Effects of exogenous calcium and calcium inhibitor on physiological characteristics of winter turnip rape (Brassica rapa) under low temperature stress.

Low temperature is one of the environmental factors that restrict the growth and geographical distribution of Brassica. To investigate the effects of exogenous calcium and calcium inhibitor on the ability of winter turnip rapeseed (Brassica rapa L.) to withstand low temperatures (4℃), we used a strong cold-resistant variety Longyou 7 (L7) and a weak cold-resistant variety Longyou 99 (L99) as the materials. The seedlings were treated with CaCl2 (20 mmol·L-1) and calcium inhibitor LaCl3 (10 mmol·L-1) at 0 h (CK), 6 h, 12 h, 24 h and 48 h after 4℃ treatments. Physiological characteristics, Ca2+ flux and Ca2+ concentration in roots after treatments were analyzed. Results illustrated that under 4℃ treatment, activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) increased by both CK and exogenous CaCl2 treatments. Contents of soluble protein (SP) and proline (Pro) increased, while contents of malondialdehyde (MDA) decreased, resulting in reduced membrane lipid peroxidation. But enzyme activity decreased and MDA content increased following treatment with exogenous LaCl3. The rate of Ca2+ flow showed a higher uptake in L7 roots compared with L99. L99 showed Ca2+ efflux with a rate of 30.21 pmol‧cm-2‧s-1, whereas L7 showed short efflux then returned to influx. Calcium ion content in roots decreased in both cultivars after CaCl2 treatment. Results of RNA-seq revealed that genes were differentially expressed in response to low temperatures, hormones, photosystem II, chloroplasts, DNA replication, ribosomal RNA processing, and translation. This study found significant expression genes related to cellular signal transduction (MAPK signaling pathway) and material metabolism (nitrogen metabolism, glycerol ester metabolism).It was also analyzed by WGCNA that two modules had the strongest correlation with physiological indicators. Eight candidate genes were identified among MAPK signaling pathway and the two modules.

Analysis of the Mechanism of Wood Vinegar and Butyrolactone Promoting Rapeseed Growth and Improving Low-Temperature Stress Resistance Based on Transcriptome and Metabolomics.

Rapeseed is an important oil crop in the world. Wood vinegar could increase the yield and abiotic resistance of rapeseed. However, little is known about the underlying mechanisms of wood vinegar or its valid chemical components on rapeseed. In the present study, wood vinegar and butyrolactone (γ-Butyrolactone, one of the main components of wood vinegar) were applied to rapeseed at the seedling stage, and the molecular mechanisms of wood vinegar that affect rapeseed were studied by combining transcriptome and metabolomic analyses. The results show that applying wood vinegar and butyrolactone increases the biomass of rapeseed by increasing the leaf area and the number of pods per plant, and enhances the tolerance of rapeseed under low temperature by reducing membrane lipid oxidation and improving the content of chlorophyll, proline, soluble sugar, and antioxidant enzymes. Compared to the control, 681 and 700 differentially expressed genes were in the transcriptional group treated with wood vinegar and butyrolactone, respectively, and 76 and 90 differentially expressed metabolites were in the metabolic group. The combination of transcriptome and metabolomic analyses revealed the key gene-metabolic networks related to various pathways. Our research shows that after wood vinegar and butyrolactone treatment, the amino acid biosynthesis pathway of rapeseed may be involved in mediating the increase in rapeseed biomass, the proline metabolism pathway of wood vinegar treatment may be involved in mediating rapeseed's resistance to low-temperature stress, and the sphingolipid metabolism pathway of butyrolactone treatment may be involved in mediating rapeseed's resistance to low-temperature stress. It is suggested that the use of wood vinegar or butyrolactone are new approaches to increasing rapeseed yield and low-temperature resistance.

Exogenous strigolactones alleviate low-temperature stress in peppers seedlings by reducing the degree of photoinhibition.

BACKGROUND: The growth and yield of pepper, a typical temperature-loving vegetable, are limited by low-temperature environments. Using low-temperature sensitive 'Hangjiao No. 4' (Capsicum annuum L.) as experimental material, this study analyzed the changes in plant growth and photosynthesis under different treatments: normal control (NT), low-temperature stress alone (LT), low-temperature stress in strigolactone pretreated plants (SL_LT), and low-temperature stress in strigolactone biosynthesis inhibitor pretreated plants (Tis_LT). RESULTS: SL pretreatment increased the net photosynthetic rate (Pn) and PSII actual photochemical efficiency (φPSII), reducing the inhibition of LT on the growth of pepper by 17.44% (dry weight of shoot). Due to promoting the accumulation of carotenoids, such as lutein, and the de-epoxidation of the xanthophyll cycle [(Z + A)/(Z + A + V)] by strigolactone after long-term low-temperature stress (120 h), non-photochemical quenching (NPQ) of pepper was increased to reduce the excess excitation energy [(1-qP)/NPQ] and the photoinhibition degree (Fv/Fm) of pepper seedlings under long-term low-temperature stress was alleviated. Twelve cDNA libraries were constructed from pepper leaves by transcriptome sequencing. There were 8776 differentially expressed genes (DEGs), including 4473 (51.0%) upregulated and 4303 (49.0%) downregulated genes. Gene ontology pathway annotation showed that based on LT, the DEGs of SL_LT and Tis_LT were significantly enriched in the cellular component, which is mainly related to the photosystem and thylakoids. Further analysis of the porphyrin and chlorophyll biosynthesis, carotenoid biosynthesis, photosynthesis-antenna protein, and photosynthetic metabolic pathways and the Calvin cycle under low-temperature stress highlighted 18, 15, 21, 29, and 31 DEGs for further study, which were almost all highly expressed under SL_LT treatment and moderately expressed under LT treatment, whereas Tis_LT showed low expression. CONCLUSION: The positive regulatory effect of SLs on the low-temperature tolerance of pepper seedlings was confirmed. This study provided new insights for the development of temperature-tolerant pepper lines through breeding programs.

Effect of vitamin E on energy metabolism indicators and gill tissue structure of crucian carp (Carassius auratus) under cooling stress.

The aim of this work is to examine the effects of vitamin E addition to water on the structure of the gill tissue and energy metabolism of crucian carp (Carassius auratus) under cooling stress. The crucian carp were chilled using a cold acclimation intelligent chilling equipment from 20 °C to 5 °C. They were divided into three groups: the control group (E1), the negative control group (E2), and the 100 mg/L vitamin E (E3) solution. Three different temperature points (20 °C, 10 °C, and 5 °C) were used to collect, test, and analyze the samples. The findings demonstrated that in the E3 treatment group, phosphoenolpyruvate carboxykinase, acetyl coenzyme A carboxylase, total cholesterol, urea nitrogen, triglyceride, and fatty acid synthase contents were significantly lower under cooling stress than those in the E1 and E2 treatment groups (P < 0.05). The E3 therapy group had significantly greater blood glucose, glycogen, and glycogen synthase levels than the E1 and E2 treatment groups (P < 0.05). The levels of pyruvate kinase in the E1, E2, and E3 treatment groups did not differ significantly. Crucian carp's gill tissue changed under cooling stress, including capillary dilatation, and the E3 treatment group experienced less damage overall than the E1 and E2 treatment groups. In conclusion, supplementing water with vitamin E to treat crucian carp can decrease damage, improve the body's ability to withstand cold, and slow down the stress response brought on by cooling stress. This provides a theoretical basis for supplementing water with vitamin E to fish stress relief.

Discovery of gene regulation mechanisms associated with uniconazole-induced cold tolerance in banana using integrated transcriptome and metabolome analysis.

BACKGROUND: The gibberellic acid (GA) inhibitor, uniconazole, is a plant growth regulator commonly used in banana cultivation to promote dwarfing but also enhances the cold resistance in plants. However, the mechanism of this induced cold resistance remains unclear. RESULTS: We confirmed that uniconazole induced cold tolerance in bananas and that the activities of Superoxide dismutase and Peroxidase were increased in the uniconazole-treated bananas under cold stress when compared with the control groups. The transcriptome and metabolome of bananas treated with or without uniconazole were analyzed at different time points under cold stress. Compared to the control group, differentially expressed genes (DEGs) between adjacent time points in each uniconazole-treated group were enriched in plant-pathogen interactions, MAPK signaling pathway, and plant hormone signal transduction, which were closely related to stimulus-functional responses. Furthermore, the differentially abundant metabolites (DAMs) between adjacent time points were enriched in flavone and flavonol biosynthesis and linoleic acid metabolism pathways in the uniconazole-treated group than those in the control group. Temporal analysis of DEGs and DAMs in uniconazole-treated and control groups during cold stress showed that the different expression patterns in the two groups were enriched in the linoleic acid metabolism pathway. In addition to strengthening the antioxidant system and complex hormonal changes caused by GA inhibition, an enhanced linoleic acid metabolism can protect cell membrane stability, which may also be an important part of the cold resistance mechanism of uniconazole treatment in banana plants. CONCLUSIONS: This study provides information for understanding the mechanisms underlying inducible cold resistance in banana, which will benefit the production of this economically important crop.

[Study on drug properties of Arisaematis Rhizoma and Arisaema Cum Bile based on substance and energy metabolism in normal and cold/heat syndrome model rats].

This paper clarified the scientific connotation of the changes in cold and heat properties of Arisaematis Rhizoma and Arisaema Cum Bile through investigating the changes of substance and energy metabolism after drug intervention in the rats with normal and cold/heat syndrome, so as to improve the method of evaluating the drug properties of Chinese medicine. After one week of adaptive feeding, healthy male SD rats were randomly divided into three parts: normal rats, heat syndrome rat models, and cold syndrome rat models. Through ice water bath and oral euthyrox(120 µg·kg~(-1)), the models of cold syndrome and heat syndrome were induced, respectively. The models were made at 9:00 am. and administrated by gavage at 3:00 pm. every day. All administration groups were administrated with Arisaematis Rhizoma and Arisaema Cum Bile decoction, respectively, and the blank group was given the same dose of normal saline. After continuous administration for 15 d, the rats were anesthetized by chloral hydrate, blood was taken from abdominal aorta, and the hearts and livers were removed and stored at-80 ℃. The changes in the body weight and anal temperature of rats during administration were detected, and the liver coefficient of rats was detected after removing the liver. Enzyme-linked immunosorbent assay(ELISA) was adopted to detect the expression level of the indexes related to substance and energy metabolism in liver and heart of rat, and Western blot was used to detect the expression of key proteins in AMPK/mTOR signaling pathway for further verification. The results showed that Arisaematis Rhizoma enhanced the expression level of enzymes related to substance and energy metabolism in the normal and cold and heat syndrome rat models, and increased anal temperature, which exhibited warm(hot) drug property. Arisaema Cum Bile inhibited the level of substance and energy metabolism in rats, and reduced anal temperature, which showed cold(cool) drug property. Chinese Pharmacopoeia has recorded "Arisaematis Rhizoma has warm property and Arisaema Cum Bile has cool property", which is consistent with the phenomenon in this study. Therefore, it is feasible to evaluate the drug properties of Chinese medicine based on the substance and energy metabolism of normal and cold/heat syndrome model rats, which completes the method of evaluating drug properties of Chinese medicine.

Hydrogen Sulfide Improves the Cold Stress Resistance through the CsARF5-CsDREB3 Module in Cucumber.

As an important gas signaling molecule, hydrogen sulfide (H2S) plays a crucial role in regulating cold tolerance. H2S cooperates with phytohormones such as abscisic acid, ethylene, and salicylic acid to regulate the plant stress response. However, the synergistic regulation of H2S and auxin in the plant response to cold stress has not been reported. This study showed that sodium hydrosulfide (NaHS, an H2S donor) treatment enhanced the cold stress tolerance of cucumber seedlings and increased the level of auxin. CsARF5, a cucumber auxin response factor (ARF) gene, was isolated, and its role in regulating H2S-mediated cold stress tolerance was described. Transgenic cucumber leaves overexpressing CsARF5 were obtained. Physiological analysis indicated that overexpression of CsARF5 enhanced the cold stress tolerance of cucumber and the regulation of the cold stress response by CsARF5 depends on H2S. In addition, molecular assays showed that CsARF5 modulated cold stress response by directly activating the expression of the dehydration-responsive element-binding (DREB)/C-repeat binding factor (CBF) gene CsDREB3, which was identified as a positive regulator of cold stress. Taken together, the above results suggest that CsARF5 plays an important role in H2S-mediated cold stress in cucumber. These results shed light on the molecular mechanism by which H2S regulates cold stress response by mediating auxin signaling; this will provide insights for further studies on the molecular mechanism by which H2S regulates cold stress. The aim of this study was to explore the molecular mechanism of H2S regulating cold tolerance of cucumber seedlings and provide a theoretical basis for the further study of cucumber cultivation and environmental adaptability technology in winter.

Metabolic activities and molecular investigations of the ameliorative impact of some growth biostimulators on chilling-stressed coriander (Coriandrum sativum L.) plant.

BACKGROUND: Priming of seed prior chilling is regarded as one of the methods to promote seeds germination, whole plant growth, and yield components. The application of biostimulants was reported as beneficial for protecting many plants from biotic or abiotic stresses. Their value was as important to be involved in improving the growth parameters of plants. Also, they were practiced in the regulation of various metabolic pathways to enhance acclimation and tolerance in coriander against chilling stress. To our knowledge, little is deciphered about the molecular mechanisms underpinning the ameliorative impact of biostimulants in the context of understanding the link and overlap between improved morphological characters, induced metabolic processes, and upregulated gene expression. In this study, the ameliorative effect(s) of potassium silicate, HA, and gamma radiation on acclimation of coriander to tolerate chilling stress was evaluated by integrating the data of growth, yield, physiological and molecular aspects. RESULTS: Plant growth, yield components, and metabolic activities were generally diminished in chilling-stressed coriander plants. On the other hand, levels of ABA and soluble sugars were increased. Alleviation treatment by humic acid, followed by silicate and gamma irradiation, has notably promoted plant growth parameters and yield components in chilling-stressed coriander plants. This improvement was concomitant with a significant increase in phytohormones, photosynthetic pigments, carbohydrate contents, antioxidants defense system, and induction of large subunit of RuBisCO enzyme production. The assembly of Toc complex subunits was maintained, and even their expression was stimulated (especially Toc75 and Toc 34) upon alleviation of the chilling stress by applied biostimulators. Collectively, humic acid was the best the element to alleviate the adverse effects of chilling stress on growth and productivity of coriander. CONCLUSIONS: It could be suggested that the inducing effect of the pretreatments on hormonal balance triggered an increase in IAA + GA3/ABA hormonal ratio. This ratio could be linked and engaged with the protection of cellular metabolic activities from chilling injury against the whole plant life cycle. Therefore, it was speculated that seed priming in humic acid is a powerful technique that can benefit the chilled along with non-chilled plants and sustain the economic importance of coriander plant productivity.

Melatonin Application Modifies Antioxidant Defense and Induces Endoreplication in Maize Seeds Exposed to Chilling Stress.

The aim of the study was to demonstrate the biostimulating effect of exogenous melatonin (MEL) applied to seeds via hydroconditioning. It was indicated that only well-chosen application technique and MEL dose guarantees success concerning seed germination and young seedlings growth under stress conditions. For maize seed, 50 µM of MEL appeared to be the optimal dose. It improved seed germination and embryonic axes growth especially during chilling stress (5 °C/14 days) and during regeneration after its subsided. Unfortunately, MEL overdosing lowered IAA level in dry seeds and could disrupt the ROS-dependent signal transduction pathways. Very effective antioxidant MEL action was confirmed by low level of protein oxidative damage and smaller quantity of lipid oxidation products in embryonic axes isolated from seeds pre-treated with MEL and then exposed to cold. The stimulatory effects of MEL on antioxidant enzymes: SOD, APX and GSH-PX and on GST-a detoxifying enzyme, was also demonstrated. It was indicated for the first time, that MEL induced defence strategies against stress at the cytological level, as appearing endoreplication in embryonic axes cells even in the seeds germinating under optimal conditions (preventive action), but very intensively in those germinating under chilling stress conditions (intervention action), and after stress removal, to improve regeneration.

Genistein improves systemic metabolism and enhances cold resistance by promoting adipose tissue beiging.

Genistein, a naturally occurring phytoestrogen and a member of the large class of compounds known as isoflavones, exerts protective effects in several diseases. Recent studies indicate that genistein plays a critical role in controlling body weight, obesity-associated insulin resistance, and metabolic disorders, but its target organs in reversing obesity and related pathological conditions remain unclear. In this study, we showed that mice supplemented with 0.2% genistein in a high-fat diet for 12 weeks showed enhanced metabolic homeostasis, including reduced obesity, improved glucose uptake and insulin sensitivity, and alleviated hepatic steatosis. We also observed a beiging phenomenon in the white adipose tissue and reversal of brown adipose tissue whitening in these mice. These changes led to enhanced resistance to cold stress. Altogether, our data suggest that the improved metabolic profile in mice treated with genistein is likely a result of enhanced adipose tissue function.

Packham's Triumph Pears (Pyrus communis L.) Post-Harvest Treatment during Cold Storage Based on Chitosan and Rue Essential Oil.

Pears (Pyrus communis L.) cv. Packham's Triumph are very traditional for human consumption, but pear is a highly perishable climacteric fruit with a short shelf-life affected by several diseases with a microbial origin. In this study, a protective effect on the quality properties of pears was evidenced after the surface application of chitosan-Ruta graveolens essential oil coatings (CS + RGEO) in four different concentrations (0, 0.5, 1.0 and 1.5 %, v/v) during 21 days of storage under 18 °C. After 21 days of treatment, a weight loss reduction of 10% (from 40.2 ± 5.3 to 20.3 ± 3.9) compared to the uncoated pears was evident with CS + RGEO 0.5%. All the fruits' physical-chemical properties evidenced a protective effect of the coatings. The maturity index increased for all the treatments. However, the pears with CS + RGEO 1.5% were lower (70.21) than the uncoated fruits (98.96). The loss of firmness for the uncoated samples was higher compared to the coated samples. The pears' most excellent mechanical resistance was obtained with CS + RGEO 0.5% after 21 days of storage, both for compression resistance (7.42 kPa) and force (22.7 N). Microbiological studies demonstrated the protective power of the coatings. Aerobic mesophilic bacteria and molds were significantly reduced (in 3 Log CFU/g compared to control) using 15 µL/mL of RGEO, without affecting consumer perception. The results presented in this study showed that CS + RGEO coatings are promising in the post-harvest treatment of pears.

The effects of melatonin daily supplementation to aged rats on the ability to withstand cold, thermoregulation and body weight.

AIMS: Investigate the role of melatonin on the regulation of body temperature in aged animals that have impaired melatonin production. MATERIAL AND METHODS: Aged Male Wistar rats were randomly assigned to the following groups: 1) control (vehicle added to the water bottles during the dark phase) and 2) melatonin-treated (10 mg/kg melatonin added to the water bottles during the dark phase). Before and after 16 weeks of vehicle or melatonin treatment, control group and melatonin-treated animals were acutely exposed to 18 °C for 2 h for an acute cold challenge and thermal images were obtained using an infrared camera. After 16 weeks, animals were euthanized and brown and beige adipocytes were collected for analysis of genes involved in the thermogenesis process by real-time PCR, and the uncoupling protein expression was evaluated by immunoblotting. Browning intensity of beige adipocytes were quantified by staining with hematoxylin-eosin. KEY FINDINGS: Chronic melatonin supplementation induced a minor increase in body mass and increased the animal's thermogenic potential in the cold acute challenge. Brown and beige adipocytes acted in a coordinated and complementary way to ensure adequate heat production. SIGNIFICANCE: Melatonin plays an important role in the thermoregulatory mechanisms, ensuring greater capacity to withstand cold and, also, participating in the regulation of energy balance.

Pharmacological modulation of RORα controls fat browning, adaptive thermogenesis, and body weight in mice.

Beiging is an attractive therapeutic strategy to fight against obesity and its side metabolic complications. The loss of function of the nuclear transcription factor RORα has been related to a lean phenotype with higher thermogenesis in sg/sg mice lacking this protein. Here we show that pharmacological modulation of RORα activity exerts reciprocal and cell-autonomous effect on UCP1 expression ex vivo, in cellulo, and in vivo. The RORα inverse-agonist SR3335 upregulated UCP1 expression in brown and subcutaneous white adipose tissue (scWAT) explants of wild-type (WT) mice, whereas the RORα agonist SR1078 had the opposite effect. We confirmed the reciprocal action of these synthetic RORα ligands on gene expression, mitochondrial mass, and uncoupled oxygen consumption rate in cultured murine and human adipocytes. Time course analysis revealed stepwise variation in gene expression, first of TLE3, an inhibitor of the thermogenic program, followed by a reciprocal effect on PRDM16 and UCP1. Finally, RORα ligands were shown to be useful tools to modulate in vivo UCP1 expression in scWAT with associated changes in this fat depot mass. SR3335 and SR1078 provoked the opposite effects on the WT mice body weight, but without any effect on sg/sg mice. This slimming effect of SR3335 was related to an increased adaptive thermogenesis of the mice, as assessed by the rectal temperature of cold-stressed mice and induction of UCP1 in scWAT, as well as by indirect calorimetry in presence or not of a ß3-adrenoceptor agonist. These data confirmed that RORα ligands could be useful tools to modulate thermogenesis and energy homeostasis.NEW & NOTEWORTHY The regulation of adipose tissue browning was not fully deciphered and required further studies explaining how the regulation of this process may be of interest for tackling obesity and related metabolic disorders. Our data confirmed the involvement of the transcription factor RORα in the regulation of nonshivering thermogenesis, and importantly, revealed the possibility to in vivo modulate its activity by synthetic ligands with beneficial consequences on fat mass and body weight of the mice.

GABA-mediated activated microglia induce neuroinflammation in the hippocampus of mice following cold exposure through the NLRP3 inflammasome and NF-κB signaling pathways.

Chronic cold stress has long-term dramatic effects on the animal immune and neuroendocrine systems. As one of the important regions of the brain, the hippocampus is the main region involved in response to stressors. Nevertheless, the impact to the hippocampus following cold exposure and the underlying mechanism involved are not clear. To evaluate the response of the hippocampus during chronic cold stress, male C57BL/6 mice were exposed to 4 °C, 3 h per day for 1 week, after which neuroinflammation and the molecular and signaling pathways in the hippocampus response to cold stress were investigated. To confirm the potential mechanism, BV2 cells were treated with γ-aminobutyric acid (GABA) and BAY 11-7082 and MCC950, then the activation of microglia and key proteins involved in the regulation of inflammation were measured. We demonstrated that chronic cold stress induced the activation of microglia, the emergence of neuroinflammation, and the impairment of neurons in the hippocampus, which might be the result of GABA-mediated activation of nod-like receptor protein 3 (NLRP3) inflammasome and the nuclear factor kappa B (NF-κB) signaling pathway.

Zinc, manganese, and copper amino acid complexes improve performance and bone characteristics of layer-type chicks under thermoneutral and cold stress conditions.

Two experiments were designed to evaluate the effect of mineral-amino acid complexes (AACM) as a partial replacement of inorganic mineral (IM) in layer-type chicks' diets. Both studies had the same dietary treatments, where in experiment 1 (Exp. 1) was conducted under thermoneutral conditions from 0 to 35 D and chicks in experiment 2 (Exp. 2) were exposed to cold stress conditions at nighttime during the first 15 D and to thermoneutral condition from 16 to 35 D. For each trial, 1,200 one-day-old Lohmann Brown chicks were used, with 20 cage replicates with 30 chicks per cage. Treatments consisted of the control diet (IM; with 70, 70, and 8 mg/kg of zinc [Zn], manganese [Mn], and copper [Cu], respectively) and the treatment diet (AACM, with 40, 40, and 2.75 mg/kg of Zn, Mn, and Cu, respectively, from IM sources, along with 30, 30, and 5.25 mg/kg of Zn, Mn, and Cu, respectively). Data were submitted to analysis of variance, and means were compared using the t-test (P < 0.05). In Exp. 1, there were no significant differences between treatments on chick performance. However, AACM-fed chicks had higher thymus (P = 0.03) and cecum weight (P < 0.01), superior micromineral deposition in the tibias (P < 0.01), and reduced phosphorus excretion (P = 0.03). In Exp. 2, chicks fed with AACM had higher body weight gain (P = 0.04), better average daily feed intake (P = 0.03), lower phosphorus excretion (P = 0.02), and higher liver and pancreas weight (P < 0.01) in the last week of the study. In conclusion, chicks fed with AACM under thermoneutral conditions had higher bone mineralization and reduced excretion of phosphorus, and in adverse conditions, AACM improves performance and liver and pancreas weight, also reducing phosphorus excretion.

Varying Atmospheric CO2 Mediates the Cold-Induced CBF-Dependent Signaling Pathway and Freezing Tolerance in Arabidopsis.

Changes in the stomatal aperture in response to CO2 levels allow plants to manage water usage, optimize CO2 uptake and adjust to environmental stimuli. The current study reports that sub-ambient CO2 up-regulated the low temperature induction of the C-repeat Binding Factor (CBF)-dependent cold signaling pathway in Arabidopsis (Arabidopsis thaliana) and the opposite occurred in response to supra-ambient CO2. Accordingly, cold induction of various downstream cold-responsive genes was modified by CO2 treatments and expression changes were either partially or fully CBF-dependent. Changes in electrolyte leakage during freezing tests were correlated with CO2's effects on CBF expression. Cold treatments were also performed on Arabidopsis mutants with altered stomatal responses to CO2, i.e., high leaf temperature 1-2 (ht1-2, CO2 hypersensitive) and ß-carbonic anhydrase 1 and 4 (ca1ca4, CO2 insensitive). The cold-induced expression of CBF and downstream CBF target genes plus freezing tolerance of ht1-2 was consistently less than that for Col-0, suggesting that HT1 is a positive modulator of cold signaling. The ca1ca4 mutant had diminished CBF expression during cold treatment but the downstream expression of cold-responsive genes was either similar to or greater than that of Col-0. This finding suggested that ßCA1/4 modulates the expression of certain cold-responsive genes in a CBF-independent manner. Stomatal conductance measurements demonstrated that low temperatures overrode low CO2-induced stomatal opening and this process was delayed in the cold tolerant mutant, ca1ca4, compared to the cold sensitive mutant, ht1-2. The similar stomatal responses were evident from freezing tolerant line, Ox-CBF, overexpression of CBF3, compared to wild-type ecotype Ws-2. Together, these results indicate that CO2 signaling in stomata and CBF-mediated cold signaling work coordinately in Arabidopsis to manage abiotic stress.

Effects of exogenous α-oxoglutarate on proline accumulation, ammonium assimilation and photosynthesis of soybean seedling (Glycine max(L.) Merr.) exposed to cold stress.

The objective of this study was to examine the effects of exogenous α-oxoglutarate on leaf proline accumulation, ammonium assimilation and photosynthesis of soybean when exposed to cold stress. To achieve this objective, exogenous α-oxoglutarate was sprayed to potted seedlings of Henong60 and Heinong48 at 0, 2.5, 5.0 and 7.5 mmol/L, identified as A0, A2.5, A5.0, and A7.5, respectively. Leaf samples were collected after cold stress of 24 h (S1 stage) and 48 h (S2 stage). The results indicated that exogenous α-oxoglutarate significantly enhanced leaf GS activity, NADP-GDH activity, glutamate content, proline content and photosynthesis of soybean seedling exposed to cold stress at S1 and S2 stages. The ammonium content in leaf was significantly decreased by exogenous α-oxoglutarate at both stages. 5.0 mmol/L of exogenous α-oxoglutarate is the optimum concentration in this study. Leaf proline content for Henong60 and Heinong48 at A5.0 was 37.53% and 17.96% higher than that at A0 at S1 stage, respectively. Proline content for Henong60 and Heinong48 increased by 28.82% and 12.41% at A5.0 and A0, respectively, at S2 stage. Those results suggested that exogenous α-oxoglutarate could alleviate the adverse effects of cold stress.

Nystose regulates the response of rice roots to cold stress via multiple signaling pathways: A comparative proteomics analysis.

Small fructans improve plant tolerance for cold stress. However, the underlying molecular mechanisms are poorly understood. Here, we have demonstrated that the small fructan tetrasaccharide nystose improves the cold stress tolerance of primary rice roots. Roots developed from seeds soaked in nystose showed lower browning rate, higher root activity, and faster growth compared to seeds soaked in water under chilling stress. Comparative proteomics analysis of nystose-treated and control roots identified a total of 497 differentially expressed proteins. GO classification and KEGG pathway analysis documented that some of the upregulated differentially expressed proteins were implicated in the regulation of serine/threonine protein phosphatase activity, abscisic acid-activated signaling, removal of superoxide radicals, and the response to oxidative stress and defense responses. Western blot analysis indicated that nystose promotes the growth of primary rice roots by increasing the level of RSOsPR10, and the cold stress-induced change in RSOsPR10levelis regulated by jasmonate, salicylic acid, and abscisic acid signaling pathways in rice roots. Furthermore, OsMKK4-dependentmitogen-activated protein kinase signaling cascades may be involved in the nystose-induced cold tolerance of primary rice roots. Together, these results indicate that nystose acts as an immunostimulator of the response to cold stress by multiple signaling pathways.

Curcumin addition in diet of laying hens under cold stress has antioxidant and antimicrobial effects and improves bird health and egg quality.

Curcumin is an herbal component with several biological properties, and we highlight here the thermal stability, antioxidant and anti-inflammatory activity. We determined whether curcumin supplementation in the diets of laying hens under cold stress and naturally infected with Escherichia coli would control infection, and would have positive effects on overall health, as well as egg production and quality. We allocated 36 chickens that had been naturally infected with E. coli into two groups, with six replicates and three chickens per repetition: control group and curcumin group (200 mg curcumin/kg). The experimental period lasted 42 days, and fecal, blood and egg samples were collected at 1, 21 and 42 days We found that feces and eggs had lower total bacterial counts, E. coli counts and total coliform counts in the curcumin group at 21 and 42 days. In fresh eggs, the brightness and yellow intensity (b+) were significantly higher in the curcumin group. In stored eggs, higher specific gravity, albumen height and lower yolk pH were observed in the curcumin group. Fresh eggs collected and stored on day 42 showed lower levels of lipid peroxidation in the curcumin group, while the total antioxidant capacity in the stored eggs was significantly higher in the curcumin group. The curcumin group showed lower total leukocyte counts as a result of lower numbers of neutrophils and lymphocytes, as well as lower levels of total protein, alkaline phosphatase and alanine aminotransferase. Lower serum lipoperoxidation at 42 days was observed in the curcumin group, probably because of the higher activity of glutathione peroxidase and glutathione transferase in other words, because of antioxidant stimulation. Taken together, our findings suggest that curcumin supplementation in laying hens under cold stress and with colibacillosis has positive effects on infection control because of antioxidant stimulation.

Transcriptome sequencing reveals the effects of cadmium toxicity on the cold tolerance of the wolf spider Pirata subpiraticus.

As the predominant predator of pests in rice fields, spiders have been exposed to cadmium (Cd) pollution for a long time. The livability of spiders during the overwintering period is closely related to population growth in spring, but the effects of Cd on spider's survival of cold hardness and the underlining mechanism remain unclear. In the present study, we found that some growth parameters (body length, width, mass and livability) in the wolf spider Pirata subpiraticus were altered distinctively under Cd stress. To investigate the effects of Cd toxicity on the spider at molecular levels, RNA-sequencing was performed on the spiderlings undergoing ambient temperature alterations. Transcriptome data showed that a total of 807 differentially expressed genes (DEGs) were yielded in the comparison. The obtained DEGs were mainly linked with metabolism-related process, including oxidoreductase activity and lipid transport, and 25 DEGs were associated with the reported cryoprotectants, including glycerol, arginine, cysteine, heat shock protein, glucose and mannose. Growth factors (insulin growth factor, platelet-derived growth factor and transforming growth factor) and cytochrome P450 encoding genes were dramatically expressed in the spider. Furthermore, transcriptional factors (TFs) family were characterized according to the transcriptomic profile, and ZBTB TFs were represented the most distinctive alterations in the characterized genes. Collectively, our study illustrated that Cd poses disadvantageous effects on the growth of P. subpiraticus at cold ambient temperature, and the spiders are capable of responding to the adverse Cd stress by expressing the genes involved in the metabolism of energy substances, cryoprotectants and immune-related components.