Genome-Wide Exploration of the Grape GLR Gene Family and Differential Responses of VvGLR3.1 and VvGLR3.2 to Low Temperature and Salt Stress

Grapes,one of the oldest tree species globally,are rich in vitamins.However,environmental conditions such as low temperature and soil salinization significantly affect grape yield and quality.The glutamate receptor(GLR)family,comprising highly conserved ligand-gated ion channels,regulates plant growth and development in response to stress.In this study,11 members of the VvGLR gene family in grapes were identified using whole-genome sequence analysis.Bioinformatic methods were employed to analyze the basic physical and chemical properties,phylogenetic trees,conserved domains,motifs,expression patterns,and evolutionary relationships.Phylogenetic and collinear analyses revealed that the VvGLRs were divided into three subgroups,showing the high conservation of the grape GLR family.These members exhibited 2 glutamate receptor binding regions(GABAb and GluR)and 3-4 transmembrane regions(M1,M2,M3,and M4).Real-time quantitative PCR analysis demonstrated the sensitivity of all VvGLRs to low temperature and salt stress.Subsequent localization studies in Nicotiana tabacum verified that VvGLR3.1 and VvGLR3.2 proteins were located on the cell membrane and cell nucleus.Additionally,yeast transformation experiments confirmed the functionality of VvGLR3.1 and VvGLR3.2 in response to low temperature and salt stress.Thesefindings highlight the significant role of the GLR family,a highly conserved group of ion channels,in enhancing grape stress resistance.This study offers new insights into the grape GLR gene family,providing fundamental knowledge for further functional analysis and breeding of stress-resistant grapevines.

Effects of Low Temperature Stress on Germination and Physiological Characteristics of Different Sweet Maize Varieties

[Objectives]The paper was to explore the effects of low temperature stress on germination and physiological characteristics of different sweet maize varieties.[Methods]Taking Taitian 264,Zhexuetian 1 and Chaotian 4 as the research objects,the changes in germination potential,germination index,plant height,biomass,and antioxidant enzyme activity of maize seeds were studied under optimal temperature conditions(25℃)and low temperature stress conditions(10℃).[Results]Under 10℃stress,the germination rate and germination index of Taitian 264 were higher than that of Zhexuetian 1 and Chaotian 4.Under low temperature stress,Taitian 264 exhibited the least reduction in height and biomass,while Zhexuetian 1 had the most reduction.Additionally,the SOD and POD activities of Taitian 264 were higher than that of Zhexuetian 1 and Chaotian 4 under both temperature conditions,while the MDA content of Taitian 264 was lower.Taitian 264 showed strong germination ability against low temperature stress.[Conclusions]This study provides a basis for timely sowing practices of sweet maize in agricultural production.

Advances in Molecular Regulatory Mechanisms of Fruit Trees under Low Temperature Stress

The most recent research findings on the tolerance of fruit trees to cold stress are reviewed from a molecular perspective,including the perception and transduction of low temperature calcium signaling,CBF-dependent molecular regulatory mechanisms,non-CBF-dependent molecular regulatory mechanisms,and so forth.The objective is to provide a reference basis for further improving the cold resistance of fruit trees and cultivating new varieties of hardy plants.

Effects of Low Temperature Stress on Physiological and Biochemical Characteristics of Podocarpus nagi

[Objective] The paper was to study the effect of low temperature stress on physiological and biochemical characteristics of Podocarpus nagi. [Method] Through the determination of physiological indices such as plasma membrane permeability, free proline content, soluble sugar content, malondialdehyde （MDA） content and chlorophyll content, the change law of these indices of P. nagi seedlings under natural conditions and artificially controlled low temperature conditions within the continuous 5 d was studied. [Result] The soluble sugar content, free proline content, MDA content and plasma membrane permeability of P. nagi seedlings were slightly in- creased compared with control; the chlorophyll content gradually decreased with the prolongation of low temperature stress. P. nagi seedlings produced active response to low temperature stress, so the low temperature injury P. nagi seedlings suffered was reduced. [Conclusion] The study provided theoretical basis for winter management in P. nagi cultivation in Hanjiang plain area.

Effect of Acute Low Temperature Stress on Oxygen Consumption Rate and Respiration Frequency in Silurus meridionalis and Pelteobag vachelli

The objective of the study was to explore the effect of acute low temperature stress on VO2 and Vf of Silurus meridionalis and Pelteobag vachelli after 10 minutes cold water bath with different temperature.The investigation was operated under the temperature of 24 ℃.It was found that the VO2 and Vf of Silurus meridionalis after 6 and 0 ℃ stress showed a decrease-increase-decrease trend while other groups showed a rapid increase then slowly recovery trend.The VO2 and Vf of Pelteobag vachelli after 0 ℃stress showed a decrease-increase-decrease trend while other groups showed an increase then slowly recovery process.It was suggested that Pelteobag vachelli was more adaptive to acute cold stress,but it cost more energy adapting to cold stress compared to Silurus meridionalis.

De Novo Transcriptome Analysis in Hevea brasiliensis to Unveil Genes Involved in Low Temperature Stress Response

Low temperature is one of the adversities threatening the growth and development and reduces the yield of rubber trees.However,molecular mechanisms toward rubber trees in response to low temperature are largely unclear.In this study,7,159 and 7,600 differentially expressed genes(DEGs)were identified in‘Reyan 73397’rubber trees.Through GO analysis,the catalytic activity was the representative of the GO term in the only DEGs at the two studied temperatures(room temperature and 4°C,respectively),while KEGG analysis showed that carbon metabolism was the most important grouping under the comparison of these two temperatures.In addition,expression of 9 members of transcription factor MYB family genes were further verified by qRT-PCR,and MYB family genes may play important roles in the regulation of rubber trees under low temperature stress.This study provided a theoretical foundation for(1)revealing the molecular mechanisms of rubber trees in response to low temperature and(2)breeding of tolerant varieties of rubber trees.

Analysis of microRNA Expression Characteristics Related to Low Temperature Stress in Chewing Cane

[Objectives]To explore microRNA expression characteristics related to low temperature stress in chewing cane.[Methods]The research on miRNA under abiotic stress of sugarcane at home and abroad mainly focused on the types and regulation of miRNA under cold,heat,drought,high salt,and mechanical stress.However,there are few studies on miRNA under low temperature stress in chewing cane.The target genes of miR394 and miR825 in chewing cane were predicted and functionally analyzed by bioinformatics technology.[Results]The results showed that the target genes of miR394 and miR825 were mainly members of the WRKY transcription factor family,involved in plant growth,development and stress resistance.Real-time fluorescence quantitative PCR analyzed the expression characteristics of target miRNA in different tissues of chewing cane at different periods of low temperature stress.[Conclusions]The results showed that the expression of chewing cane miR394 and miR408 had temporal and spatial specificity and tissue specificity,both of which could respond to low temperature stress with significant differential expression.

Gene Expression and Activities of SOD in Cucumber Seedlings Were Related with Concentrations of Mn^(2+),Cu^(2+),or Zn^(2+) Under Low Temperature Stress

Effects of increasing Mn^2＋, Cu^2＋, or Zn^2＋ on SOD expressions were studied in cucumber seedlings under low temperature stress. Both gene expressions and activities of Cu/Zn-SOD and Mn-SOD in cucumber seedling leaves were induced by increasing Mn^2＋, Cu^2＋, or Zn^2＋ under low temperature stress, especially 48 h afterwards. The activities of Cu/Zn-SOD and Mn-SOD at 0 and 48 h after treatment were in accordance with their gene expression levels, which implied that the transcriptional regulation plays key roles in regulating their activities at the early stage of low temperature stress. Gene expressions of Cu/Zn-SOD and Mn-SOD declined at 96 h, but Cu/Zn-SOD and Mn-SOD activities still remain high, which suggested that Cu/Zn-SOD and Mn-SOD activities might be regulated by other factors after transcription at the later stage of low temperature stress. Therefore, we concluded that the increasing Mn^2＋, Cu^2＋, or Zn^2＋ could increase the capacity of scavenging ROS in cucumber seedlings under low temperature stress by inducing gene expressions of Cu/ Zn-SOD and Mn-SOD, elevating activities of Cu/Zn-SOD, Mn-SOD, or regulating other factors after transcription.

Low temperature stress on the hematological parameters and HSP gene expression in the turbot Scophthalmus maximus

To study the effect of low temperature stress on hematological parameters and HSP gene expression in the turbot （Seophthalmus maximus）, water temperature was lowered rapidly from 18 to 1℃. During the cooling process, three individuals were removed from culture tanks at 18, 13, 8, 5, 3, and 1℃. Blood samples and tissues were taken from each individual, hematological indices and HSP gene expression in tissues were measured. The red blood cell count, white blood cell count, and hemoglobin concentration decreased significantly （P〈0.05） as temperature decreased. Enzyme activities of plasma alanine transaminase and creatine kinase increased as temperature decreased, whereas aspartic transaminase and γ-glutamyl transpeptidase activities displayed no obvious changes above 1℃ and lactate dehydrogenase activity increased first and then decreased. Blood urea nitrogen and uric acid levels were highest at 8℃, and creatinine concentration was highest at 3℃. The concentrations of plasma cortisol, cholesterol, and triglyceride all increased significantly （P〈0.05） as temperature decreased. The serum glucose concentration increased first and then decreased to the initial level. The HSP70 mRNA expression showed various patterns in different tissues, whereas HSP90 mRNA expression showed the same tendency in all tissues. Overall, these results indicate that temperature decreases in the range of 8 to 5℃ may induce a stress response in S. maximus and that temperature should be kept above 8℃ in the aquaculture setting to avoid damage to the fish.

Microstructure and residual stress of TiN films deposited at low temperature by arc ion plating

The TiN films were deposited on 316 L stainless steel substrates at low temperature by arc ion plating. The influences of substrate bias voltage and temperature on microstructure, residual stress and mechanical properties of the films were investigated by EDS, SEM, XRD and nanoindenter tester, respectively. The results showed that the TiN films were highly oriented in（111） orientation with a face-centered cubic structure. With the increase of substrate bias voltage and temperature, the diffraction peak intensity increased sharply with simultaneous peak narrowing, and the small grain sizes increased from 6.2 to 13.8 nm. As the substrate temperature increased from 10 to 300℃, the residual compressive stress decreased sharply from 10.2 to 7.7 GPa, which caused the hardness to decrease from 33.1 to 30.6 GPa, while the adhesion strength increased sharply from 9.6 to 21 N.

Effects of Phosphate Fertilizer on Cold Tolerance and Its Related Physiological Parameters in Rice Under Low Temperature Stress

The study was designated to explore the physiological mechanism of cold tolerance enhanced by phosphate in rice. An experiment was conducted to investigate the effects of different levels of phosphate fertilizer on cold tolerance and its related physiological parameters in rice seedings （chilling-sensitive cv. Changbai 9 and chilling-tolerant cv. Jijing 81） under low temperature stress. At the same time, the identification of cold tolerance was conducted. Compared with the normal temperature treatment, the relative chlorophyll content, photosynthesis rate, Fv/Fm and qP decreased and index of unsaturated fatty acid increased in rice under low temperature stress. The effect of chilling-sensitive cultivars was more than that of chilling-tolerant cultivars, more phosphorus fertilizer properly improved seedling quality of rice, slowed relative chlorophyll content dropping degree of rice seeding, increased photosynthesis rate, Fv/Fm, qP and index of unsaturated fatty acids, and enhanced the ability to chilling-tolerant cultivars under low temperature. The effect on chilling-tolerant cultivars was significantly higher than that on chilling sensitive cultivars by applying more phosphorus fertilizer. Phosphate regulated photosynthetic physiology and membrane fluidity to reduce injury by low temperature, and increasd the cold tolerance capacity of rice.

Evaluation of Rice Seedling Tolerance to Constant and Intermittent Low Temperature Stress

M202, IR50 and advanced backcross （BC4F6） lines carrying the cold tolerance QTLs qCTS4 and qCTS12 were evaluated using three low temperature stress assays （constant, intermittent and constant with recovery period）. Under constant stress, two BC4F6 lines （MIb 4853-9 and MIb 6885-2） exhibited differences in seedling growth and accumulation of stress-related compounds although both carry the two QTLs in the IRS0 background. Differences between these lines were also observed in the constant with recovery period assay, although both of them performed comparably under intermittent stress, MIb 6885-2 performed more similarly to M202 in the constant and constant with recovery period assays, suggesting that this line contains an introgressed region（s） not present in MIb 4853-9. The three assays were also applied to assess variations in cold tolerance in a set of diverse germplasms. Performance metrics and visual ratings were comparable for evaluating tolerance to constant stress. However, differences in response to intermittent stress were more evident from growth and total chlorophyll measurements than from visual ratings. With regard to the constant with recovery period assay, about 15% of the germplasm accessions did not recover. However, some lines which exhibited chilling injuries of comparable severity were able to overcome them. This recovery phenotype may improve rice performance in the field and warrant further investigation.

Effect of Low Temperature Stress on Sweet Potato S-Adenosyl Methionine Synthetase Gene Expression

[Objective] The mRNA expression level changes of S-adenosylmethionine synthetase （SAMS） under low temperature stress was studied. [Method] Total RNA were extracted from leaves, stem and earthnut of sweet potato 0,12,24,48 and 72 h after low temperature treatement, mRNA expression level was analyzed by reverse expression and Real-time PCR technique. [Result] The expression quality of the gene extracted from leaves, stem and earthnut increased and the expression quality reached the peak point 24,72 and 72 h after low temperature treatment respectively. The expression change of earthnut was the biggest. [Conclusion] Low temperature was good for increasing mRNA expression of relevart genes.

Effect of Low Temperature Stress on Protein Content of Toona Sinensis Seedlings and Expression of Specific Protein

[Objective] The paper was to study the changes of protein content and component in leaves of Toona Sinensis under low-temperature stress.[Method] Potted experiment was adopted,and SDS-PAGE electrophoresis was also used to analyze the dynamic changes of protein in T.Sinensis leaves.[Result] Low temperature stress could change the content and component in leaves of T.Sinensis,but different provenances had different performance under different temperatures,so did the same provenance under different stress periods.SDS-PAGE electrophoresis results indicated that the change law of provenances of Xixia of Henan and Nanjing of Jiangsu with stronger cold resistance was similar,showing the change trend of "increase-decrease-increase".Protein was greatly expressed after stress for 1 d,the color of band became darker;the content gradually decreased in the following second and third day,and the color of bands was lighter;the content began to increase at the forth day.Two provenances induced the specific proteins with molecular weights of 27.6 and 22.5 kD,respectively.The soluble protein content of provenance of Xiapu of Fujian with relatively weak cold resistance was gradually increased,but no new protein bands were induced.The changes of protein band color of various provenances in SDS-PAGE electrophoresis was basically consistent with the changes of protein content,the provenance with stronger cold resistance could induce the production of specific proteins.[Conclusion] The study provided theoretical basis for under the molecular mechanism of plant cold resistance,which had great significance in theory and practice.

Physiological Responses of Actinidia arguta (Seib.et.Zucc.) to Low Temperature Stress

[Objective] To study the ecophysiological effects of low temperature stress on Actinidia arguta （Seib.et.Zucc.）, and provide a theoretical basis for the introduc- tion and breeding of cold resistant varieties. [Method] A. arguta as the test material was processed at room temperature of 4 ℃ to determine the contents of chloro- phyll, water soluble sugar, water soluble protein, free proline, MDA, and antioxidant enzymes （POD activity, SOD activity, CAT activity） with the treatment at 25℃ as the control. [Results] The results indicated that with the prolonging of stress time, the content of chlorophyll was first increased and then decreased, and the content of MDA was increased; soluble sugar content of seedling leaf decreased gradually, while the soluble protein and proline content of seedling leaves were first increased and then decreased; the activities of SOD and POD were displayed a decline trend, meanwhile the activities of CAT was first increased and then decreased. [Conclu- sion] The various indicators showed that under low temperature stress, the chloro- phyll content decreased accompanied with membrane lipid peroxidation and MDA accumulation, and soluble sugar, soluble protein, free proline and antioxidant en- zymes play a protective role in different degrees.

Physiological Response and Transcriptome Analysis of Cotton Leaves under Low Temperature Stress at the Two-leaf Stage

[Objectives]To investigate the effect of low temperature treatment on cotton leaves at the two-leaf stage.[Methods]Two cotton varieties(CN01 and SJB016(low temperature-tolerant))were used as the trial materials.They were treated at 25(CK)and 12℃(low temperature)for 0,3,6,12,24,48 and 72 h,respectively.Then,the changes in the contents of MDA,SS and Pro in the cotton leaves were analyzed.Based on the analysis results,RNA-seq verification was performed.[Results]Two cotton varieties(CN01 and SJB016(low temperature-tolerant))were used as the trial materials.They were treated at 25(CK)and 12℃(low temperature)for 0,3,6,12,24,48 and 72 h,respectively.Then,the changes in the contents of MDA,SS and Pro in the cotton leaves were analyzed.Based on the analysis results,RNA-seq verification was performed.[Conclusions]These genes may play an important role in improving the cold resistance of cotton.

Effect of heat treatment on microstructure and mechanical properties of Ti-containing low alloy martensitic wear-resistant steel

Effects of quenching temperature and cooling conditions(water cooling and 10%NaCl cooling)on microstructure and mechanical properties of a 0.2%Ti low alloy martensitic wear-resistant steel used for die casting ejector plate were investigated.The results show that lath martensite can be obtained after austenitizing in the range of 860-980℃and then water cooling.With an increase in austenitizing temperature,the precipitate content gradually decreases.The precipitates are mainly composed of TiC and Ti4C2S2,and their total content is between 1.15wt.%and 1.64wt.%.The precipitate phase concentration by water-cooling is higher than that by10%NaCl cooling due to the lower cooling rate of water cooling.As the austeniting temperature increases,the hardness and tensile strength of both water cooled and 10%NaCl cooled steels firstly increase and then decrease.The experimental steel exhibits the best comprehensive mechanical properties after being austenitized at 900℃,cooled by 10%NaCl,and then tempered at 200℃.Its hardness,ultimate tensile strength,and wear rate reach551.4 HBW,1,438.2 MPa,and 0.48×10^(-2)mg·m^(-1),respectively.

Changes in Physiological Indexes of SPDS Transgenic Potato Plants under Low Temperature Stress

Using potato plants overexpressing spermidine synthase（SPDS） gene as experimental materials, changes in chlorophyll content, malondialdehyde（MDA） content and superoxide dismutase（SOD） activity of potato leaves under low temperature stress were determined. According to the results, chlorophyll content of experimental plants showed a decreasing trend; MDA content of 01-47 was significantly higher than that of Atlantic; MDA content of 01-6 and 01-49 was significantly lower than that of Atlantic; SOD activity of 01-6 and 01-47 was higher than that of Atlantic. Potato lines 01-6 and 01-47 can be further cultivated to breed new cold-resistant potato varieties.

Regulation of Calcium on Peanut Photosynthesis Under Low Night Temperature Stress

The effects of different levels of CaCl 2 on photosynthesis under low night temperature（8°C） stress in peanuts were studied in order to find out the appropriate concentration of Ca2＋through the artificial climate chamber potted culture test.The results indicated that Ca2＋,by means of improving the stomatal conductivity of peanut leaves under low night temperature stress,may mitigate the decline of photosynthetic rate in the peanut leaves.The regulation with 15 mmol L-1CaCl 2（Ca15） was the most effective,compared with other treatments.Subsequently,the improvement of Ca2＋on peanut photosynthesis under low night temperature stress was validated further through spraying with Ca15,Ca2＋chelator（ethylene glycol bis（2-aminoethyl） tetraacetic acid; EGTA） and calmodulin antagonists（trifluonerazine; TFP）.And CaM（Ca2＋-modulin） played an important role in the nutritional signal transduction for Ca2＋mitigating photosynthesis limitations in peanuts under low night temperature stress.

Postharvest Low Temperature Conditioning Reduces Peel Browning and Improves Fruit Quality in Storage and Subsequent Shelf Life of Huangguan Pear

Huangguan pear (Pyrus bretschneideri Rehd cv. Huangguan) is a pear cultivar that rapidly developed in China. However, rapid postharvest browning appearing in fruit peel and core during storage and shelf life pose a challenge for their marketing. The potential for low temperature conditioning (LTC) treatment to inhibit peel browning and improve quality of Huangguan pears in storage and shelf life was investigated. Pears were treated at 8℃ - 9℃ for 1, 3, 6 and 9 d, respectively, physiological indexes, including peel and core browning, core breakdown, malondialdehyde (MDA) content and ethanol content were determined and quality in storage period and shelf life was evaluated in this paper. LTC treatment alleviated peel browning and core browning either in storage or shelf life remarkably;it also delayed the decline of firmness, total soluble solids and titratable acidity in storage to some extent, inhibited ethanol and MDA content both in storage and shelf life effectively and maintained juiciness and crispness of pear fruit in shelf life. These results showed that LTC can serve as an important tool for the regulation of Huangguan pears external and internal quality in storage and shelf life with economic benefits and LTC treatment for 6 d was the optimum condition in the present study.