exhibited a positive correlation with WDIHS, while the other ETC enzymes (complex I, III, and V) activities had negative correlations with the WDIHS. The finding suggests that ARO is more susceptible to OS than gills under WDIHS. Despite both organs employ distinct redox regulatory systems to counteract this stress, their effectiveness is hampered by the inadequacy of small redox regulatory molecules and the compromised activity of the ETC, impeding their ability to effectively alleviate the stress induced by the water-deprivation condition.

Enhancing Drought Tolerance in Two Soybean Genotypes with Varied Susceptibilities Through Foliar Application of Acetic Acid

AbstractSoybean is a very important food legume because of its high protein and oil concentrations. However, soybean is vulnerable to drought stress, which has become more severe and occasional in many regions worldwide. To alleviate drought’s influence, the application of certain agents is increasingly gaining attention as it is economically affordable and practically applicable. Acetic acid (AA) is, by far, one of the cheapest agents that are reported to have potential benefits against drought; however, no accurate data on its influence on soybean genotypes differing in their drought tolerance are published. An experiment was conducted in a controlled environment to evaluate the effects of AA on the morpho-physiology of two soybean (Glycine max (L.) Merr.) genotypes: drought-tolerant ‘Speeda’ and drought-susceptible ‘Coraline.’ Chlorophyll-a and total carotenoids, stomatal conductance, and specific leaf area of both soybean genotypes decreased under water deprivation conditions. However, AA application enhanced these traits significantly. Drought reduced the optimal and the actual photochemical efficiency of PSII of ‘Coraline,’ but not ‘Speeda.’ The application of AA could not enhance the relative water content of both genotypes. Root and shoot morphology were negatively influenced by drought in both genotypes; however, AA helped in restoring these traits in ‘Coraline,’ but not ‘Speeda,’ indicating that AA application might be more beneficial in the case of drought-susceptible soybean genotypes.

Improving quality parameters of spinach by adjusting light spectra under moderate water deprivation conditions

Spinach (Spinacia oleracea L.) is a highly valuable leafy vegetable, abundant in vitamins, minerals, and antioxidants, offering various health benefits such as enhancing cardiovascular health, reducing inflammation, and aiding digestion. Consequently, it is crucial to effectively cultivate and maintain spinach's quality. Light plays a pivotal role in the growth and development of plants, including spinach, where different light qualities can influence its morpho-physiological traits and overall quality. To explore this, an experiment was conducted, using three distinct LED lighting sets for spinach cultivation. Light 1 emphasized blue light, Light 2 served as the standard white light control, and Light 3 focused more on red light with occasional brief UV-C flashes. Additionally, mild water deprivation was induced using 2.5% polyethylene glycol (PEG). The results revealed that using a high red-to-blue light ratio with intermittent UV-C radiation significantly reduced various growth parameters of spinach, such as root length, shoot length, root volume, fresh and dry root and shoot weight, as well as total and relative chlorophyll contents, when compared to the control group. Furthermore, water deprivation had a negative impact on spinach's growth, affecting shoot and root length, and fresh and dry weight in all light qualities, proving to be fatal under Light 3 conditions. Therefore, it is essential to carefully select appropriate light qualities throughout the plant's life cycle to enhance the quality of spinach, especially when mild water deprivation is involved. Opting for a higher blue-to-red light ratio was found to be somewhat beneficial in improving the overall quality of spinach.

Serum Activity of Proteolytic Enzyme Trypsin in Rats under Conditions of Water and Food Deprivation.

Trypsin is mainly regarded as a digestive enzyme, but there is evidence that activation of protease-activated receptor-2 (PAR-2) leads to behavioral changes. There are no data on trypsin activity in the serum of animals under conditions of thirst and starvation in the available literature. In our experiments, water deprivation led to a significant (p⩽0.05) increase in trypsin activity in rats, and food deprivation led to its decrease in comparison with controls (free access to water and food). After deprived rats received water and food, a decrease in trypsin activity was observed in both experimental groups. Changes in trypsin activity under conditions of water or food deprivation and after satiation were accompanied by shifts in some biochemical parameters of the bloods. Under conditions of metabolic stress (starvation and thirst), opposite changes in trypsin activity seem to indicate its participation in the mechanisms of adequate restructuring of metabolism and maintenance of vital processes in the body.

Drought Tolerance Evaluation and Verification of Fifty Pakchoi (Brassica rapa ssp. chinensis) Varieties under Water Deficit Condition

Reduced available water resources have become the main limiting factor for the production of leafy vegetable, such as pakchoi, which can be effectively addressed by growing water-efficient varieties. Therefore, it is particularly important for evaluation and verification of drought tolerant varieties. In this study, 50 different varieties of pakchoi were detected for their morphological and physiological indicators under both normal-irrigated and water-deficiency environments. Based on systematic analysis of these evaluation indicators using different evaluation methods, the significant indicators were identified and the prediction model was established followed by validation of different drought tolerant of pakchoi varieties. The results showed that considerable differences were observed in all the indicators detected under conditions of water deprivation compared with normal irrigation. Frequency distribution revealed that the indictors sensitivity with significant changes to water-deficient conditions was ordered as follows: aboveground fresh and dry weight, followed by belowground fresh and dry weight, root volume, root length, root activity, and soluble sugar. Correlation analysis showed that each indicator was significantly or extremely significantly associated with other indices, indicating that there is a certain degree of association between the indices. Principal component analysis (PCA) turned 16 indicators into four independent components, with a cumulative contribution ratio of 80.147%. According to the results of drought tolerance comprehensive evaluation value (D-value) analysis and cluster analysis, 50 varieties were ranked in relation to drought tolerance and classified into five categories, among them Jinhui, Qingguan, Dongyue, Xiazhijiao, and Hanszifei, which were classified as highly drought-tolerant cultivars. Moreover, the stepwise regression model was established and demonstrated that soluble sugar, average root diameter, belowground fresh weight, root volume, and leaf number were selected as key indicators which can be used for screening and identifying drought-pakchoi varieties. Furthermore, the tolerance capacity of pakchoi varieties was further validated using one representative variety selected from five groups and treated with water-deficit stress. It was demonstrated that the established model was verified consistent with drought tolerance of pakchoi varieties, and tolerance capacity was closely related to increasing epidermal stomatal density, maintaining high photosynthesis, and increasing antioxidant enzyme activity to reduce damage (ROS). The results proposed the key drought tolerance indicators and evaluation methods, which provide the basis for the screening of leaf-vegetable varieties with different drought-tolerances, as well the identified varieties could be used for effective water-saving production.

A Comparison of Different Stomatal Density Phenotypes of Hordeum vulgare under Varied Watering Regimes Reveals Superior Genotypes with Enhanced Drought Tolerance.

Enhancing the water-use efficiency (WUE) of barley cultivars may safeguard yield deficits during periods of low rainfall. Reduced stomatal density is linked to enhanced WUE, leading to improved drought resistance across plant genera. In this study, 10 barley varieties exhibiting a range of stomatal density phenotypes were grown under differing soil water contents to determine whether stomatal density influences the capacity of genotypes to resist low water availability. The low-stomatal-density genotype Hindmarsh showed the least impact on biomass production during early development, with a 37.13% decrease in dry biomass during drought treatment. Low-stomatal-density genotypes additionally outcompeted high-stomatal-density genotypes under water-deprivation conditions during the reproductive phase of development, exhibiting 19.35% greater wilting resistance and generating 54.62% more heads relative to high-stomatal-density genotypes (p < 0.05). Finally, a correlation analysis revealed a strong negative linear relationship between stomatal density and the traits of head number (r = -0.71) and the number of days until wilting symptoms (r = -0.67) (p < 0.05). The combined results indicate that low-stomatal-density genotypes show promising attributes for high WUE, revealing novel barley varieties that may be useful to future breed improvement for drought tolerance.

Disinhibition augments thirst perception from two dehydrating stimuli in men

Physiological systems controlling water and energy ingestion are coordinated. Whether maladaptive eating behavior and appetite for water are linked is unknown. Thus, we sought to investigate the association between maladaptive eating and both thirst and water drinking behavior with two dehydrating conditions. Twenty-two lean men and 20 men with obesity (mean age 32.3 ± 8.4 years and 30.0 ± 11.1 years, respectively) completed the Three-Factor Eating Questionnaire (TFEQ) and Gormally Binge Eating Scale. On separate days, volunteers were dehydrated by a 2-h hypertonic saline infusion and a 24-h water deprivation, and thirst was measured on a 100-mm visual analogue scale (VAS) during each procedure. After each dehydrating condition, ad libitum water intake was measured. In the saline infusion, higher Disinhibition on the TFEQ was associated with thirst in the lean group (β = 4.2 mm VAS, p = 0.03) but not in the group with obesity (p = 0.51). In the water-deprivation condition, higher Disinhibition was also associated with thirst in the lean group (β = 5.6 mm VAS, p = 0.01) with the strength of relationship being 3.5-fold stronger than that observed in the group with obesity (β = 1.6 mm VAS, p = 0.0003). Hunger, Restraint, and binge-eating scores were not associated with thirst in either dehydrating condition (all p > 0.05). Maladaptive eating behaviors were not associated with ad libitum water intake (all p > 0.05). Disinhibition is associated with higher thirst perception in healthy weight individuals and may be attenuated in obesity. The characteristics of disinhibition which typically includes a heightened readiness to eat, may reflect a more general phenotype that also reflects a readiness to drink.

Air sac and gill vasotocin receptor gene expression in the air-breathing catfish Heteropneustes fossilis exposed to water and air deprivation conditions.

Heteropneustes fossilis is a facultative air-breathing freshwater catfish and inhabits ponds, ditches, swamps, marshes and rivers that dry up in summers. It possesses a pair of unique tubular accessory respiratory organ (air sac), which is a modification of the gill chamber and enables it to live in water-air transition zones. In the catfish, three vasotocin (Vt) receptor gene paralogs viz., v1a1, v1a2 and v2a were identified for Vt actions. In the present study, the receptor gene transcripts were localized in the gill and air sac by in situ hybridization, and their expression levels in relation to water and air deprivation conditions were investigated by quantitative RT-PCR. The catfish were exposed to 1h and 2h in gonad inactive (resting) and gonad active (prespawning) phases. The gene paralogs showed overlapping distribution in the respiratory epithelium of primary and secondary lamellae of gills and reduced lamellae of the air sacs. In water deprivation (forced aerial mode of respiration) experiment, v2a expression showed a high fold increase in the air sac, which was unchanged or inhibited in the gill. Both v1a1 and v1a2 expression was significantly upregulated in the air sac but showed varied responses in the gill. The gill v1a1 expression was unchanged in the resting phase and modestly upregulated in the prespawning phase. The gill v1a2 expression was modestly upregulated at 1h in both phases but unchanged at 2h. In the air deprivation experiment (forced aquatic respiration), the v2a expression in the air sac was inhibited except for a mild stimulation at 1h in the prespawning phase. In the gill, the v2a expression was stimulated with a steep upregulation at 2h in the prespawning phase. Both v1a1 and v1a2 expression was significantly high in the gill but only modestly increased or unchanged in the air sac. The expression patterns point to a functional distinction; the V2 type receptor expression was higher in the air sac during forced aerial respiration, and the V1 type receptor expression was highly prominent in the gill during forced aquatic respiration. Water and air deprivation treatments caused a significant increase in plasma cortisol level, and the stimulation was higher in the water deprivation fish in the resting phase but equally prominent in the water and air deprivation groups in the prespawning phase. The results indicate that the changes in the expression patterns of Vt receptor genes may be a sequel to stress (hypoxic, metabolic and osmotic), and both Vt and cortisol may interact to counter the stress responses. This study shows that Vt has a new role in the control of air sac functions.

Responsiveness of Early Response to Dehydration Six-Like Transporter Genes to Water Deficit in Arabidopsis thaliana Leaves.

Drought is one of the main abiotic stresses, which affects plant growth, development, and crop yield. Plant response to drought implies carbon allocation to sink organs and sugar partitioning between different cell compartments, and thereby requires the involvement of sugar transporters (SUTs). Among them, the early response to dehydration six-like (ESL), with 19 members in Arabidopsis thaliana, form the largest subfamily of monosaccharide transporters (MSTs) still poorly characterized. A common feature of these genes is their involvement in plant response to abiotic stresses, including water deficit. In this context, we carried out morphological and physiological phenotyping of A. thaliana plants grown under well-watered (WW) and water-deprived (WD) conditions, together with the expression profiling of 17 AtESL genes in rosette leaves. The drought responsiveness of 12 ESL genes, 4 upregulated and 8 downregulated, was correlated to different water statuses of rosette leaves. The differential expression of each of the tandem duplicated AtESL genes in response to water stress is in favor of their plausible functional diversity. Furthermore, transfer DNA (T-DNA) insertional mutants for each of the four upregulated ESLs in response to water deprivation were identified and characterized under WW and WD conditions. To gain insights into global sugar exchanges between vacuole and cytosol under water deficit, the gene expression of other vacuolar SUTs and invertases (AtTMT, AtSUC, AtSWEET, and AtβFRUCT) was analyzed and discussed.

ANG II and Aldosterone Acting Centrally Participate in the Enhanced Sodium Intake in Water-Deprived Renovascular Hypertensive Rats.

Renovascular hypertension is a type of secondary hypertension caused by renal artery stenosis, leading to an increase in the renin–angiotensin–aldosterone system (RAAS). Two-kidney, 1-clip (2K1C) is a model of renovascular hypertension in which rats have an increased sodium intake induced by water deprivation (WD), a common situation found in the nature. In addition, a high-sodium diet in 2K1C rats induces glomerular lesion. Therefore, the purpose of this study was to investigate whether angiotensin II (ANG II) and/or aldosterone participates in the increased sodium intake in 2K1C rats under WD. In addition, we also verified if central AT1 and mineralocorticoid receptor blockade would change the high levels of arterial pressure in water-replete (WR) and WD 2K1C rats, because blood pressure changes can facilitate or inhibit water and sodium intake. Finally, possible central areas activated during WD or WD followed by partial rehydration (PR) in 2K1C rats were also investigated. Male Holtzman rats (150–180 g) received a silver clip around the left renal artery to induce renovascular hypertension. Six weeks after renal surgery, a stainless-steel cannula was implanted in the lateral ventricle, followed by 5–7 days of recovery before starting tests. Losartan (AT1 receptor antagonist) injected intracerebroventricularly attenuated water intake during the thirst test. Either icv losartan or RU28318 (mineralocorticoid receptor antagonist) reduced 0.3 M NaCl intake, whereas the combination of losartan and RU28318 icv totally blocked 0.3 M NaCl intake induced by WD in 2K1C rats. Losartan and RU28318 icv did not change hypertension levels of normohydrated 2K1C rats, but reduced the increase in mean arterial pressure (MAP) produced by WD. c-Fos expression increased in the lamina terminalis and in the NTS in WD condition, and increased even more after WD-PR. These results suggest the participation of ANG II and aldosterone acting centrally in the enhanced sodium intake in WD 2K1C rats, and not in the maintenance of hypertension in satiated and fluid-replete 2K1C rats.

The N uptake-associated physiological processes at late growth stage in wheat (Triticum aestivum) under N deprivation combined with deficit irrigation condition

Elucidating physiological mechanisms underlying the plant N uptake benefits breeding of high N use efficiency (NUE) crop cultivars. In this study, we investigated the growth and N uptake-associated processes in wheat under N deprivation and deficit irrigation, using two contrasting NUE cultivars. Compared with sufficient-N (SN), deficient-N (DN) treatment reduced plant biomass, N accumulation, and yields in two cultivars (high NUE Shinong 086 and N deprivation-sensitive Jimai 585), suggesting that N deprivation negatively regulates plant growth and N uptake. Shinong 086 was better on growth and N uptake-associated traits than Jimai 585 due to the improved root biomass across soil profile, which was consistent with the decrease of available N contents in soil layers. These results suggested that the improved root system architecture (RAS) enhances plant acquirement for soil N under N- and water-deprivation condition, contributing to the plant N uptake and yield formation capacities. Transcriptome investigation revealed that numerous genes were differentially expressed (DE) in the N-deprived Shinong 086 plants, which involve the regulation of complicate biochemical pathways. These results suggested that the modified RAS and N uptake in high NUE plants are accomplished underlying the regulation of numerous DE genes. TaWRKY20, a gene in ZFP transcription factor family, was functionally characterized for the role in mediating plant N uptake. Overexpression of it conferred plants improved growth and N uptake under DN due to its regulation on TaNRT2.1 and TaNRT2.2, two nitrate transporter genes. Our investigation provides insights in high NUE mechanisms in wheat under N deprivation.

Transcriptional modulation of AREB-1 by CRISPRa improves plant physiological performance under severe water deficit

Plants are sessile organisms, which are vulnerable to environmental stresses. As such, plants have developed multiple molecular, physiological, and cellular mechanisms to cope with natural stressors. However, these environmental adversities, including drought, are sources of the main agribusiness problems since they interfere with plant growth and productivity. Particularly under water deprivation conditions, the abscisic acid-responsive element-binding protein AREB1/ABF2 plays an important role in drought stress response and physiological adaptation. In this investigation, we provide substantial confirmation for the role of AREB1/ABF2 in plant survival under severe water deficit using the CRISPR activation (CRISPRa) technique to enhance the AREB1 gene expression. In our strategy, the inactive nuclease dCas9 was fused with an Arabidopsis histone acetyltransferase 1, which improves gene expression by remodeling chromatin. The AREB1 overexpression promotes an improvement in the physiological performance of the transgenic homozygous plants under drought, which was associated with an increase in chlorophyll content, antioxidant enzyme activity, and soluble sugar accumulation, leading to lower reactive oxygen species accumulation. Finally, we found that the CRISPR-mediated up-regulation of AREB1 changes the abundance of several downstream ABA-inducible genes, allowing us to report that CRISPRa dCas9-HAT is a valuable biotechnological tool to improve drought stress tolerance through the positive regulation of AREB1.

Evidence from ileum and liver transcriptomes of resistance to high-salt and water-deprivation conditions in camel

Camels have evolved various resistance characteristics adaptive to their desert habitats. In the present study, we used high-throughput sequencing to investigate stress-induced alternative splicing events as well as different genes involved in resistance to water deprivation and salt absorption in the ileum and liver in Camelus bactrianus. Through association analyses of mRNA, miRNA and lncRNA, we sought to explicate how camels respond to high salt and water scarcity conditions. There were two modes by which genes driven by alternative splicing were enriched to molecular functions, invoking of which was potentially fixed by organ and stress types. With qRT-PCR detection, the differentially expressed MUC6, AQP5, LOC105076960, PKP4, CDH11, TENM1, SDS, LOC105061856, PLIN2 and UPP2 were screened as functionally important genes, along with miR-29b, miR-484, miR-362-5p, miR-96, miR-195, miR-128 and miR-148a. These genes contributed to cellular stress resistance, for instance by reducing water loss, inhibiting excessive import of sodium, improving protective barriers and sodium ion homeostasis, and maintaining uridine content. The underlying competing endogenous RNAs referred to LNC001664, let-7e and LOC105076960 mRNA in ileum, and LNC001438, LNC003417, LNC001770, miR-199c and TENM1 mRNA in liver. Besides competent interpretation to resistance, there may be inspirations for curing human diseases triggered by high-salt intake.

Screening of drought-resistance related genes and analysis of promising regulatory pathway in camel renal medulla

Camels as a sort of animal long living in desert have evolved stress-resistance characteristics to adapt to environment with high temperature and water shortage environment. However, the research of non-coding RNA (ncRNA)-mediated molecular regulation about how camel responds to arid condition in post-transcriptional regulation level is deficient. Under water-deprivation stress, by RNA-sequencing of camel renal medulla associated with regulating water metabolism, we detected significantly differential 575 alternative splicing events (ASEs) and 17 mRNAs, 26 miRNAs and 0 lncRNA. The down-regulated ACLY and LOC105061856, up-regulated PCBP2 and miR-195 potentially targeting LOC105061856 and PCBP2 mRNA were selected as candidate resistance-related genes. In quantitative experiment, the expression level of above four genes was consistent with RNA-seq data by qRT-PCR. The suppressive cell dehydration with down-regulated ACLY, inhibitive aerobic respiration with down-regulated LOC105061856 targeted by miR-195 and strong anti-oxidative capability with PCBP2 aimed by miR-195 may be regulatory modes of camel renal medulla adapting to water-deprivation condition.

The complex response of free and bound amino acids to water stress during the seed setting stage in Arabidopsis

Free amino acids (FAAs) and protein-bound amino acids (PBAAs) in seeds play an important role in seed desiccation, longevity, and germination. However, the effect that water stress has on these two functional pools, especially when imposed during the crucial seed setting stage is unclear. To better understand these effects, we exposed Arabidopsis plants at the seed setting stage to a range of water limitation and water deprivation conditions and then evaluated physiological, metabolic, and proteomic parameters, with special focus on FAAs and PBAAs. We found that in response to severe water limitation, seed yield decreased, while seed weight, FAA, and PBAA content per seed increased. Nevertheless, the composition of FAAs and PBAAs remained unaltered. In response to severe water deprivation, however, both seed yield and weight were reduced. In addition, major alterations were observed in both FAA and proteome compositions, which indicated that both osmotic adjustment and proteomic reprogramming occurred in these naturally desiccation-tolerant organs. However, despite the major proteomic alteration, the PBAA composition did not change, suggesting that the proteomic reprogramming was followed by a proteomic rebalancing. Proteomic rebalancing has not been observed previously in response to stress, but its occurrence under stress strongly suggests its natural function. Together, our data show that the dry seed PBAA composition plays a key role in seed fitness and therefore is rigorously maintained even under severe water stress, while the FAA composition is more plastic and adaptable to changing environments, and that both functional pools are distinctly regulated.