Level Of Cold Resistance Research Articles

Features of the formation of structure and mechanical properties in rolled products of various thicknesses from low-carbon microalloyed steel produced by casting and rolling complex

The article considers results of the study of microstructure parameters effect on the impact strength in temperature range from 0 to –80 °C in 20 °C increments of Charpy samples with a sharp stress concentrator and Mesnager test pieces with a circular stress concentrator from rolled coils of low-carbon microalloyed steel with various thicknesses. The used roll products were produced in conditions of JSC “Vyksa Metallurgical Plant”. The tests were performed using optical and scanning electron microscopy. It is shown that with the same chemical composition and thermomechanical treatment modes, the metal of smaller thickness (6, 8 mm) is characterized by higher strength properties (on average, by 10 MPa for temporary resistance, by 30 MPa for yield strength) and a margin for viscous properties at negative temperatures at close values of grain score and average grain size corresponding to 10 – 11 numbers according to the State standard GOST 5639. The metal with a thickness of 12 mm has the lowest level of cold resistance, and the temperature of brittle transition is minus 50 °C. Structure of rolled products of various thicknesses has a variation in grain size. Rolled metal of smaller thicknesses have a smaller grains corresponding to number 14, rolled metal of larger thicknesses has a larger grains corresponding to number 8. By conducting electron microscopic studies using the backscattered electron method, it was found that a greater number of large-angle boundaries, which are barriers for brittle cracks propagation, are observed in the 6, 8 mm thick rolled products. The constructed orientation maps of the microstructure showed the presence of pronounced deformation texture corresponding to the orientations <110>||RD (rolling direction) and (<113>...<112>)||RD for rolled products with a thickness of 6 mm.

Comprehensive Proteome and Lysine Acetylome Analysis Reveals the Widespread Involvement of Acetylation in Cold Resistance of Pepper (Capsicum annuum L.).

Pepper is a typical warmth-loving vegetable that lacks a cold acclimation mechanism and is sensitive to cold stress. Lysine acetylation plays an important role in diverse cellular processes, but limited knowledge is available regarding acetylation modifications in the resistance of pepper plants to cold stress. In this study, the proteome and acetylome of two pepper varieties with different levels of cold resistance were investigated by subjecting them to cold treatments of varying durations followed by recovery periods. In total, 6,213 proteins and 4,574 lysine acetylation sites were identified, and this resulted in the discovery of 3,008 differentially expressed proteins and 768 differentially expressed acetylated proteins. A total of 1,988 proteins were identified in both the proteome and acetylome, and the functional differences in these co-identified proteins were elucidated through GO enrichment. KEGG analysis showed that 397 identified acetylated proteins were involved in 93 different metabolic pathways. The dynamic changes in the acetylated proteins in photosynthesis and the “carbon fixation in the photosynthetic organisms” pathway in pepper under low-temperature stress were further analyzed. It was found that acetylation of the PsbO and PsbR proteins in photosystem II and the PsaN protein in photosystem I could regulate the response of pepper leaves to cold stress. The acetylation levels of key carbon assimilation enzymes, such as ribulose bisphosphate carboxylase, fructose-1,6-bisphosphatase, sedoheptulose-1,7-bisphosphatase, glyceraldehyde 3-phosphate dehydrogenase, phosphoribulokinase, and triosephosphate isomerase decreased, leading to decreases in carbon assimilation capacity and photosynthetic efficiency, reducing the cold tolerance of pepper leaves. This study is the first to identify the acetylome in pepper, and it greatly expands the catalog of lysine acetylation substrates and sites in Solanaceae crops, providing new insights for posttranslational modification studies.

Developmental and adult acclimation impact cold and drought survival of invasive tropical Drosophila kikkawai.

ABSTRACTNarrow distribution patterns of tropical Drosophila species are limited by lower resistance to cold or drought. In the invasive tropical Drosophila kikkawai, we tested whether developmental and adult acclimations at cooler temperatures could enhance its stress resistance level. Adult acclimation of winter collected body color morphs revealed a significant increase in the level of cold resistance. For light morph, its abundance during winter is not consistent with thermal-melanism hypothesis. However, higher cold acclimation capacity, as well as storage of energy metabolites could support its winter survival. In the wild-caught light and intermediate morphs, there is a lack of trade-off between cold and heat resistance but not in the case of dark morph. Developmental plasticity (15°C) resulted in the fivefold increase of cold survival at 0°C; and a twofold increase in desiccation resistance but a modest reduction (∼28–35%) in heat resistance as compared to morph strains reared at 25°C. Drought acclimation changes were significantly higher as compared with cold or heat pretreatment. We observed a trade-off between basal resistance and acclimation capacity for cold, heat, or drought resistance. For homeostatic energy balance, adult acclimation responses (cold versus drought; heat versus drought) caused compensatory plastic changes in the levels of proline or trehalose (shared patterns) but different patterns for total body lipids. In contrast, rapid cold or heat hardening-induced changes in energy metabolites were different as compared to acclimation. The ability of D. kikkawai to significantly increase stress tolerance through plasticity is likely to support its invasion potential.

Trehalose can alleviate decreases in grain number per spike caused by low‐temperature stress at the booting stage by promoting floret fertility in wheat

AbstractAlleviating the negative effects of low temperature at the booting stage on wheat grain number and yield is important for maintaining high and stable wheat yields. In this study, we selected wheat varieties with different levels of cold resistance, simulated low temperature at the booting stage and exogenously applied trehalose to study its effect on wheat floret development under low‐temperature stress and explore the physiological mechanism of that process. The results showed that higher levels of endogenous trehalose benefited wheat resistance to low‐temperature stress. Exogenous trehalose inhibited floret degeneration and increased floret fertility in the apical spikelets, thus significantly alleviating the decrease in grain number per spike caused by low temperature. The results of the metabolomics analysis as well as the physiological indexes showed that trehalose significantly promoted the assimilation of nitrogen in florets under low‐temperature stress, thus reducing the accumulation of ammonium ions in the plant cells. In addition, exogenous trehalose significantly increased the endogenous spermidine level in florets, increased their glutathione and ascorbic acid contents, promoted the glutathione‐ascorbic acid cycle, and thereby reduced the contents of reactive oxygen species in florets. This may be an important physiological mechanism by which trehalose alleviates the effect of low‐temperature stress on floret development in wheat.

Transcriptional regulation of bark freezing tolerance in apple (Malus domestica Borkh.)

Freezing tolerance is a significant trait in plants that grow in cold environments and survive through the winter. Apple (Malus domestica Borkh.) is a cold-tolerant fruit tree, and the cold tolerance of its bark is important for its survival at low temperatures. However, little is known about the gene activity related to its freezing tolerance. To better understand the gene expression and regulation properties of freezing tolerance in dormant apple trees, we analyzed the transcriptomic divergences in the bark from 1-year-old branches of two apple cultivars, “Golden Delicious” (G) and “Jinhong” (H), which have different levels of cold resistance, under chilling and freezing treatments. “H” can safely overwinter below −30 °C in extremely low-temperature regions, whereas “G” experiences severe freezing damage and death in similar environments. Based on 28 bark transcriptomes (from the epidermis, phloem, and cambium) from 1-year-old branches under seven temperature treatments (from 4 to −29 °C), we identified 4173 and 7734 differentially expressed genes (DEGs) in “G” and “H”, respectively, between the chilling and freezing treatments. A gene coexpression network was constructed according to this expression information using weighted gene correlation network analysis (WGCNA), and seven biologically meaningful coexpression modules were identified from the network. The expression profiles of the genes from these modules suggested the gene regulatory pathways that are responsible for the chilling and freezing stress responses of “G” and/or “H.” Module 7 was probably related to freezing acclimation and freezing damage in “H” at the lower temperatures. This module contained more interconnected hub transcription factors (TFs) and cold-responsive genes (CORs). Modules 6 and 7 contained C-repeat binding factor (CBF) TFs, and many CBF-dependent homologs were identified as hub genes. We also found that some hub TFs had higher intramodular connectivity (KME) and gene significance (GS) than CBFs. Specifically, most hub TFs in modules 6 and 7 were activated at the beginning of the early freezing stress phase and maintained upregulated expression during the whole freezing stress period in “G” and “H”. The upregulation of DEGs related to methionine and carbohydrate biosynthetic processes in “H” under more severe freezing stress supported the maintenance of homeostasis in the cellular membrane. This study improves our understanding of the transcriptional regulation patterns underlying freezing tolerance in the bark of apple branches.

Cold resistance of modern soya cultivars while germinating seeds under the conditions of low positive temperatures

The aim and tasksof the study foresaw the estimation of modern soya cultivars from plant breeding institutions of Ukraine on cold resistance during the period of seeds germination and singling out the resistant genotypes to low temperatures at the stage of germination for including them in plant breeding programs as the initial material and creation of adaptive cultivars to cold.Material and methods.The research was carried out during 2014–2016 years in the laboratory of plant immunity to diseases and pests at the Institute of plant growing named after V.Ya.Yuriev of NAAS. The material for the research was represented by 34 soya cultivars from plant breeding institutions of Ukraine. Cold resistance was determined by the quality of germinated seeds underlow positive temperatures (+10 ºC ) and the percent was calculated from the quantity of tested germinated seeds in the optimum conditions for the crop (+24 ºC).Results and discussion.Soya cultivars involved in test were grown in the research rotation of the plant growing Institute named after V.Ya.Yuriev of NAAS. The weather conditions during the period of soya vegetation by years of study were characterized as optimum in 2014 and 2016 years(HTC=1.14 and 1.32) and arid in 2015 year(HTC=0,6).The results of seeds germination of all soya cultivars in laboratory under the temperature of +10 ºC showed differences between cultivars as to their cold resistance. That allowed to divide them into groups. The group of weak cold resistant cultivars (21–40 %) includes 6 plant breeding elaborations – Pyssanka, Farvater, Russa, Vil’shanka, Sharm, Vezha. The group of cultivars with average cold resistance(41–60 %) comprises 14 cultivars (Bajka, Sprytna, Kobza, Victoryna, Rajduga, Perlyna, Vyshyvanka, Denni, Gali, Rapssodia, Khvylya, Diademma, Khutoryanochka, Knyazhna and Romashka). The group of cultivars with cold resistance higher than average(61–80 %) includes 7 cultivars: Estafeta, Mal’vina, Symphonia, Suzirja, Triada, Zolushka, Mel’pomena. The group of high cold resistant cultivars is represented by 6 cultivars: Podyaka, Krassunya, Siverka, Syajvo, Zlata, Fejeriya.Conclusions.According to the resultsof studying 34 cultivars created in the leading plant breeding institutions 3 cultivars were singled out during 3 years (Melpomena, Podyaka, Syajvo). Among them there are one with higher than average cold resistance (Mel’ponela, 76,6 %) and two with high (Podyaka and Syajvo,89,7 and 91,9 accordingly). Cultivars Zlata, Siverka and Fejeriya are characterized by high level of cold resistance and high crop productivity. Zlata cultivar with the level of cold resistance 87,7% gave the crop productivity higher than conventional standard by 116,6%, Siverka – by 117,7%(the level of cold resistance is 82,6%), the crop productivity of cultivar Fejeriya was higher from conventional standard by 104,9% (the level of cold resistance is 82,7%). The represented cultivars with high and average cold resistance are valuable initial material for soya plant breeding for given trait and are suitable for early terms of sowing

Morphogenesis and Physiological Basis in Wheat Cultivars with Different Levels of Cold-Resistance during Cold Acclimation and Freezing Period

"Dongnong dongmai 1" is the released cultivar of winter wheat (Triticum aestivum L.) in Heilongjiang province in China. However, the physiological metabolism in the over-wintering process of the cultivar is unclear. In this study, the plant morphological characters were investigated and several physiological parameters were measured with comparisons of three winter wheat cultivars, Dongnong Dongmai 1 (cold tolerant), Dongnong 705 (semitolerant to coldness), and Jimai 22 (cold susceptible), the objective was to understand the physiological adaptation to low temperature of Dongnong Dongmai 1. The numbers of leaf, tiller, and tiller leaf as well as water content in plant were investigated from 3 Oct. to 8 Nov. at a 5 d interval. Leaf, sheath, and tiller nod were sampled from 22 Oct. to 22 Dec. at a 10 d interval. The numbers of tiller and tiller leaf were significantly higher in Dongnong Dongmai 1 than in other cultivars before frozen period. Under cold stress, water content decreased in all parts of culti- vars. Dongnong Dongmai 1 had the largest reduction of water content in leaf, but the water content in tiller nod declined slower and maintained the highest level among the three cultivars. In contrast, Jimai 22 had relatively higher water content in leaf and sharp reduction in tiller nod. The electric conductivity measurement indicated that leaves died at 30, 20, and 0 d after the frozen day in Dongnong Dongmai 1, Dongnong 705, and Jimai 22, respectively. The total soluble sugar content in leaves and leaf sheathes was the highest in Dongnong Dongmai 1, and the lowest in Jimai 22. Similarly, during frozen period, the content of total soluble sugar in tiller nod was the highest in Dongnong Dongmai 1 and the lowest in Jimai 22. Superoxide dismutase (SOD) in leaf was inactivated at 20 d after the frozen day in Dongnong 705 and Jimai 22, but maintained the certain activity even at 40 d after the frozen day in Dongnong Dongmai 1. Moreover, the activities of SOD in all parts of Jimai 22 were lower than those of other cultivars. During frozen period the activities of peroxidase (POD) were higher in sheath and tiller nod in Dongnong Dong-mai 1, it was higher in tiller nod and lower in leaf sheath in Dongnong 705, and cignificantly lower both in sheath and tiller nod in Jimai 22.The results suggest that high resistance to coldness in Dongdong Dongmai 1 is probably related to the translocation of total soluble sugar from leaf to sheath and tiller nod. Low water content in plant and relative high activities of SOD and POD in sheath and tiller nod are also contributed to the cold-resistance of Dongnong Dongmai 1.

Determination of the cold tolerance off sour cherry cultivars with frost treatments in climatic chamber

Nowadays, sour cherry buds can be seriously damaged by spring and winter frosts. Unlike other fruit species threatened by high frost damage, sour cherry cultivars have not been assessed for frost tolerance. The aim of .our survey was to establish the relative cold tolerance of the Hungarian cultivars after treatment in a climatic chamber, and to optimize the methodology formerly elaborated for the frost treatment of apricot. Fourteen cultivars of Hungarian sour cherry (Prunus cerasus) were used in the experiments, which spanned the winters of 2005/2006 and 2006/2007. Our data were used to rank cultivars in two groups according to their levels of cold resistance. We also recommend critical temperatures and treatment times for the testing of sour cherry cultivar resistance to cold in climatic chambers.

Differential gene expression in cucumber plants in response to brief daily cold treatments

The mechanisms of plant responses to short-term cold treatments applied daily in the period of active growth remain unknown. Cucumber ( Cucumis sativus L.) plants were subjected to brief drops of temper- ature (2 h, 12°C ) at the end of each night over a 6-day period (DROP treatment) and to prolonged (6 days) cool- ing at 12°C (permanent low-temperature treatment, PLT). The plants exposed to cold treatments and control plants grown at 20°C were compared in terms of cold resistance and changes in gene expression. Cold resis- tance of plants was determined on the basis of LT 50 temperature. The response of cucumber genetic machinery was assessed by means of a differential display method based on polymerase chain reaction (PCR). The changes in mRNA pool in cells of cucumber plants subjected to permanent and periodic chilling were assessed after comparing the populations of PCR fragments of cDNA. In both types of chilling protocols, the cold resistance started to increase from the 2nd day of low temperature treatment. At the end of the experiment (on the 6th day), the increment in cold resistance was three times larger for DROP compared to PLT treatment. Analysis of mRNA pool showed that the numbers of amplified fragments were nearly identical in both types of low-tem- perature treatment. The higher level of cold resistance under DROP conditions was assumed to depend on fea- tures of metabolism.

Temperature Drop as a Tool for Cold Tolerance Increment in Plants

The experiments were conducted with Cucumis sativus L., Triticum aestivum L., Brassica capitata, Solanum tuberosum, Zea mays L. and Pisum sativum L. Temperature drop increased cold resistance in all studied species. Level of cold resistance under the drop treatments was much higher than under the constant low temperature. It remained at a higher level for a longer period during de-acclimation. It is concluded that DROP technology is a good way for successful transplantation of greenhouse agricultural and bedding plants in early spring.

Changes in water status in peach buds on induction, development and release from dormancy

Peach shoots collected prior to onset of chilling in early November from mid Georgia, were exposed to short days or cold temperature to induce dormancy. A gradual increase in bound water under both conditions was found in comparison to control left under warm long days condition. To release dormancy, buds were exposed to 0 or 4°C, temperature that break dormancy, and to a 6–24°C, diurnally cycled treatment that prevents chilling accumulation, and is inefficient in breaking dormancy. Chilling temperatures (0 and 4°C) induced somewhat freer water after 39 days than the 6–24°C treatment. The proportion of free water increased until 55 days. When shoots were transferred to forcing conditions, a further rapid increase in free water was noted especially with shoots that were exposed to chilling previously. The conversion of bound to free water on exposure to forcing conditions was also verified with orchard-chilled peach buds. Buds on branches that were not exposed to effective chilling were also showing the appearance of free water after exposure to high temperatures for a long duration. Evaluating these data raises the possibility that bound water in buds of temperate fruit trees is correlated with the level of cold resistance rather than with the level of endo-dormancy. This may explain the much higher levels of freer water during dormancy in the less cold-resistant peach than in the more cold-resistant apple.