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Tick-borne severe fever with thrombocytopenia syndrome (SFTS) is an emerging zoonotic disease caused by the SFTS virus (SFTSV). Serological assays based on the nucleocapsid protein and partial glycoprotein of this virus have been used for detecting SFTSV infections in humans and animals. However, whether the complete SFTSV glycoprotein (Gn/Gc) can induce the assembly of virus-like particles (VLPs) which can be used for serological surveillance and vaccine production remains unclear. In this study, we successfully expressed and secreted SFTSV Gn/Gc antigens by using a single plasmid encoding the complete glycoprotein sequence of the dominant genotype B virus. HEK293T and COS-1 cells were transfected with the aforementioned plasmid; cultivating these cells at 32 °C, instead of 37 °C, led to 4.0- and 3.3-fold higher antigen recovery, respectively. The secreted Gn/Gc antigens at 32 °C retained epitopes resembling those of the virion; these epitopes were recognized by a SFTS human–derived monoclonal antibody. Sucrose density gradient centrifugation, followed by transmission electron microscopy, confirmed the formation of VLPs with a diameter of approximately 100 nm. Overall, our findings highlight the potential of SFTSV VLPs for serological surveillance and vaccine development. Key points •  Cultivating transfected cells at 32 °C boosts SFTSV glycoprotein production. •  Complete SFTSV glycoprotein expression facilitates virus-like particle assembly. •  The assembly does not require any other viral proteins or RNA.

The influence of climatic factors, e.g., low temperature, on the phytochemical composition and bioactivity of the arctic plant Dracocephalum palmatum Steph. ax Willd. (palmate dragonhead), a traditional food and medical herb of Northern Siberia, was investigated. D. palmatum seedlings were grown in a greenhouse experiment at normal (20 °C, NT) and low (1 °C, LT) temperature levels and five groups of components that were lipophilic and hydrophilic in nature were characterized. The analyses indicated that D. palmatum under NT demonstrates high content of photosynthetic pigments, specific fatty acid (FA) profile with domination of saturated FA (53.3%) and the essential oil with trans-pinocamphone as a main component (37.9%). Phenolic compounds were identified using a combination of high performance liquid chromatography with diode array detection and electrospray ionization mass-spectrometric detection (HPLC-DAD-ESI-MS) techniques, as well as free carbohydrates and water soluble polysaccharides. For the first time, it was established that the cold acclimation of D. palmatum seedlings resulted in various changes in physiological and biochemical parameters such as membrane permeability, photosynthetic potential, membrane fluidity, leaf surface secretory function, reactive oxygen species–antioxidant balance, osmoregulator content and cell wall polymers. In brief, results showed that the adaptive strategy of D. palmatum under LT was realized on the accumulation of membrane or surface components with more fluid properties (unsaturated FA and essential oils), antioxidants (phenolic compounds and enzymes), osmoprotectants (free sugars) and cell wall components (polysaccharides). In addition, the occurrence of unusual flavonoids including two new isomeric malonyl esters of eriodictyol-7-O-glucoside was found in LT samples. Data thus obtained allow improving our understanding of ecophysiological mechanisms of cold adaptation of arctic plants.

Overexpression and production of the high concentration of hydroxynitrile lyase from cassava (Manihot esculenta (MeHNL, EC 4.1.2.39)) were investigated. Hydroxynitrile lyase is a useful enzyme for the production of optically active cyanohydrin compounds. The production of MeHNL was increased by changing the rare codons of the original sequence of cassava MeHNL. However, most of the produced MeHNL was in the insoluble form. In order to increase the solubility of MeHNL, the effects of the cultivation temperature were investigated. When the cultivation temperature was reduced, the cell yield and the ratio of soluble MeHNL increased significantly. The enzyme activity and yield at low-temperature cultures (17 °C) were 850 times higher than those obtained at the optimum growth temperature of 37 °C. The rate of MeHNL production in the present study was calculated as 3,000 unit/h. Low-temperature cultivation was very effective in improving the productivity of the active form of MeHNL. Unlike the temperature-shift method, low-temperature cultivation has more potential for the large-scale production of MeHNL for the optically active cyanohydrin production.

Background Abiotic stresses have increasingly serious effects on the growth and yield of crops. Cold stress, in particular, is an increasing problem. In this study, Fragaria daltoniana and F. vesca were determined to be cold-resistant and cold-sensitive species, respectively. Integrated transcriptomics and metabolomics methods were used to analyze the regulatory mechanism of abscisic acid (ABA) in F. daltoniana and F. vesca in their response to low temperature stress. Results F. daltoniana and F. vesca increased their ABA content under low temperature stress by upregulating the expression of the ABA biosynthetic pathway gene NCED and downregulating the expression of the ABA degradative gene CYP707A . Both types of regulation increased the accumulation of glucose and fructose, resulting in a reduction of damage under low temperature stress. Twelve transcription factors were found to be involved in the ABA regulatory pathway. The strong cold tolerance of F. daltoniana could be owing to its higher levels of ABA that accumulated compared with those in F. vesca under low temperature stress. In addition, the gene ABF2 , which is related to the transduction of glucose signaling, was significantly upregulated in the leaves of F. daltoniana , while it was downregulated in the leaves of F. vesca under low temperature stress. This could contribute to the higher levels of glucose signal transduction in F. daltoniana . Thus, this could explain the higher peroxidase activity and lower damage to cell membranes in the leaves of F. daltoniana compared with F. vesca under low temperature stress, which endows the former with stronger cold tolerance. Conclusions Under low temperature stress, the differences in the accumulation of ABA and the expression trends of ABF2 and ABF4 in different species of wild strawberries may be the primary reason for their differences in cold tolerance. Our results provide an important empirical reference and technical support for breeding resistant cultivated strawberry plants.

Environmental stress conditions such as drought, heat, salinity, cold, or pathogen infection can have a devastating impact on plant growth and yield under field conditions. Nevertheless, the effects of these stresses on plants are typically being studied under controlled growth conditions in the laboratory. The field environment is very different from the controlled conditions used in laboratory studies, and often involves the simultaneous exposure of plants to more than one abiotic and/or biotic stress condition, such as a combination of drought and heat, drought and cold, salinity and heat, or any of the major abiotic stresses combined with pathogen infection. Recent studies have revealed that the response of plants to combinations of two or more stress conditions is unique and cannot be directly extrapolated from the response of plants to each of the different stresses applied individually. Moreover, the simultaneous occurrence of different stresses results in a high degree of complexity in plant responses, as the responses to the combined stresses are largely controlled by different, and sometimes opposing, signaling pathways that may interact and inhibit each other. In this review, we will provide an update on recent studies focusing on the response of plants to a combination of different stresses. In particular, we will address how different stress responses are integrated and how they impact plant growth and physiological traits.

Background Heilongjiang Province has a long and cold winter season (the minimum temperature can reach -30 ℃), and few winter wheat varieties can safely overwinter. Dongnongdongmai1 ( Dn1 ) is the first winter wheat variety that can safely overwinter in Heilongjiang Province. This variety fills the gap for winter wheat cultivation in the frigid region of China and greatly increases the land utilization rate. To understand the molecular mechanism of the cold response, we conducted RNA-sequencing analysis of Dn1 under cold stress. Results Approximately 120,000 genes were detected in Dn1 under cold stress. The numbers of differentially expressed genes (DEGs) in the six comparison groups (0 ℃ vs. 5 ℃, -5 ℃ vs. 5 ℃, -10 ℃ vs. 5 ℃, -15 ℃ vs. 5 ℃, -20 ℃ vs. 5 ℃ and -25 ℃ vs. 5 ℃) were 11,313, 8313, 15,636, 13,671, 14,294 and 13,979, respectively. Gene Ontology functional annotation suggested that the DEGs under cold stress mainly had “binding”, “protein kinase” and “catalytic” activities and were involved in “oxidation–reduction”, “protein phosphorylation” and “carbohydrate metabolic” processes. Kyoto Encyclopedia of Genes and Genomes enrichment analysis indicated that the DEGs performed important functions in cold signal transduction and carbohydrate metabolism. In addition, major transcription factors (AP2/ERF, bZIP, NAC, WRKY, bHLH and MYB) participating in the Dn1 cold stress response were activated by low temperature. Conclusion This is the first study to explore the Dn1 transcriptome under cold stress. Our study comprehensively analysed the key genes involved in cold signal transduction and carbohydrate metabolism in Dn1 under cold stress. The results obtained by transcriptome analysis could help to further explore the cold resistance mechanism of Dn1 and provide basis for breeding of cold-resistant crops. Highlights • Approximately 120,000 genes were detected in Dn1 during the overwintering stage (the lowest sampling temperature was -25 °C), of which 31,000 genes were differentially expressed. • A total of 1230 differentially expressed genes involved in cold signal perception and transduction were detected in Dn1 during the overwintering stage. • A total of 1715 differentially expressed genes involved in carbohydrate metabolism were detected in Dn1 during the overwintering stage, most of which were enriched in glycolysis/gluconeogenesis and starch and sucrose metabolism.

Rice is a major food crop in the world. Owing to the shortage of rural labor and the development of agricultural mechanization, direct seeding has become the main method of rice cultivation. At present, the main problems faced by direct seeding of rice are low whole seedling rate, serious weeds, and easy lodging of rice in the middle and late stages of growth. Along with the rapid development of functional genomics, the functions of a large number of genes have been confirmed, including seed vigor, low-temperature tolerance germination, low oxygen tolerance growth, early seedling vigor, early root vigor, resistance to lodging, and other functional genes related to the direct seeding of rice. A review of the related functional genes has not yet been reported. In this study, the genes related to direct seeding of rice are summarized to comprehensively understand the genetic basis and mechanism of action in direct seeding of rice and to lay the foundation for further basic theoretical research and breeding application research in direct seeding of rice.

Cytokinin Response Factors (CRFs) play a crucial role in plant growth and development, hormone signaling, and responses to biotic and abiotic stresses. However, there have been no reports on CRF genes in rice until now. We analyzed the CRF families in four rice subspecies: cultivated rice Oryza sativa Japonica Group, Oryza sativa Indica Group, and Oryza sativa (circum-Aus1 var. N22), as well as wild rice Oryza rufipogon . We identified 7, 6, 6, and 7 CRF in their genomes, respectively, distributed across different chromosomes. The protein motifs and gene structures of CRF in these four types of rice show high conservation. Cis-regulatory element analysis revealed that the promoter regions of the CRF contain numerous hormone and stress-related elements. The number of CRF in these four types of rice is not influenced by gene duplication. The expression pattern showed that OsCRF exhibit significant tissue-specific expression. The qRT-PCR results showed that OsCRF strongly responded to low-temperature stress and can be induced by melatonin and cytokinin to increase expression levels. In addition, the nuclear localisation of OsCRF4/5 was confirmed to be as predicted. The results above will provide a foundation for further and deeper investigation of CRFs.

Background The cultivation of bananas encounters substantial obstacles, particularly due to the detrimental effects of cold stress on their growth and productivity. A potential remedy that has gained attention is the utilization of ethyl mesylate (EMS)-induced mutagenesis technology, which enables the creation of a genetically varied group of banana mutants. This complex procedure entails subjecting the mutants to further stress screening utilizing L-Hyp in order to identify those exhibiting improved resistance to cold. This study conducted a comprehensive optimization of the screening conditions for EMS mutagenesis and L-Hyp, resulting in the identification of the mutant cm784 , which exhibited remarkable cold resistance. Subsequent investigations further elucidated the physiological and transcriptomic responses of cm784 to low-temperature stress. Results EMS mutagenesis had a substantial effect on banana seedlings, resulting in modifications in shoot and root traits, wherein a majority of seedlings exhibited delayed differentiation and limited elongation. Notably, mutant leaves displayed altered biomass composition, with starch content exhibiting the most pronounced variation. The application of L-Hyp pressure selection aided in the identification of cold-resistant mutants among seedling-lethal phenotypes. The mutant cm784 demonstrated enhanced cold resistance, as evidenced by improved survival rates and reduced symptoms of chilling injury. Physiological analyses demonstrated heightened activities of antioxidant enzymes and increased proline production in cm784 when subjected to cold stress. Transcriptome analysis unveiled 946 genes that were differentially expressed in cm784 , with a notable enrichment in categories related to ‘Carbohydrate transport and metabolism’ and ‘Secondary metabolites biosynthesis, transport, and catabolism’. Conclusion The present findings provide insights into the molecular mechanisms that contribute to the heightened cold resistance observed in banana mutants. These mechanisms encompass enhanced carbohydrate metabolism and secondary metabolite biosynthesis, thereby emphasizing the adaptive strategies employed to mitigate the detrimental effects induced by cold stress.

Rapid and uniform germination of seeds and subsequent high survivability of seedlings in low-temperature environments are two key requirements in the direct-seeding agronomic production system in rice. Dongxiang wild rice (DXWR), the northernmost common wild rice, possesses a number of seedling cold-tolerance loci and is an invaluable genetic resource for the molecular breeding of cold-tolerant rice. However, DXWR has a delayed and desynchronized germination trait in low-temperature environments that is favorable for its adaption to cold environments but is a disadvantage for seedling establishment in the direct-seeding system when integrated into elite cultivars. In the present study, we identified five quantitative trait loci (QTLs) for low-temperature germination in DXWR. All the DXWR alleles delay the germination of DXWR seeds in low-temperature environments. By the pyramiding of QTLs of rapid germination from cultivated rice and QTLs of seedling cold tolerance from high tolerance wild rice DXWR, we obtained a variety numbered DX71 with rapid and uniform germination of seeds and high cold tolerance of seedlings in low-temperature environments. The results could facilitate the understanding of the genetic basis of delayed germination in DXWR, partly explaining how DXWR adapts to low temperatures in its habitat. The identified QTLs provide tightly linked markers for rice breeding in the development of climate-resilient varieties with low input.