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Plant basic helix-loop-helix (bHLH) transcription factors (TFs) play central roles in various abiotic stresses. However, its role in plant cold resistance is largely unknown. Previously, we characterised CaNAC035 in pepper, which positively regulates tolerance to cold, salt and drought stresses tolerance. Here, we identified CabHLH035, a CaNAC035-interacting protein in pepper. To explore its functions in cold stress tolerance, we silenced the gene in pepper via virus-induced gene silencing (VIGS) and overexpressed the gene in Arabidopsis. The results showed that CabHLH035 expression was induced by cold treatment, and silencing of CabHLH035 decreased cold stress tolerance. Conversely, overexpression of CabHLH035 in Arabidopsis increased cold stress tolerance. To investigate homologs genes of C-repeat binding factor (CBF) pathway proteins and reactive oxygen species (ROS) marker gene expression blocking by CabHLH035, we performed yeast one-hybrid (Y1H), dual luciferase and electrophoretic mobility shift assay experiments. The results showed that CabHLH035 bound to the region upstream of the CaCBF1A and CaAPX promoters. Additionally, CaCBF1A bound to the CaDHN4 promoter. Taken together, our results showed that CabHLH035 plays a crucial role in cold stress tolerance and its potential as a target for breeding cold-resistant crops. The findings provide a basis for studying the functions and regulatory network of cold stress tolerance in pepper. [ABSTRACT FROM AUTHOR]

Polyploidization is hypothesized to improve the freezing resistance of plants in cold regions. However, adaptive strategies and key physiological mechanisms involved in the freezing resistant ability of polyploids remain unclear. In Actinidia chinensis (kiwifruits), the tetraploids and hexaploids occupy higher altitude habitats with colder climates than the diploids, providing a study system to investigate mechanisms responsible for differentiation in freezing resistance between cytotypes. We characterized environmental conditions of their natural distribution areas, and measured leaf‐level traits of cold damages and water relations at typical sites of each cytotype along an altitudinal gradient. Polyploids showed lower semi‐lethal temperature (LT50) than ice nucleation temperature (INT), reflecting a tolerance strategy to cope with freezing events in the plateau regions. More negative turgor loss points and larger cell elastic modulus of polyploids could help to alleviate damages from freezing‐induced cell dehydration, thus strengthening their tolerance to lower subzero temperatures (lower LT50). The increased supercooling capacity of polyploids (lower INT) might correlate with less extracellular ice formation due to lower osmotic potential at full turgor, apoplastic water fraction and tissue capacitance. Our study uncovers a greater cold tolerance in polyploid kiwifruits than diploids, and suggests the potential linkage between freezing tolerance and water relations. Taken together, such a divergence in stress resistance may underlie the niche shift of polyploid plants towards harsh environments. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

It is well-known that freezing affects crop growth worldwide and significantly reduces crop production in the affected regions. The study objective was to investigate the effect of sodium silicate and sodium selenite individually or in combination on Alcea rosea plants grown under cold temperature stress. In this work, hollyhock plants were grown with sodium selenite and sodium silicate to 1/2 Hoagland solution, including 1) control, 1 mM sodium sulfate, 2) 1 mM sodium silicate 3), 0.03 mM sodium selenite, 4) 1 mM sodium silicate + 0.03 mM sodium selenite and exposed to nonfreezing (20 °C) and freezing temperature (−4 °C). Nutritional elements, photosynthesis parameters, electrolyte leakage, malondialdehyde, water content, osmolytes, and antioxidant enzymes were determined. The application of Si + Se effectively enhanced the Si and Se content of leaves (54% and 164%) compared to control plants. The combined Si and Se addition increased phenols, water-soluble sugars, proline, chlorophyll, net photosynthesis (Pn), and stomatal size under cold stress. Moreover, Si and Se in combination in stressed plants inhibited electrolyte leakage and malondialdehyde (MDA) by increasing the activities of enzymes such as superoxidase dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT). The maximal to minimal values of essential oil content, relative water content (RWC), and stomatal density depended on the treatment: Si + Se > Si = Se. By increasing K content, phenol, proline, and water-soluble sugars, Si + Se > Si > Se application decreased the adverse effects of cold stress on the dry weight of the hollyhock. [ABSTRACT FROM AUTHOR]

The NAC (NAM, ATAF1/2, CUC2) family of transcription factors (TFs) is a vital transcription factor family of plants. It controls multiple parts of plant development, tissue formation, and abiotic stress response. We cloned the FvNAC29 gene from Fragaria vesca (a diploid strawberry) for this research. There is a conserved NAM structural domain in the FvNAC29 protein. The highest homology between FvNAC29 and PaNAC1 was found by phylogenetic tree analysis. Subcellular localization revealed that FvNAC29 is localized onto the nucleus. Compared to other tissues, the expression level of FvNAC29 was higher in young leaves and roots. In addition, Arabidopsis plants overexpressing FvNAC29 had higher cold and high-salinity tolerance than the wild type (WT) and unloaded line with empty vector (UL). The proline and chlorophyll contents of transgenic Arabidopsis plants, along with the activities of the antioxidant enzymes like catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) under 200 mM NaCl treatment or −8 °C treatment, were higher than those activities of the control. Meanwhile, malondialdehyde (MDA) and the reactive oxygen species (ROS) content were higher in the WT and UL lines. FvNAC29 improves transgenic plant resistance to cold and salt stress by regulating the expression levels of AtRD29a, AtCCA1, AtP5CS1, and AtSnRK2.4. It also improves the potential to tolerate cold stress by positively regulating the expression levels of AtCBF1, AtCBF4, AtCOR15a, and AtCOR47. These findings suggest that FvNAC29 may be related to the processes and the molecular mechanisms of F. vesca response to high-salinity stress and LT stress, providing a comprehensive understanding of the NAC TFs. [ABSTRACT FROM AUTHOR]

Cold stress is a serious threat to global crop production and food security, but plant cold resistance is accompanied by reductions in growth and yield. In this study, we determined that the novel gene BcGSTF10 in non-heading Chinese cabbage [NHCC; Brassica campestris (syn. Brassica rapa) ssp. chinensis ] is implicated in resistance to cold stress. Biochemical and genetic analyses demonstrated that BcGSTF10 interacts with BcICE1 to induce C-REPEAT BINDING FACTOR (CBF) genes that enhance freezing tolerance in NHCC and in Arabidopsis. However, BcCBF2 represses BcGSTF10 and the latter promotes growth in NHCC and Arabidopsis. This dual function of BcGSTF10 indicates its pivotal role in balancing cold stress and growth, and this important understanding has the potential to inform the future development of strategies to breed crops that are both climate-resilient and high-yielding. [ABSTRACT FROM AUTHOR]

One of the significant limitations in autumn cultivation of sugar beet is bolting. To investigate the quantitative and qualitative traits of root sugar beet cultivars and their resistance to bolting, a two-year (2018-2020) experiment was conducted as a randomized complete blocks design with three replications at Varsan Agricultural Research Station of Golestan Agricultural and Natural Resources Research and Education Center, Gorgan- Iran. Treatments included commercial autumn sugar beet cultivars [five imported cultivars (Montana, Jerra-kws, Rosagold, Chemineh, and Veles) and a domestic cultivar (Sharif). There was a significant difference in bolting rates of all cultivars in both years. Veles and Sharif cultivars had the highest bolting rate (41.7% and 33.3%) in both years, respectively. The bolting rate was higher in the second than in the first year. There was a significant difference between cultivars for root yield only in 2019. The highest (85.2 t ha-1) and lowest (59.8 t ha-1) root yields were obtained from Jerra-kws Chamine cultivars. There was a significant difference between cultivars for sugar purity, sugar extraction coefficient, and molasses sugar percentage in the second year. There was no significant difference between cultivars for sugar content and harmful nitrogen in both years. The cultivars showed different reactions in terms of bolting rate and other root qualitative traits (pure sugar, extraction coefficient, sodium, potassium, and harmful nitrogen levels) in the two years. [ABSTRACT FROM AUTHOR]

Calmodulin-binding transcription activator (CAMTA) is an important calmodulin-binding protein with a conserved structure in eukaryotes which is widely involved in plant stress response, growth and development, hormone signal transduction, and other biological processes. Although CAMTA genes have been identified and characterized in many plant species, a systematic and comprehensive analysis of CAMTA genes in the Solanaceae genome is performed for the first time in this study. A total of 28 CAMTA genes were identified using bioinformatics tools, and the biochemical/physicochemical properties of these proteins were investigated. CAMTA genes were categorized into three major groups according to phylogenetic analysis. Tissue-expression profiles indicated divergent spatiotemporal expression patterns of SmCAMTAs. Furthermore, transcriptome analysis of SmCAMTA genes showed that exposure to cold induced differential expression of many eggplant CAMTA genes. Yeast two-hybrid and bimolecular fluorescent complementary assays suggested an interaction between SmCAMTA2 and SmERF1, promoting the transcription of the cold key factor SmCBF2, which may be an important mechanism for plant cold resistance. In summary, our results provide essential information for further functional research on Solanaceae family genes, and possibly other plant families, in the determination of the development of plants. [ABSTRACT FROM AUTHOR]

Increasing climatic instability, along with increasing technogenic pressure on the natural environment, necessitate the search for new approaches to increasing the resistance of wheat to abiotic factors, primarily to low temperature. A promising direction is the use of metal nanoparticles, which have the ability to positively influence plant metabolism in low concentrations. Due to their small size (less than 100 nm) and special physicochemical, optical, and electrical properties, nanoparticles penetrate cellular barriers, spread throughout the plant organism, affecting almost all processes in it. With wheat as an example (Triticum aestivum L., variety Zlata), it was shown for the first time that gold nanoparticles (GNPs) can act as adaptogens, increasing the cold resistance of plants. The study used priming—soaking of seeds in GNP solutions with concentrations 5–50 μg/mL for 24 h. The plants grown from seeds treated with GNPs differed from the control (untreated) ones in a number of physiological, biochemical, and molecular genetic parameters. Their growth processes and activity of the photosynthetic apparatus were significantly enhanced, and the expression of genes encoding large (rbcL) and small (rbcS) Rubisco subunits, as well as COR genes, Wcor726 and Wcor15, were increased. Moreover, wheat plants obtained from GNP-treated seeds differed from control ones in their increased resistance to low temperatures, and the effect was manifested both under control conditions and after low-temperature hardening. Concentration tests showed that the maximum effect was achieved when using GNPs at a concentration of 10 μg/mL. It is concluded that GNPs are able to influence plant metabolism and the expression of stress response genes, which leads to a significant increase in cold resistance. Possible mechanisms of GNP action on low temperature resistance are discussed. [ABSTRACT FROM AUTHOR]

In mountain forests, tree regeneration is limited by increasingly frequent frosts with increasing elevation. We investigated the effects of exposure to freezing temperature on early life stages of two native trees of different elevational origin in a seasonally dry mountain forest. We hypothesized that the negative effects of freezing exposure on performance of early life stages increases as freezing temperature decreases, and that frost resistance increases in plants of high elevational origin.We collected seeds of two tree species (Kageneckia lanceolata and Lithraea molleoides) from populations located at different elevations and grew seedlings and saplings in a greenhouse. Dry seeds, imbibed seeds and 1‐month‐old seedlings were exposed to seven temperature treatments ranging from 4 °C to −20 °C, while 12‐month‐old saplings were exposed to four temperature treatments from −8 °C to −20 °C. After freezing exposure in a climate chamber, we monitored seed germination and seedling and sapling survival.Germination of K. lanceolata decreased with decreasing temperature only for imbibed seeds from mid‐ and high elevations, whereas germination of L. molleoides slightly increased with decreasing temperature only for imbibed seeds from high elevations. For both species, seedling survival decreased with decreasing temperature. For K. lanceolata, the negative effects of freezing temperatures were weaker as elevational origin of seeds increased, whereas L. molleoides showed the opposite pattern. For both species, saplings only survived at the mildest applied freezing temperature (−8 °C).We conclude that effects of climatic variation associated with elevation depend on the study species and life stage. The observed patterns could be caused by maternal effects, which are absent at the sapling stage. Moreover, temperatures below −8 °C can limit recruitment since partial mortality of seedlings and saplings occurred at such values. [ABSTRACT FROM AUTHOR]

Background: The basic helix-loop-helix (bHLH) gene family is one of plants' largest transcription factor families. It plays an important role in regulating plant growth and abiotic stress response. Results: In this study, we determined that the PavbHLH28 gene participated in cold resistance. The PavbHLH28 gene was located in the nucleus and could be induced by low temperature. Under the treatment of ABA, PEG, and GA3, the transcript level of PavbHLH28 was affected. At low temperature, overexpression of the PavbHLH28 gene enhanced the cold resistance of plants with higher proline content, lower electrolyte leakage (EL) and malondialdehyde (MDA) content. Compared with the WT plants, the transgenic plants accumulated fewer reactive oxygen species (ROS), and the activity and expression levels of antioxidant enzymes were significantly increased. The expression of proline synthesis enzyme genes was up-regulated, and the transcripts levels of degradation genes were significantly down-regulated. The transcripts abundance of the cold stressed-related genes in the C-repeat binding factor (CBF) pathway was not significantly different between WT plants and transgenic plants after cold stress. Moreover, the PavbHLH28 could directly bind to the POD2 gene promoter and promote its gene expression. Conclusions: Overall, PavbHLH28 enhanced the cold resistance of transgenic plants through a CBF-independent pathway, which may be partly related to ROS scavenging. [ABSTRACT FROM AUTHOR]

Cold stress poses significant limitations on the growth, latex yield, and ecological distribution of rubber trees (Hevea brasiliensis). The GSK3-like kinase plays a significant role in helping plants adapt to different biotic and abiotic stresses. However, the functions of GSK3-like kinase BR-INSENSITIVE 2 (BIN2) in Hevea brasiliensis remain elusive. Here, we identified HbBIN2s of Hevea brasiliensis and deciphered their roles in cold stress resistance. The transcript levels of HbBIN2s are upregulated by cold stress. In addition, HbBIN2s are present in both the nucleus and cytoplasm and have the ability to interact with the INDUCER OF CBF EXPRESSION1(HbICE1) transcription factor, a central component in cold signaling. HbBIN2 overexpression in Arabidopsis displays decreased tolerance to chilling stress with a lower survival rate and proline content but a higher level of electrolyte leakage (EL) and malondialdehyde (MDA) than wild type under cold stress. Meanwhile, HbBIN2 transgenic Arabidopsis treated with cold stress exhibits a significant increase in the accumulation of reactive oxygen species (ROS) and a decrease in the activity of antioxidant enzymes. Further investigation reveals that HbBIN2 inhibits the transcriptional activity of HbICE1, thereby attenuating the expression of C-REPEAT BINDING FACTOR (HbCBF1). Consistent with this, overexpression of HbBIN2 represses the expression of CBF pathway cold-regulated genes under cold stress. In conclusion, our findings indicate that HbBIN2 functions as a suppressor of cold stress resistance by modulating HbICE1 transcriptional activity and ROS homeostasis. [ABSTRACT FROM AUTHOR]

Teak is a rare tropical tree with high economic value, and it is one of the world's main afforestation trees. Low temperature is the main problem for introducing and planting this species in subtropical or temperate zones. Low-temperature acclimation can enhance the resistance of teak to low-temperature stress, but the mechanism for this is still unclear. We studied the gene expression of two-year-old teak seedlings under a rapid temperature drop from 20 °C to 4 °C using RNA-seq and WGCNA analyses. The leaves in the upper part of the plants developed chlorosis 3 h after the quick transition, and the grades of chlorosis were increased after 9 h, with the addition of water stains and necrotic spots. Meanwhile, the SOD and proline contents in teak leaves increased with the prolonged cold stress time. We also identified 36,901 differentially expressed genes, among which 1055 were novel. Notably, CBF2 and CBF4 were significantly induced by low temperatures, while CBF1 and CBF3 were not. Furthermore, WGCNA successfully identified a total of fourteen modules, which consist of three modules associated with cold stress response genes, two modules linked to CBF2 and CBF4, and one module correlated with the CBF-independent pathway gene HY5. The transformation experiments showed that TgCBF2 and TgCBF4 improved cold resistance in Arabidopsis plants. [ABSTRACT FROM AUTHOR]

1. Introduction: Potato (Solanum tuberosum L.) is one of the most important food products in the world, which is rich in carbohydrates, proteins, vitamins and other nutrients. Choosing the suitable planting date and cultivars is one of the most important and effective ways to reduce the negative effects of environmental stresses on potato characteristics. Cold stress is one of the limiting factors for production of agricultural crops. One of the adverse effects of this stress is increasing the biosynthesis rate of reactive oxygen species that causes oxidative stress. Plants have enzymatic and non-enzymatic mechanisms to overcome oxidative stress. The enzymatic antioxidant defense system includes different enzymes such as superoxide dismutase, catalase, polyphenol oxidase, guaiacol peroxidases and ascorbate peroxidase, and the non-enzymatic antioxidants include the soluble sugars, proline, carotenoids and other compounds such as flavonoids, and polyphenols. Nowadays, application of antifreeze compounds in agriculture is widely used technique to overcome chilling injuries. These substances are quickly absorbed by plants and increase the metabolic activity rate of plants. As a result, the amount of antifreeze proteins, amino acids, carbohydrates, lipids, vitamins and minerals increases in the plant organs leading to more resistance rate of plant cells against freezing. Potassium is one of the elements that reduces the effects of environmental stresses such as drought, salinity, high temperatures, cold, etc. through the accumulation of soluble carbohydrates and osmotic regulation. Also, potassium plays a role in regulating the activity of enzymes related to the detoxification of reactive oxygen species. The aim of the current study was to investigate the influence of cultivar, planting date and foliar application of antifreeze compounds on some of most important morpho-physiological characteristics of potato crop. 2. Materials and Methods: The current study was conducted as a split-factorial experiment based on randomized complete blocks design with three replications at Ardabil Agricultural and Natural Resources Research Station during two cultivation seasons (2018-2019 and 2019-2020). The investigated factors included planting date in two levels (August 1st and 11th), foliar application of antifreeze compound at two levels (foliar application with a mixture of Frezzebon amino acid + potassium, and water as a control) and potato cultivars at 10 levels (901375, 901475, 902375, 8708-7, 8709-106, 7009-3, 905675, 8707-26, Agria and Savalan). Foliar applications were performed at the end of the growth season as same time as the increased likelihood of cold weather (considering the weather forecasts and the measured temperatures in the field and their correlation, one week before the possibility of temperatures below 7 °C). Furthermore, before the spraying treatments, samples were taken from the experimental treatments and frozen using liquid nitrogen and stored in a freezer. After 24 h of freezing, the samples were again collected from the experimental treatments and rapidly frozen using liquid nitrogen before being transferred to the laboratory for measurement of the desired characteristics. After collecting the samples, laboratory experiments were conducted at the Faculty of Agriculture of Ardabil University of Medical Sciences and the Agricultural and Natural Resources Research Station in Ardabil. 3. Results and Discussion: Based on the obtained results, it was found that the foliar application of the amino acid Freezbon combined with potassium increased the yield, number of tuber per plant, leaf relative water content, proline and the activity of antioxidant enzymes. Also, the planting date of August 1st has the highest yield, number of tuber per plant, leaf relative water content, potassium and proline content, and the activity of catalase, superoxide dismutase and polyphenol oxidase enzymes. In terms of yield, 901475 cultivar had the highest yield (43.02 ton ha-1) and Agria cultivar had the lowest yield (26.35 ton ha-1). Among the cultivars studied, 8708-26 cultivar had the highest leaf relative water content, potassium and sodium content. The maximum content of proline and antioxidant enzymes activity were related to 7009-3 and 8707-26 cultivars. Based on these results, it seems that the planting date of August 1st and the foliar application of Freezbon with potassium can enhance the cold tolerance threshold, growth, and performance of potato cultivars in regions with cold weather by regulating physiological and biochemical responses. The results of the current study in line with the observations of the other conducted researches on different horticultural crops demonstrated that choosing appropriate planting date and application of antifreeze compounds positively influence the accumulation rate of osmoprotectants, cells antioxidant capacity and plant water and nutrient status resulting in a significant increase in cold resistance rate of plant cells. 4. Conclusion: Foliar application of antifreeze compounds Frezzebon amino acid + potassium, and planting date on August 1st can positively influence potato cultivars yield and physiological characteristics under cold conditions, therefore this foliar treatment and planting date are recommendable to overcome negative effects of cold stress on potato characteristics in cultivation reigns with cold weather. [ABSTRACT FROM AUTHOR]

Low temperatures restrict the growth of the grapevine industry. The DREB transcription factors are involved in the abiotic stress response. Here, we isolated the VvDREB2A gene from Vitis vinifera cultivar 'Zuoyouhong' tissue culture seedlings. The full-length VvDREB2A cDNA was 1068 bp, encoding 355 amino acids, which contained an AP2 conserved domain belonging to the AP2 family. Using transient expression in leaves of tobacco, VvDREB2A was localized to the nucleus, and it potentiated transcriptional activity in yeasts. Expression analysis revealed that VvDREB2A was expressed in various grapevine tissues, with the highest expression in leaves. VvDREB2A was induced by cold and the stress-signaling molecules H2S, nitric oxide, and abscisic acid. Furthermore, VvDREB2A-overexpressing Arabidopsis was generated to analyze its function. Under cold stress, the Arabidopsis overexpressing lines exhibited better growth and higher survival rates than the wild type. The content of oxygen free radicals, hydrogen peroxide, and malondialdehyde decreased, and antioxidant enzyme activities were enhanced. The content of raffinose family oligosaccharides (RFO) also increased in the VvDREB2A-overexpressing lines. Moreover, the expression of cold stress-related genes (COR15A, COR27, COR6.6, and RD29A) was also enhanced. Taken together, as a transcription factor, VvDREB2A improves plants resistance to cold stress by scavenging reactive oxygen species, increasing the RFO amount, and inducing cold stress-related gene expression levels. [ABSTRACT FROM AUTHOR]

Low temperatures limit the geographic distribution and yield of plants. Hormones play an important role in coordinating the growth and development of plants and their tolerance to low temperatures. However, the mechanisms by which hormones affect plant resistance to extreme cold stress in the natural environment are still unclear.In this study, two winter wheat varieties with different cold resistances, Dn1 and J22, were used to conduct targeted plant hormone metabolome analysis on the tillering nodes of winter wheat at 5 °C, −10 °C and −25 °C using an LC–ESI–MS/MS system. We screened 39 hormones from 88 plant hormone metabolites and constructed a partial regulatory network of auxin, jasmonic acid and cytokinin.GO analysis and enrichment of KEGG pathways in different metabolites showed that the 'plant hormone signal transduction' pathway was the most common. Our study showed that extreme low temperature increased the most levels of auxin, cytokinin and salicylic acid, and decreased levels of jasmonic acid and abscisic acid, and that levels of auxin, jasmonic acid and cytokinin in Dn1 were higher than those in J22. These changes in hormone levels were associated with changes in gene expression in synthesis, catabolism, transport and signal transduction pathways. These results differ from the previous hormone regulation mechanisms, which were mostly obtained at 4 °C.Our results provide a basis for further understanding the molecular mechanisms by which plant endogenous hormones regulate plant freezing stress tolerance. [ABSTRACT FROM AUTHOR]

To study the difference of cold resistance of four plants of Rosa(R. lasiosepala, R. odorata. var. gigantea, R. weisiensis, R. lichiangensis), and screen out the varieties with strong cold resistance. In this study, a low temperature incubator was used to conduct different gradients of low temperature stress(0, -5, -10, -15 ℃), the soluble sugar content, soluble protein content, malondialdehyde(MDA) content, proline(Pro) content, SOD activity, POD activity, and expression difference of coldresistance-related regulatory gene HSP90 were measured. The results showed that under low temperature stress, the soluble protein content, soluble sugar content, free proline content, malondialdehyde content, SOD activity, and POD activity in the leaves of four plants of Rosa showed a gradually increasing trend with aggravation of low temperature stress. The analysis of the differential expression of HSP90 gene of four plants of Rosa showed that the relative expression of HSP90 gene showed a trend of gradual increase with aggravation of low temperature stress. The expression of HSP90 gene was the highest in R. lasiosepala under 0, - 5, - 10, -15 ℃ low temperature stress, indicating that there were differences in cold resistance of four plants of Rosa, among which R. lasiosepala had better cold resistance. [ABSTRACT FROM AUTHOR]

Low temperature is an important factor limiting plant growth. Most cultivars of Vitis vinifera L. are sensitive to low temperatures and are at risk of freezing injury or even plant death during winter. In this study, we analyzed the transcriptome of branches of dormant cv. Cabernet Sauvignon exposed to several low-temperature conditions to identify differentially expressed genes and determine their function based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG)enrichment analyses. Our results indicated that exposure to subzero low temperatures resulted in damage to plant cell membranes and extravasation of intracellular electrolytes, and that this damage increased with decreasing temperature or increasing duration. The number of differential genes increased as the duration of stress increased, but most of the common differentially expressed genes reached their highest expression at 6 h of stress, indicating that 6 h may be a turning point for vines to tolerate extreme low temperatures. Several pathways play key roles in the response of Cabernet Sauvignon to low-temperature injury, namely: (1) the role of calcium/calmodulin-mediated signaling; (2) carbohydrate metabolism, including the hydrolysis of cell wall pectin and cellulose, decomposition of sucrose, synthesis of raffinose, and inhibition of glycolytic processes; (3) the synthesis of unsaturated fatty acids and metabolism of linolenic acid; and (4) the synthesis of secondary metabolites, especially flavonoids. In addition, pathogenesis-related protein may also play a role in plant cold resistance, but the mechanism is not yet clear. This study reveals possible pathways for the freezing response and leads to new insights into the molecular basis of the tolerance to low temperature in grapevine. [ABSTRACT FROM AUTHOR]

Cold stress is one of the major abiotic stresses limiting tea production. The planting of cold-resistant tea cultivars is one of the most effective measures to prevent chilling injury. However, the differences in cold resistance between tea cultivars remain unclear. In the present study, we perform a transcriptomic and metabolomic profiling of Camellia sinensis var. "Shuchazao" (cold-tolerant, SCZ) and C. sinensis var. assamica "Yinghong 9" (cold-sensitive, YH9) during cold acclimation and analyze the correlation between gene expression and metabolite biosynthesis. Our results show that there were 51 differentially accumulated metabolites only up-regulated in SCZ in cold–acclimation (CA) and de–acclimation (DA) stages, of which amino acids accounted for 18%. The accumulation of L-arginine and lysine in SCZ in the CA stage was higher than that in YH9. A comparative transcriptomic analysis showed an enrichment of the amino acid biosynthesis pathway in SCZ in the CA stage, especially "arginine biosynthesis" pathways. In combining transcriptomic and metabolomic analyses, it was found that genes and metabolites associated with amino acid biosynthesis were significantly enriched in the CA stage of SCZ compared to CA stage of YH9. Under cold stress, arginine may improve the cold resistance of tea plants by activating the polyamine synthesis pathway and CBF (C-repeat-binding factor)–COR (cold-regulated genes) regulation pathway. Our results show that amino acid biosynthesis may play a positive regulatory role in the cold resistance of tea plants and assist in understanding the cold resistance mechanism differences among tea varieties. [ABSTRACT FROM AUTHOR]

Malus baccata (L.) Borkh is an apple rootstock with good drought and cold resistance. The ICE gene is a key factor in the molecular mechanisms of plant drought and cold resistance. In the present research, the function of drought- and cold-induced MbICE1 of Malus baccata was investigated in Arabidopsis. According to GFP fluorescence images, MbICE1 was determined to be a nuclear protein. The MbICE1 was transferred to Arabidopsis, showing enhanced tolerance to drought and cold stresses. Under drought and cold treatments, the transgenic Arabidopsis had higher chlorophyll content and free proline content than WT plants, but the Malondialdehyde (MDA) content and electrolyte leakage (EL) were lower than those of WT plants. In addition, drought and cold led to a large accumulation of ROS (H2O2 and O2−) content in Arabidopsis, while overexpression of MbICE1 enhanced the antioxidant enzyme activity in Arabidopsis and improved the plant's resistance to stresses. Moreover, the accumulation of MbICE1 promoted the expression of AtCBF1, AtCBF2, AtCBF3, AtCOR15a, AtCOR47 and AtKIN1 genes in Arabidopsis. These data indicate that MbICE1 is a key regulator of drought and cold and can be used as a backup gene for breeding Malus rootstocks. [ABSTRACT FROM AUTHOR]

ICE1, a regulator of the cold-inducible transcriptome and freezing tolerance, is currently widely believed to be involved in plant resistance to cold stress. In this study, CfICE1 from Cryptomeria fortunei was transformed into poplar. Physiological indicators of transgenic, empty vector and wild-type poplar after abiotic stress (cold, drought and salt) were determined. Transgenic lines had a higher chlorophyll content, antioxidant enzyme activity and soluble protein content, as well as a lower malondialdehyde and hydrogen peroxide content. The ultrastructure of the plant was observed by transmission electron microscopy, and after stress, the cell structure of the transgenic line was more complete than that of the wild type. CfICE1 was upregulated in transgenic poplar trees after abiotic stress (cold, drought and salt). The CfICE1 transgenic plants improved plant resistance by regulating the CBF gene of poplar under cold and salt stress. In terms of plant responses to abiotic stress, this study showed that overexpression of CfICE1 improved the cold, drought and salt tolerance of poplars. [ABSTRACT FROM AUTHOR]

Data are presented on the features of winter wheat adaptation (Triticum aestivum L., cultivar Moskovskaya 39) to frost as a result of low hardening temperatures of varying intensity. A comparative analysis of the dynamics of indicators characterizing frost resistance, growth, transpiration rate, the intensity of oxidative processes, the state of the photosynthetic apparatus, the structure of leaf cells, and the level of WCOR15 gene transcripts (coding for a cold response protein) was carried out during hardening of wheat plants at temperatures of 12, 8, and 4°C. It is shown that, during cold adaptation, the "reprogramming" of the plant organism occurs, the degree and depth of which are determined by the intensity of low-temperature exposure: the closer the hardening temperature is to damaging values, the faster and more significant adaptive changes it causes, and the greater frost resistance plants are able to develop in the process of hardening. [ABSTRACT FROM AUTHOR]

Breeding for flower cold resistance is a priority for flower breeding research in northern China. The identification of cold resistance genes will not only provide genetic resources for cold resistance breeding, but also form a basis for the study of plant cold resistance mechanisms.Based on the flower transcriptome of Iris laevigata, 20 R2R3‐MYBs were identified and comprehensive analysis, including conservative domain, phylogenetic analyses and functional distribution, were performed for R2R3‐MYBs. Expression patterns of the abiotic stress genes under cold stress were detected, the upregulated gene was genetically transformed into tobacco, and the related physiological indicators of the transgenic tobacco were measured.A novel cold resistance gene, IlMYB306, was obtained. qRT‐PCR indicated that IlMYB306 was dramatically induced by cold stress and was significantly upregulated in roots. The free proline content, MDA, SOD and POD activity of the transgenic tobacco improved after cold stress, and the chlorophyll content decreased slowly. In addition, overexpression of IlMYB306 improved cold resistance of the seeds. SEM results showed leaves of transgenic tobacco had obvious folds, more grooves and bulges on the lower leaf surface.Overall, we report a novel cold resistance R2R3‐MYB gene, IlMYB306, in the flower of I. laevigata, which could improve tobacco cold stress tolerance by thickening the waxy layer, increasing antioxidant activity and the content of proline. [ABSTRACT FROM AUTHOR]

Cold stress limits plant growth, development and yields, and the C-repeat binding factors (CBFs) function in the cold resistance in plants. However, how pomegranate CBF transcription factors respond to cold signal remains unclear. Considering the significantly up-regulated expression of PgCBF3 and PgCBF7 in cold-tolerant Punica granatum 'Yudazi' in comparison with cold-sensitive 'Tunisia' under 4 °C, the present study focused on the two CBF genes. PgCBF3 was localized in the nucleus, while PgCBF7 was localized in the cell membrane, cytoplasm, and nucleus, both owning transcriptional activation activity in yeast. Yeast one-hybrid and dual-luciferase reporter assay further confirmed that PgICE1 could specifically bind to and significantly enhance the activation activity of the promoters of PgCBF3 and PgCBF7. Compared with the wild-type plants, the PgCBF3 and PgCBF7 transgenic Arabidopsis thaliana lines had the higher survival rate after cold treatment; exhibited increased the contents of soluble sugar and proline, while lower electrolyte leakage, malondialdehyde content, and reactive oxygen species production, accompanying with elevated enzyme activity of catalase, peroxidase, and superoxide dismutase; and upregulated the expression of AtCOR15A, AtCOR47, AtRD29A, and AtKIN1. Collectively, PgCBFs were positively regulated by the upstream PgICE1 and mediated the downstream COR genes expression, thereby enhancing freezing tolerance. [ABSTRACT FROM AUTHOR]

The presence of sugar in plant tissue can lead to an increase in the osmotic pressure within cells, a decrease in the freezing point of plants, and protection against ice crystal damage to the tissue. Trehalose is closely related to sucrose, which comprises the largest proportion of sugar and has become a hot topic of research in recent years. Our previous studies have confirmed that a key trehalose synthesis gene, TaTPS11 , from the cold-resistant winter wheat DM1, could enhance the cold resistance of plants by increasing sugar content. However, the underlying mechanism behind this phenomenon remains unclear. In this study, we cloned TaTPS11-6D , edited TaTPS11-6D using CRISPR/Cas9 technology and transformed 'Fielder' to obtain T 2 generation plants. We screened out OE3-3 and OE8-7 lines with significantly higher cold resistance than that of 'Fielder' and Cri 4–3 edited lines with significantly lower cold resistance than that of 'Fielder'. Low temperature storage limiting factors were measured for OE3-3, OE8-7 and Cri 4–3 treated at different temperatures.The results showed that TaTPS11-6D significantly increased the content of sugar in plants and the transfer of sugar from source to storage organs under cold conditions. The TaTPS11-6D significantly increased the levels of salicylic, jasmonic, and abscisic acids while also significantly decreasing the level of gibberellic acid. Our research improves the model of low temperature storage capacity limiting factor. • TaTPS11-6D significantly increased the content of sugar in plants and the transfer of sugar from source to storage organs under cold conditions. • Trehalose content is limited by sucrose degradation, not TPS activity. • TaTPS11-6D regulates the synthesis, degradation, and transport of sucrose to modulate plant cold resistance. [ABSTRACT FROM AUTHOR]

Background: Low temperature is a crucial stress factor of wheat (Triticum aestivum L.) and adversely impacts on plant growth and grain yield. Multi-million tons of grain production are lost annually because crops lack the resistance to survive in winter. Particularlly, winter wheat yields was severely damaged under extreme cold conditions. However, studies about the transcriptional and metabolic mechanisms underlying cold stresses in wheat are limited so far. Results: In this study, 14,466 differentially expressed genes (DEGs) were obtained between wild-type and cold-sensitive mutants, of which 5278 DEGs were acquired after cold treatment. 88 differential accumulated metabolites (DAMs) were detected, including P-coumaroyl putrescine of alkaloids, D-proline betaine of mino acids and derivativ, Chlorogenic acid of the Phenolic acids. The comprehensive analysis of metabolomics and transcriptome showed that the cold resistance of wheat was closely related to 13 metabolites and 14 key enzymes in the flavonol biosynthesis pathway. The 7 enhanced energy metabolites and 8 up-regulation key enzymes were also compactly involved in the sucrose and amino acid biosynthesis pathway. Moreover, quantitative real-time PCR (qRT-PCR) revealed that twelve key genes were differentially expressed under cold, indicating that candidate genes POD, Tacr7, UGTs, and GSTU6 which were related to cold resistance of wheat. Conclusions: In this study, we obtained the differentially expressed genes and differential accumulated metabolites in wheat under cold stress. Using the DEGs and DAMs, we plotted regulatory pathway maps of the flavonol biosynthesis pathway, sucrose and amino acid biosynthesis pathway related to cold resistance of wheat. It was found that candidate genes POD, Tacr7, UGTs and GSTU6 are related to cold resistance of wheat. This study provided valuable molecular information and new genetic engineering clues for the further study on plant resistance to cold stress. [ABSTRACT FROM AUTHOR]

Background: Low temperature is a crucial stress factor of wheat (Triticum aestivum L.) and adversely impacts on plant growth and grain yield. Multi-million tons of grain production are lost annually because crops lack the resistance to survive in winter. Particularlly, winter wheat yields was severely damaged under extreme cold conditions. However, studies about the transcriptional and metabolic mechanisms underlying cold stresses in wheat are limited so far. Results: In this study, 14,466 differentially expressed genes (DEGs) were obtained between wild-type and cold-sensitive mutants, of which 5278 DEGs were acquired after cold treatment. 88 differential accumulated metabolites (DAMs) were detected, including P-coumaroyl putrescine of alkaloids, D-proline betaine of mino acids and derivativ, Chlorogenic acid of the Phenolic acids. The comprehensive analysis of metabolomics and transcriptome showed that the cold resistance of wheat was closely related to 13 metabolites and 14 key enzymes in the flavonol biosynthesis pathway. The 7 enhanced energy metabolites and 8 up-regulation key enzymes were also compactly involved in the sucrose and amino acid biosynthesis pathway. Moreover, quantitative real-time PCR (qRT-PCR) revealed that twelve key genes were differentially expressed under cold, indicating that candidate genes POD, Tacr7, UGTs, and GSTU6 which were related to cold resistance of wheat. Conclusions: In this study, we obtained the differentially expressed genes and differential accumulated metabolites in wheat under cold stress. Using the DEGs and DAMs, we plotted regulatory pathway maps of the flavonol biosynthesis pathway, sucrose and amino acid biosynthesis pathway related to cold resistance of wheat. It was found that candidate genes POD, Tacr7, UGTs and GSTU6 are related to cold resistance of wheat. This study provided valuable molecular information and new genetic engineering clues for the further study on plant resistance to cold stress. [ABSTRACT FROM AUTHOR]

SUMMARY: Cucumber (Cucumis sativus) originated in tropical areas and is very sensitive to low temperatures. Cold acclimation is a universal strategy that improves plant resistance to cold stress. In this study, we report that heat shock induces cold acclimation in cucumber seedlings, via a process involving the heat‐shock transcription factor HSFA1d. CsHSFA1d expression was improved by both heat shock and cold treatment. Moreover, CsHSFA1d transcripts accumulated more under cold treatment after a heat‐shock pre‐treatment than with either heat shock or cold treatment alone. After exposure to cold, cucumber lines overexpressing CsHSFA1d displayed stronger tolerance for cold stress than the wild type, whereas CsHSFA1d knockdown lines obtained by RNA interference were more sensitive to cold stress. Furthermore, both the overexpression of CsHSFA1d and heat‐shock pre‐treatment increased the endogenous jasmonic acid (JA) content in cucumber seedlings after cold treatment. Exogenous application of JA rescued the cold‐sensitive phenotype of CsHSFA1d knockdown lines, underscoring that JA biosynthesis is key for CsHSFA1d‐mediated cold tolerance. Higher JA content is likely to lead to the degradation of CsJAZ5, a repressor protein of the JA pathway. We also established that CsJAZ5 interacts with CsICE1. JA‐induced degradation of CsJAZ5 would be expected to release CsICE1, which would then activate the ICE–CBF–COR pathway. After cold treatment, the relative expression levels of ICE–CBF–COR signaling pathway genes, such as CsICE1, CsCBF1, CsCBF2 and CsCOR1, in CsHSFA1d overexpression lines were significantly higher than in the wild type and knockdown lines. Taken together, our results help to reveal the mechanism underlying heat shock‐induced cold acclimation in cucumber. Significance Statement: Cold acclimation is a universal strategy that improves plant resistance to cold stress. In this study, we discovered that a heat‐shock pre‐treatment improves the tolerance of cucumber seedlings for low‐temperature stress, and that CsHSFA1d and JA play important roles in this cold acclimation process. Our results will help to reveal the mechanism underlying heat shock‐induced cold acclimation in cucumber. [ABSTRACT FROM AUTHOR]

Background: Cold stress is one of the main abiotic stresses limiting cucumber (Cucumis sativus L.) growth and production. C-repeat binding factor/Dehydration responsive element-binding 1 protein (CBF/DREB1), containing conserved APETALA2 (AP2) DNA binding domains and two characteristic sequences, are key signaling genes that can be rapidly induced and play vital roles in plant response to low temperature. However, the CBF family has not been systematically elucidated in cucumber, and the expression pattern of this family genes under cold stress remains unclear. Results: In this study, three CsCBF family genes were identified in cucumber genome and their protein conserved domain, protein physicochemical properties, gene structure and phylogenetic analysis were further comprehensively analyzed. Subcellular localization showed that all three CsCBFs were localized in the nucleus. Cis-element analysis of the promoters indicated that CsCBFs might be involved in plant hormone response and abiotic stress response. Expression analysis showed that the three CsCBFs could be significantly induced by cold stress, salt and ABA. The overexpression of CsCBFs in cucumber seedlings enhanced the tolerance to cold stress, and importantly, the transcript levels of CsCOR genes were significantly upregulated in 35S:CsCBFs transgenic plants after cold stress treatment. Biochemical analyses ascertained that CsCBFs directly activated CsCOR genes expression by binding to its promoter, thereby enhancing plant resistance to cold stress. Conclusion: This study provided a foundation for further research on the function of CsCBF genes in cold stress resistance and elucidating its mechanism. [ABSTRACT FROM AUTHOR]

Background: The Sugars Will Eventually be Exported Transporters (SWEETs) are a newly discovered family of sugar transporters whose members exist in a variety of organisms and are highly conserved. SWEETs have been reported to be involved in the growth and development of many plants, but little is known about SWEETs in daylily (Hemerocallis fulva), an important perennial ornamental flower. Results: In this study, 19 daylily SWEETs were identified and named based on their homologous genes in Arabidopsis and rice. Phylogenetic analysis classified these HfSWEETs into four clades (Clades I to IV). The conserved motifs and gene structures showed that the HfSWEETs were very conservative during evolution. Chromosomal localization and synteny analysis found that HfSWEETs were unevenly distributed on 11 chromosomes, and there were five pairs of segmentally duplicated events and one pair of tandem duplication events. The expression patterns of the 19 HfSWEETs showed that the expression patterns of most HfSWEETs in different tissues were related to corresponding clades, and most HfSWEETs were up-regulated under low temperatures. Furthermore, HfSWEET17 was overexpressed in tobacco, and the cold resistance of transgenic plants was much higher than that of wild-type tobacco. Conclusion: This study identified the SWEET gene family in daylily at the genome-wide level. Most of the 19 HfSWEETs were expressed differently in different tissues and under low temperatures. Overexpression further suggests that HfSWEET17 participates in daylily low-temperature response. The results of this study provide a basis for further functional analysis of the SWEET family in daylily. [ABSTRACT FROM AUTHOR]

Winter field survival (WFS) in autumn-seeded winter cereals is a complex trait associated with low temperature tolerance (LTT), prostrate growth habit (PGH), and final leaf number (FLN). WFS and the three sub-traits were analyzed by a genome-wide association study of 96 rye (Secale cereal L.) genotypes of different origins and winter-hardiness levels. A total of 10,244 single nucleotide polymorphism (SNP) markers were identified by genotyping by sequencing and 259 marker-trait-associations (MTAs; p < 0.01) were revealed by association mapping. The ten most significant SNPs (p < 1.49e−04) associated with WFS corresponded to nine strong candidate genes: Inducer of CBF Expression 1 (ICE1), Cold-regulated 413-Plasma Membrane Protein 1 (COR413-PM1), Ice Recrystallization Inhibition Protein 1 (IRIP1), Jasmonate-resistant 1 (JAR1), BIPP2C1-like protein phosphatase, Chloroplast Unusual Positioning Protein-1 (CHUP1), FRIGIDA-like 4 (FRL4-like) protein, Chalcone Synthase 2 (CHS2), and Phenylalanine Ammonia-lyase 8 (PAL8). Seven of the candidate genes were also significant for one or several of the sub-traits supporting the hypothesis that WFS, LTT, FLN, and PGH are genetically interlinked. The winter-hardy rye genotypes generally carried additional allele variants for the strong candidate genes, which suggested allele diversity was a major contributor to cold acclimation efficiency and consistent high WFS under varying field conditions. [ABSTRACT FROM AUTHOR]

As the direct recipients of plant abscisic acid (ABA), pyrabactin resistance/pyrabactin resistance-like/regulatory component of ABA receptor proteins (PYR/PYL/RCAR; hereinafter called PYLs) play pivotal roles in plant coercive responses. However, the PYL genes in Acer palmatum have yet to be investigated. In this study, using a genome search method, we identified 14 A. palmatum PYL genes (ApPYLs) and clustered them into three clades based on the phylogenetic, gene structure, and conserved motif analyses. The ApPYLs were dispersed on eight chromosomes of A. palmatum ; cis -acting element analysis indicated that the ApPYLs were involved in biological processes, including resistance, hormone regulation, and growth. Gene expression profiling of cold-treated A. palmatum plants revealed that ApPYL1 and ApPYL2 may be related to cold stress response. ApPYL1 and ApPYL2 interacted directly with ApMYB44 , and the ApPYL1 , ApPYL2 , and ApMYB44 genes were found to enhance freezing tolerance in Arabidopsis. These findings illustrate that ApPYL1 and ApPYL2 respond to the cold signalling pathway by interacting with ApMYB44 and provide a reference for improving cold resistance of plants. • Fourteen PYL genes in three subgroups were identified in the A. palmatum genome. • ApPYL1 and ApPYL2 were highly expressed after exposure to cold stress. • ApPYL1 and ApPYL2 overexpression improved frost resistance in A. thaliana. • ApPYL1/ApPYL2–ApMYB44 complex may be involved in cold signalling response. [ABSTRACT FROM AUTHOR]

Alkaline/neutral invertase (A/N-Inv) is a type of hydrolases that irreversibly hydrolyze sucrose into glucose and fructose, thus participating in the plant morphogenesis and stress responses. In tea plant, a putative A/N-Inv gene, CsINV2 , mediated the abiotic stress responses of tea plant, but the detailed molecular mechanism has not been elucidated yet. In this study, CsINV2 was verified as an alkaline invertase that can split sucrose into glucose and fructose in vitro, which showed the optimal catalytic activity at 45 °C and pH 8 conditions. Besides, the high transcription of CsINV2 contributed to improving the cold adaptation of tea plant, while silencing of CsINV2 reduced cold adaptive of tea plant. Overexpression of CsINV2 improved freezing tolerance of transgenic Arabidopsis by improving A/N-Inv activity, glucose content, hexose/sucrose ratio, and also via a feedback regulation pathway. Meanwhile, overexpression of CsINV2 promoted gemination rate and root elongation of transgenic Arabidopsis under salt stress condition. Finally, a cold-induced transcription factor CsAHL17 was confirmed to interact with the promoter of CsINV2 , silencing of CsAHL17 reduced the transcription of CsINV2 both under 25 °C and 4 °C conditions. In summary, it can draw a conclusion that CsINV2 regulates the cold resistance of tea plant by influencing the contents of different soluble sugar components under the regulation of CsAHL17. This study will further promote the understanding to the role of invertase in tea plants. • CsINV2 is alkaline invertase with the optimum catalytic activity at pH 8 and 45 °C. • CsINV2 improves cold adaptive of tea plant. • Overexpression CsINV2 enhances cold and salt tolerance of transgenic Arabidopsis. • CsAHL17 regulates the transcription of CsINV2. [ABSTRACT FROM AUTHOR]

Alternative splicing (AS) was an important post-transcriptional mechanism that involved in plant resistance to adversity stress. WRKY transcription factors function as transcriptional activators or repressors to modulate plant growth, development and stress response. However, the role of alternate splicing of WRKY in cold tolerance is poorly understood in tea plants. In this study, we found that the CsWRKY21 transcription factor, a member of the WRKY IId subfamily, was induced by low temperature. Subcellular localization and transcriptional activity assays showed that CsWRKY21 localized to the nucleus and had no transcriptional activation activity. Y1H and dual-luciferase reporter assays showed that CsWRKY21 suppressed expression of CsABA8H and CsUGT by binding with their promoters. Transient overexpression of CsABA8H and CsUGT reduced abscisic acid (ABA) content in tobacco leaves. Furthermore, we discovered that CsWRKY21 undergoes AS in the 5′UTR region. The AS transcript CsWRKY21-b was induced at low temperature, up to 6 folds compared to the control, while the full-length CsWRKY21-a transcript did not significantly change. Western blot analysis showed that the retention of introns in the 5′UTR region of CsWRKY21-b led to higher CsWRKY21 protein content. These results revealed that alternative splicing of CsWRKY21 involved in cold tolerance of tea plant by regulating the protein expression level and then regulating the content of ABA, and provide insights into molecular mechanisms of low temperature defense mediated by AS in tea plant. • CsWRKY21 participates in the cold resistance of tea plants by regulating the expression of CsABA8H and CsUDP to regulate ABA content. • The alternative splicing transcript CsWRKY21-b was induced 6 folds compared to the control at low temperature rather than its full-length transcript. • 5′ UTR region retained by introns affect level of protein translation. [ABSTRACT FROM AUTHOR]

Low temperatures can severely affect plant growth and reduce their ornamental value. A family of plant histone deacetylases allows plants to cope with both biotic and abiotic stresses. In this study, we screened and cloned the cDNA of DgSRT2 obtained from transcriptome sequencing of chrysanthemum leaves under low-temperature stress. Sequence analysis showed that DgSRT2 belongs to the sirtuin family of histone deacetylases. We obtained the stable transgenic chrysanthemum lines OE-2 and OE-12. DgSRT2 showed tissue specificity in wild-type chrysanthemum and was most highly expressed in leaves. Under low-temperature stress, the OE lines showed higher survival rates, proline content, solute content, and antioxidant enzyme activities, and lower relative electrolyte leakage, malondialdehyde, hydrogen peroxide, and superoxide ion accumulation than the wild-type lines. This work suggests that DgSRT2 can serve as an essential gene for enhancing cold resistance in plants. In addition, a series of cold-responsive genes in the OE line were compared with WT. The results showed that DgSRT2 exerted a positive regulatory effect by up-regulating the transcript levels of cold-responsive genes. The above genes help to increase antioxidant activity, maintain membrane stability and improve osmoregulation, thereby enhancing survival under cold stress. It can be concluded from the above work that DgSRT2 enhances chrysanthemum tolerance to low temperatures by scavenging the ROS system. • The experimental methods used in this study were mainly real-time fluorescence quantification (qRT-PCR), agrobacterium mediated method, and physiological index measurements. • Histone deacetylase SRT2 is most likely localized to the mitochondrial membrane of chrysanthemum and is tissue specific in chrysanthemum. • DgSRT2 has the ability to regulate the reactive oxygen species scavenging system under low-temperature stress. • DgSRT2 was up-regulated in chrysanthemum under low temperature stress and was located upstream of some of the cold resistance-related genes. [ABSTRACT FROM AUTHOR]

Caleosin is a lipid droplet‐binding protein involved in maintenance of the lipid droplet structure and in signal transduction. However, the role of caleosin proteins in stress resistance is limited. Here, we report data for a rice caleosin protein gene, OsClo5, involved in cold stress tolerance via influence and regulation of the JA signalling pathway.Overexpression lines and RNAi lines of OsClo5 were subjected to cold stress and recovery to measure electrolyte leakage and survival rate. Changes were also detected in the genome‐wide transcriptome of OsClo5 overexpressed plants.OsClo5 is located mainly in lipid droplets and expressed in all tissues tested. Its expression was upregulated by various stress conditions when subjected to cold treatment. Overexpression of OsClo5 decreased cold tolerance, and RNAi lines of OsClo5 had higher survival than WT seedlings. OsClo5 inhibited one jasmonate biosynthetic gene and several jasmonate ZIM domain (JAZ) genes, which were upregulated in response to cold stress.OsClo5 is a constitutively expressed caleosin protein that regulates plant cold resistance through inhibition of jasmonate signalling and JA synthesis. [ABSTRACT FROM AUTHOR]

The objective of the present study is to examine the changes in some indicators characterizing the winter hardiness of bee colonies settled in hives made of different material (polystyrene, wood, ceramics) and with different type of bottom (lattice or solid). Some parameters which characterize the wintering of bee colonies (amount of dead bees and quantity of food consumption in winter) have been investigated. The bee colonies were housed in 10-frame Dadant Blatt hives with a lattice and solid bottom situated at the Training Apiary of the Faculty of Agriculture, Trakia University, Stara Zagora, Bulgaria. Two inspections of the bee colonies were carried out (during wintering in November 2020 and at the beginning of the active season in March 2021). Amount of bees in the bee hive (strength) and amount of capped honey in the honeycombs were reported. In bee colonies wintering in hives with a lattice bottom, the consumption of food per 1 kg of bees was 1.639 kg (50%) higher than in hives with a solid bottom. Winter mortality of bees in hives with a lattice bottom was higher compared to this indicator in the hives with a solid bottom, 16.19±10.72% and 12.59±3.57%, respectively, which can be considered excellent wintering below 15% and good wintering in the range of 15.0-19.99%. [ABSTRACT FROM AUTHOR]

How to develop a simple and economic approach to improve plant cold stress tolerance is an important scientific problem. With the hope that we explored the effect and metabolism of cold plasma (CP) seed treatment on the chilling tolerance in tomato plants. 75 W CP seed treatment showed the best mitigative effect on cold-induced injury of tomato seedlings, as evidenced by the higher maximum photochemical efficiency of PSII (F v / F m), lower ion leakage and chilling injury index. Moreover, the results showed that CP-induced chilling tolerance was related to the hydrogen peroxide (H 2 O 2) mediated by respiratory burst oxidase homologue 1 (RBOH1), which was proved by the decrease low temperature tolerance observed in RBOH1 silence or chemical scavenging of H 2 O 2 seedlings. Furthermore, RBOH1 -mediated H 2 O 2 acted as the downstream signaling of CP treatment to enhance the levels of abscisic acid (ABA) by increasing the transcript of 9-cis-epoxycarotenoid dioxygenase 1 (NCED1). Mutation of NCED1 completely abolished CP-induced cold resistance. Genetic evidence showed that H 2 O 2 and ABA were positive regulators of cold stress tolerance. Thus, CP-induced H 2 O 2 and ABA cascade signal up-regulated the regulatory genes (ICE1 and CBF1) of cold acclimation, which increased the osmotic adjustment substances (proline and soluble sugar) accumulation and antioxidant enzymes (SOD, APX and CAT) activities. Our results indicate that H 2 O 2 and ABA signals are involved in conferring cold stress tolerance induced by CP seed treatment in tomato plants. [Display omitted] • CP seed treatment can improve cold resistance in tomato plants. • ROS and ABA are firstly evidenced to take part in CP-induced cold resistance. • The period of validity of CP-induced cold resistance is evaluated firstly. [ABSTRACT FROM AUTHOR]

Background: Banana is a tropical fruit with a high economic impact worldwide. Cold stress greatly affects the development and production of banana. Results: In the present study, we investigated the functions of MaMAPK3 and MaICE1 involved in cold tolerance of banana. The effect of RNAi of MaMAPK3 on Dajiao (Musa spp. 'Dajiao'; ABB Group) cold tolerance was evaluated. The leaves of the MaMAPK3 RNAi transgenic plants showed wilting and severe necrotic symptoms, while the wide-type (WT) plants remained normal after cold exposure. RNAi of MaMAPK3 significantly changed the expressions of the cold-responsive genes, and the oxidoreductase activity was significantly changed in WT plants, while no changes in transgenic plants were observed. MaICE1 interacted with MaMAPK3, and the expression level of MaICE1 was significantly decreased in MaMAPK3 RNAi transgenic plants. Over-expression of MaICE1 in Cavendish banana (Musa spp. AAA group) indicated that the cold resistance of transgenic plants was superior to that of the WT plants. The POD P7 gene was significantly up-regulated in MaICE1-overexpressing transgenic plants compared with WT plants, and the POD P7 was proved to interact with MaICE1. Conclusions: Taken together, our work provided new and solid evidence that MaMAPK3-MaICE1-MaPOD P7 pathway positively improved the cold tolerance in monocotyledon banana, shedding light on molecular breeding for the cold-tolerant banana or other agricultural species. [ABSTRACT FROM AUTHOR]

The forage species Caucasian clover (Trifolium ambiguum M. Bieb.), a groundcover plant, is resistant to both cold and drought. However, reference genes for qRT-PCR-based analysis of Caucasian clover are lacking. In this study, 12 reference genes were selected on the basis of transcriptomic data. These genes were used to determine the most stably expressed genes in various organs of Caucasian clover under cold, salt and drought stress for qRT-PCR-based analysis. Reference gene stability was analyzed by geNorm, NormFinder, BestKeeper, the ∆Ct method and RefFinder. Under salt stress, RCD1 and PPIL3 were the most stable reference genes in the leaves, and NLI1 and RCD1 were the most stable references genes in the roots. Under low-temperature stress, APA and EFTu-GTP were the most stable reference genes in the leaves, and the RCD1 and NLI2 genes were highly stable in the roots. Under 10% PEG-6000 stress, NLI1 and NLI2 were highly stable in the leaves, and RCD1 and PPIL3 were the most stable in the roots. Overall, RCD1 and NLI2 were the most stable reference genes in organs under normal conditions and across all samples. The most and least stable reference genes were validated by assessing their appropriateness for normalization via WRKY genes. [ABSTRACT FROM AUTHOR]

The MEDIATOR (MED) complex is a molecular bridge that regulates transcription by connecting transcription factors (TFs) and specific gene promoters. The MED subunit 25 (MED25) can interact with specific TFs in the phytohormone signaling pathways to regulate the transcription of downstream genes and affect various physiological processes in plants. Although MED25 plays an important role in adaptation to abiotic stresses, it is still unclear whether MED25 is involved in freezing tolerance in wheat. In this study, we found that the expression of TaMED25 was significantly increased under extremely low temperatures (–25 °C) in Dongnongdongmai1 (Dn1) plants, a variety of winter wheat with excellent cold-stress resistance,and hypothesized that TaMED25 may be a novel regulator of freezing tolerance in this wheat variety. To further characterize the function of TaMED25 in freezing tolerance, we cloned TaMED25 from Dn1 plants and overexpressed it in Arabidopsis thaliana. The results showed that the overexpression of TaMED25 improved freezing tolerance in Arabidopsis plants, with decreased relative conductivity, enhanced ability to effectively scavenge reactive oxygen species (ROS), and increased expression of cold-responsive genes. Furthermore, we proposed that TaMED25 mediates jasmonate-induced cold resistance in plants, possibly by interacting with TaJAZ7 and TaMYC2 of the jasmonate signaling pathway and TaICE41 of the ICE–CBF–COR pathway. Our findings reveal the functions of MED25 in plants and provide a scientific basis for an in-depth analysis of the transcriptional regulation mechanism of freezing tolerance in winter wheat. • TaMED25 is involved in JA signal pathway. • TaMED25 expression is responsed to low temperature stress in wheat. • Overexpression of TaMED25 gene enhances freeze resistance in Arabidopsis plants. • TaMED25 is localized in the nucleus. • TaMED25 interacts with TaJAZ7, TaMYC2 and TaICE41 proteins. [ABSTRACT FROM AUTHOR]

A total of 120 nodal segments of Chrysanthemum 'Gongju' plantlets were treated with colchicine to obtain autopolyploidy. Flow cytometry showed that 1 of the 12 surviving seedlings had DNA contents that were twice that of tetraploid plants. Microscopy revealed that the epidermal cell and stomatal area of octoploid plant leaves were larger than those of tetraploid plant leaves. Morphological characteristics showed that the plant height of octoploid plants did not differ from that of tetraploid plants, but their leaves and flowers remarkably varied. The leaves and flowers of octoploid plants were larger than those of tetraploid plants. The diameters of the inflorescence and disc flower of octoploid plants increased by 7.2% and 28.4% compared with those of tetraploid plants, respectively. Similarly, the numbers of their ligulate and tubular flowers increased by 22.6% and 34.0% compared with those of tetraploid plants, respectively. Semi-lethal temperature (LT50) of tetraploid plants was − 8.58 °C, while LT50 of octoploid plants decreased by 3.4 °C. At low temperatures, the relative expression levels of CmICE, CmDREB, CmCOR, CmPYR1, CmFAD, CmWRI, CmBAM, and CmPSP genes related to cold resistance in octoploid plants were higher than those in tetraploid plants. Conversely, the expression levels of CmAPX and CmGSH in octoploid plants were lower than those in tetraploid plants. The relative expression levels of CmOST, CmPDH, and CmOAT did not differ between octoploid and tetraploid plants. [ABSTRACT FROM AUTHOR]

Abiotic stresses alter the expression of multiple genes in plants allowing them to accommodate to hostile environmental conditions. Exposure to low temperatures in the autumn prior to winter is a crucial environmental factor determining an increase in freezing tolerance and winter hardiness in temperate plants. The objective of this study was to evaluate transcriptome changes under a short-term low temperature stress using an RNA-Seq approach in winter wheat (Triticum aestivum L.). Significant alterations were observed for nuclear transcriptome of winter wheat, whereas the expression profiles of organellar genes were much less responsive to low temperature stress. In total, there were 15,042 nuclear genes with significantly (FDR < 0.05) altered expression profiles caused by exposure to low temperature. From this number, a total of 2,466 genes had a substantially (log2 FC > 2 or log2 FC < -2) affected expression profile. The highest number of upregulated genes was observed from chromosomes in homoeologous group 5, followed by group 2. Differentially expressed genes (DEGs) with the most extreme upregulation encompassed CBFIIId-12.1, WRKY transcription factor 55-like, and a group of genes related to jasmonate signalling pathway. [ABSTRACT FROM AUTHOR]

Summary: Arabidopsis thaliana AKR2A plays an important role in plant responses to cold stress. However, its exact function in plant resistance to cold stress remains unclear. In the present study, we found that the contents of very long‐chain fatty acids (VLCFAs) in akr2a mutants were decreased, and the expression level of KCS1 was also reduced. Overexpression of KCS1 in the akr2a mutants could enhance VLCFAs contents and chilling tolerance. Yeast‐2‐hybrid and bimolecular fluorescence complementation (BIFC) results showed that the transmembrane motif of KCS1 interacts with the PEST motif of AKR2A both in vitro and in vivo. Overexpression of KCS1 in akr2a mutants rescued akr2a mutant phenotypes, including chilling sensitivity and a decrease of VLCFAs contents. Moreover, the transgenic plants co‐overexpressing AKR2A and KCS1 exhibited a greater chilling tolerance than the plants overexpressing AKR2A or KCS1 alone, as well as the wild‐type. AKR2A knockdown and kcs1 knockout mutants showed the worst performance under chilling conditions. These results indicate that AKR2A is involved in chilling tolerance via an interaction with KCS1 to affect VLCFA biosynthesis in Arabidopsis. Significance Statement: AKR2A is positively involved in chilling tolerance by interacting with KCS1 to regulate VLCFA biosynthesis in Arabidopsis. [ABSTRACT FROM AUTHOR]

Tomato (Lycopersicon esculentum Mill [ Solanum lycopersicum L.].) is an important food material and cash crop, as well as a model plant for genetic evolution and molecular biology research. However, as a cold-sensitive crop originating from the tropics, the growth and development of tomato is often affected by low temperature stress. Therefore, how processing tomatoes resist this type of stress has important theoretical and practical significance. In this study, the LeCOLD1 gene was cloned from processing tomato. Subcellular localization analysis showed that LeCOLD1 was located in the plasma membrane. Real-time quantitative PCR analysis showed that LeCOLD1 was highly expressed in roots. Drought, salt and low temperatures induced the expression of COLD1. Overexpression and RNA interference vectors of LeCOLD1 were constructed and were transformed into tomato by the Agrobacterium-mediated method, and then obtaining transgenic tomato plants. It was found that LeCOLD1 increased the height of processing tomato plants and increased the length of their roots. In addition, overexpression of LeCOLD1 significantly improved the cold resistance of the plants. Overexpressing LeCOLD1 in tomato plants reduced the damage to the cell membrane, accumulation of ROS and photoinhibition of PSII, and maintained the high activity of antioxidant enzymes and the content of osmotic regulators. Further analysis revealed that during low temperature stress, the cells maintained high levels of antioxidant enzyme activity by regulating the transcription of the genes encoding these enzymes. The results show that overexpressing LeCOLD1 in tomato increases the plants' resistance to low temperatures, and that reducing LeCOLD1 expression makes the plants more sensitive to low temperatures. • Overexpression of LeCOLD1 enhances the cold tolerance of transgenic tomato plants. • LeCOLD1 overexpression decreases membrane damage and the production of reactive oxygen species. • LeCOLD1 overexpression increases the levels of osmotic regulators and the activities of antioxidant enzymes. • Suppression of LeCOLD1 by RNAi decreases the cold tolerance of tomato plants. [ABSTRACT FROM AUTHOR]

Background: Sheepgrass (Leymus chinensis (Trin.) Tzvel) is a perennial forage grass that can survive extreme freezing winters (− 47.5 °C) in China. In this study, we isolated an unknown function MYB transcription factor gene, LcMYB4, from sheepgrass. However, the function of LcMYB4 and its homologous genes has not been studied in other plants. Results: The expression of the LcMYB4 gene was upregulated in response to cold induction, and the LcMYB4 fusion protein was localized in the nucleus, with transcriptional activation activity. Biological function analysis showed that compared with WT plants, LcMYB4-overexpressing Arabidopsis presented significantly increased chilling and freezing tolerance as evidenced by increased germination rate, survival rate, and seed setting rate under conditions of low temperature stress. Furthermore, LcMYB4-overexpressing plants showed increased soluble sugar content, leaf chlorophyll content and superoxide dismutase activity but decreased malondialdehyde (MDA) under chilling stress. Moreover, the expression of the CBF1, KIN1, KIN2 and RCI2A genes were significantly upregulated in transgenic plants with chilling treatment. These results suggest that LcMYB4 overexpression increased the soluble sugar content and cold-inducible gene expression and alleviated oxidative damage and membrane damage, resulting in enhanced cold resistance in transgenic plants. Interestingly, our results showed that the LcMYB4 protein interacts with fructose-1,6-bisphosphate aldolase protein1 (LcFBA1) and that the expression of the LcFBA1 gene was also upregulated during cold induction in sheepgrass, similar to LcMYB4. Conclusion: Our findings suggest that LcMYB4 encodes MYB transcription factor that plays a positive regulatory role in cold stress. [ABSTRACT FROM AUTHOR]

The sucrose non-fermenting-1 related protein kinase 2 (SnRK2) family plays an important role in the response to abiotic stress. To characterize the function of the SnRK2 gene from Agropyron cristatum in stress protection, we cloned the complete coding sequence of the AcSnRK2.11 gene from A. cristatum and generated AcSnRK2.11-overexpressing tobacco lines. The open reading frame of AcSnRK2.11 was 1083 bp in length and encoded a polypeptide of 360 amino acid residues. The sequence analysis results showed that AcSnRK2.11 contained conserved domains typified in SnRK2 protein kinases. Subcellular localization analysis showed that AcSnRK2.11 was located in the nucleus. AcSnRK2.11 was constitutively expressed in all of the examined tissues, and its transcription was induced by cold, dehydration, and salt stress, but not by abscisic acid treatment. Overexpression of the AcSnRK2.11 gene conferred freezing tolerance in yeast. AcSnRK2.11-overexpressing tobacco lines showed higher tolerance to freezing stress than did wild-type (WT) based on higher survival rates, lower malondialdehyde content and increased relative water content retention, chlorophyll yields, superoxide dismutase activities, reactive oxygen species content, peroxidase levels, and soluble carbohydrates under low-temperature conditions. The transcripts of NtDREB1, NtDREB2, NtERD10A, NtERD10B, NtERD10C, NtERD10D, NtMnSOD, NtCDPK15, and NtMPK9 in AcSnRK2.11-overexpressing tobacco lines were more abundant than in WT plants under low-temperature stress. These results suggest that AcSnRK2.11 may function as a regulatory factor associated with a cold-response pathway and could be used in plant breeding for cold resistance. [ABSTRACT FROM AUTHOR]

[Objective] This paper aimed to provide a reference for the further study of rice C24-sterol methyltransferase 2(OsSMT2)gene. [Method]The physicochemical properties, structural characteristics, enrichment analysis of co-expressed genes, cis-acting elements of promoters and expression patterns of OsSMT2 were analyzed. [Result] The CDs of OsSMT2 gene was 1092 bp, encoding a protein of 363 amino acid with a methyltransferase domain and a C-terminal sterol methyltransferase domain. The OsSMT2 gene contained no signal peptide, and had a transmembrane domain. GO and KEGG Pathway Enrichment Analysis showed that the co-expressed genes of OsSMT2 were mainly enriched in the process of DNA replication and biosynthesis of secondary metabolites. Analysis of the promoter cis-elements revealed that the OsSMT2 maight be involved in the cold and drought resistance in plants. Expression pattern analysis showed that OsSMT2 had the highest expression in the germinated seeds and the lowest expression in the leaves. [Conclusion] OsSMT2 is mainly expressed in germinated seeds, radicle and germ, and participates mainly in the process of rice DNA replication and cell division. It can be used as a candidate gene for rice cold-resistant and drought-resistant breeding. [ABSTRACT FROM AUTHOR]

Frost stress severely affects agriculture and agroforestry worldwide. Although many studies about frost hardening and resistance have been published, most of them focused on the aboveground organs and only a minority specifically targets the roots. However, roots and aboveground tissues have different physiologies and stress response mechanisms. Climate models predict an increase in the magnitude and frequency of late-frost events, which, together with an observed loss of soil insulation, will greatly decrease plant primary production due to damage at the root level. Molecular and metabolic responses inducing root cold hardiness are complex. They involve a variety of processes related to modifications in cell wall composition, maintenance of the cellular homeostasis and the synthesis of primary and secondary metabolites. After a summary of the current climatic models, this review details the specificity of freezing stress at the root level and explores the strategies roots developed to cope with freezing stress. We then describe the level to which roots can be frost hardy, depending on their age, size category and species. After that, we compare the environmental signals inducing cold acclimation and frost hardening in the roots and aboveground organs. Subsequently, we discuss how roots sense cold at a cellular level and briefly describe the following signal transduction pathway, which leads to molecular and metabolic responses associated with frost hardening. Finally, the current options available to increase root frost tolerance are explored and promising lines of future research are discussed. [ABSTRACT FROM AUTHOR]