Low-temperature Treatment Research Articles

Genome-wide identification of RNA recognition motif (RRM1) in Brassica rapa and functional analysis of RNA-binding protein (BrRBP) under low-temperature stress

BackgroundThe RNA recognition motif (RRM) is primarily engaged in the processing of mRNA and rRNA following gene transcription as well as the regulation of RNA transport; it is critical in preserving RNA stability.ResultsIn this study, we identified 102 members of the RRM1 gene family in Brassica rapa, which were dispersed across 10 chromosomes with the ninth chromosome being the most extensively distributed. The RRM1 gene family members of Brassica rapa and Arabidopsis thaliana were grouped into 14 subclades (I–XIV) using phylogenetic analysis. Moreover, the results of transcriptome analysis and RT-qPCR indicated that the expression of Brapa05T000840 was upregulated in the cultivars ‘Longyou 7’ and ‘Longyou 99’ following exposure to cold stress at a temperature of 4 °C for 24 h. The levels of expression in the leaves and growth cones of the ‘Longyou 7’ variety were found to be significantly higher than those observed in the ‘Longyou 99’ variety under conditions of low temperature and NaCl stress. It illustrates the involvement of the RRM1 gene in the physiological response to both low temperature and salt stress. In addition, it was observed that the survival rate of transgenic BrRBP (Brapa05T000840) Arabidopsis thaliana plants was notably higher compared to that of wild-type plants when subjected to varying durations of low temperature treatment. Furthermore, the expression of the BrRBP gene in transgenic plants exhibited an upward trend as the duration of low temperature treatment increased, reaching its peak at 24 h. The in-vivo enzymatic activity of reactive oxygen species-scavenging enzymes were found to be significantly elevated in comparison to wild-type plants, suggesting that the BrRBP gene may enhance the cold tolerance of Arabidopsis thaliana.ConclusionsThis study offers a significant foundation for comprehending the regulation mechanism of the RRM1 gene family in winter Brassica rapa subjected to cold stress, as well as for finding key genes associated with cold resistance.

Anisotropic Electronic Skin for Neurofeedback

AbstractNeurofeedback training based on brain rhythm is appealing for both cognitive neuroscience and disorder treatment. However, electrodes that can integrate dual functions of recording and feedback without signal compromise still lack. Herein, an anisotropic cellulose carbon sponge (CCS) electrode by tailoring conductivity through the temperature that has the dual ability to record electrophysiological signals and sense pressures as feedback is developed. The electrode is fabricated via a gradient temperature annealing on CCS, which involves lower (300 °C) and higher (1000 °C) temperature treatments, namely CCS‐LT and CCS‐HT. CCS‐LT exhibits perpendicular resilience to the alignment direction of CCS, and CCS‐HT possesses lower sheet resistance (≈13 Ω sq−1) parallel to the alignment direction. As a pressure sensor, CCS‐LT can achieve excellent sensitivity (1.04 kPa−1), fast response time (27 ms), and reliable stability for 1000 cycles. CCS‐HT can serve as skin electrodes for electrophysiological sensing. The anisotropic functionality of annealed CCS allows it to be used in one sensing and regulation closed‐loop system driven by nerves, achieving accurate acquisition of human brain rhythm and machine movement information simultaneously. This not only helps rapid tracking of brain activity but also facilitates feedback regulation to enhance human brain function, having great potential applications in neurofeedback and disease rehabilitation.

Transcription factor OsMYB30 increases trehalose content to inhibit α-amylase and seed germination at low temperature.

Low-temperature germination (LTG) is an important agronomic trait for direct-seeding cultivation of rice (Oryza sativa). Both OsMYB30 and OsTPP1 regulate the cold stress response in rice, but the function of OsMYB30 and OsTPP1 in regulating LTG and the underlying molecular mechanism remains unknown. Employing transcriptomics and functional studies revealed a sugar signaling pathway that regulates seed germination in response to low temperature (LT). Expression of OsMYB30 and OsTPP1 was induced by LT during seed germination, and overexpressing either OsMYB30 or OsTPP1 delayed seed germination and increased sensitivity to LT during seed germination. Transcriptomics and qPCR revealed that expression of OsTPP1 was upregulated in OsMYB30-overexpressing lines but downregulated in OsMYB30-knockout lines. In vitro and in vivo experiments revealed that OsMYB30 bound to the promoter of OsTPP1 and regulated the abundance of OsTPP1 transcripts. Overaccumulation of trehalose (Tre) was found in both OsMYB30- and OsTPP1-overexpressing lines, resulting in inhibition of α-amylase 1a (OsAMY1a) gene during seed germination. Both LT and exogenous Tre treatments suppressed the expression of OsAMY1a, and the osamy1a mutant was not sensitive to exogenous Tre during seed germination. Overall, we concluded that OsMYB30 expression was induced by LT to activate the expression of OsTPP1 and increase Tre content, which thus inhibited α-amylase activity and seed germination. This study identified a phytohormone-independent pathway that integrates environmental cues with internal factors to control seed germination.

Supply Chain and Quality Analysis of Frozen Scad Mackerel (Decapterus spp.) As Raw Material for Pindang Processing in Pekalongan Regency, Indonesia

Scad mackerel (Decapterus spp.) has a high nutritional content but is susceptible to spoilage. As the main raw material for Indonesian salted-boiled fish (Pindang) processing, the quality of frozen Scad mackerel (Decapterus spp.) plays an important role that will affect product quality and customer acceptance. Low-temperature storage treatment still has the potential for deterioration of fish quality. This research is a descriptive study conducted in Pekalongan Regency and City during May 2023 to identify the supply chain structure and the quality and safety of frozen mackerel (Decapterus spp.) as raw material for pindang production. The results showed that the parties that play a role in the supply chain of fish raw materials in the pindang processing business in Pekalongan Regency are fishermen, Pekalongan Municipal Fish Auction Center, Fish Middlemen, retailers and pindang processors. At the level of Fish Middlemen up to the pindang fish processing unit, no documentation can describe the handling and origin of the fish. The quality and safety testing of frozen scad mackerel (Decapterus spp.) includes the Sensory Test, TVB-N Test, Total Plate Count (TPC) Test and Escherichia coli Test. The sensory test results showed that all samples were above 7, the average value of TVB-N test results was 17.84 mgN/100mg, the average value of TPC test results was 5x103 colonies/g, and the average value of Escherichia coli test results was <3 MPN/g. Tests of frozen Scad mackerel samples showed that the fish was of good quality and free from harmful preservatives (formalin), making it safe to use as raw material in the pindang processing.

Effects of hot air-assisted radio frequency stabilization of brown millet and millet bran: Enzyme inactivation, microstructure, nutritional quality, and storage stability

Brown millet (BM) and millet bran (MB) are rich sources of nutrients, but their storage is affected by rapid rancidity deterioration, which primarily due to the activity of lipase (LA) and peroxidase (POD). High moisture content and water activity also have adverse effects on rancidity. In order to inactivate enzyme activities and extend storage stability of BM and MB, hot air-assisted radio frequency (HA-RF) heating was applied in this study. BM was treated at 95 °C and 105 °C while MB was heated to 105 °C and 115 °C with various holding times. The effects on enzyme inactivation, microstructure, nutritional quality, and storage stability of the samples were investigated. The results showed that HA-RF treatment effectively reduced LA and POD activities in both BM (<13%) and MB (<10%); Low-temperature (95 °C for BM and 105 °C for MB) HA-RF treatment caused less damage to the structure of the samples and maintained the structural integrity of most starch and proteins, although the treatment significantly (p < 0.05) reduced free phenolic and flavonoid contents of the samples; Low-temperature HA-RF treatment had less impacts on main nutrients of BM and MB when compared to the high-temperature treatment (105 °C for BM and 115 °C for MB). HA-RF stabilization effectively improved the storage stability, and slowed down the increase in fatty acid value (FAV) and malondialdehyde (MDA) content during storage.

Thermal Stability of Electrodeposited Fe-55wt%Ni Alloy and Effect of Low-Temperature Heat Treatment on Magnetic Properties

Electrodeposited nanocrystalline soft magnetic materials have emerged as one of the hottest research topics in the field of magnetic materials due to they are easy to implement in miniaturization, lightweight, and energy-saving of electronic devices. The thermal stability and grain growth process of electrodeposited Fe-55wt%Ni alloy were investigated. Results indicated that the grain growth was rapid at a temperature of about 678 K, while the exothermic peak appeared in DSC with an exothermic heat of about 12 ± 1 J g−1. The activation energy for grain growth was obtained through the optimized Kissinger equation and isothermal kinetics calculations, and the growth mechanism was evaluated based on the calculation results. Below 678 K, the activation energy required for grain growth was low, which implied the growth mechanism was the rearrangement of atoms at the grain boundary; Above 678 K, the growth mechanism was grain boundary diffusion. After the low-temperature heat treatment, the coercivity (H c) decreased and the saturation magnetization (M s) increased slightly, which was attributed to the reduction of internal stress and the ultra-fine nanocrystalline structure. The optimal heat treatment process was 573 K heat treatment for 5 h, where M s and H c of 160 emu g−1 and below 1 Oe, respectively.

Effectiveness of Calcium Alginate Dressing in Combination with Nasal Endoscopic Bipolar Electrocoagulation and Low-Temperature Plasma Knife Treatment on Bleeding Volume, Nasal Ventilation, Stress Response, and Recurrence Rate in Patients with Refractory Epistaxis

The aim of this study was to compare the effects of nasal endoscopic bipolar electrocoagulation (BE) and low-temperature plasma knife (LPK) treatment on intractable epistaxis (IE) in order to provide a reference and guidance for future treatment options for IE. A total of 109 patients with IE admitted to Dongying People’s Hospital from June 2021 to May 2022 were selected for the study. Of these, 58 were treated with BE (BE group) and 51 were treated with LPK (LPK group). The nasal cavities of patients in the BE and LPK groups were filled with a gelatin sponge and calcium alginate dressing, respectively, after surgery. The clinical efficacy, operation time, hemostasis time, and intraoperative bleeding volume of the two groups were compared. Patients’ unilateral inspiratory resistance (IR), expiratory resistance (ER), bilateral total inspiratory resistance (TIR), and total expiratory resistance (TER) were measured using a nasal resistance tester, and pain was assessed using a visual analog scale (VAS). Serum epinephrine (E), norepinephrine (NE), and cortisol (Cor) levels were also measured in patients before and after surgery, and complications were recorded. The recurrence of IE was measured at a 6-month follow-up after discharge from the hospital. There were no differences in clinical efficacy, hemostasis time, or intraoperative bleeding between groups (P &gt;0.05), and the operative time was longer in both BE groups (P &lt;0.05). In addition, postoperative IR, ER, TIR, and TER were higher in the BE group than in the LPK group, and the VAS score results were also higher at 1 d postoperatively (P &lt;0.05). After surgery, E, NE, and Cor were elevated in both groups; more so in the BE group than in the LPK group (P &lt;0.05). Differences in the incidence of complications and prognostic recurrence rates between groups were not statistically significant (P &gt;0.05).

Tribological performance of low-temperature plasma carburized AISI 420 martensitic stainless steel

Plasma carburizing has emerged as a potent technique for improving the wear resistance of stainless steels, and sustaining or improving corrosion resistance through a suitable choice of process parameters. This study evaluated the impact of plasma carburizing time and temperature on the tribological behavior of AISI 420 martensitic stainless steel through dry-sliding wear tests in a ball-on-disk configuration. Two different treatment sets were conducted to assess the impact of carburizing time and temperature on the wear performance of the treated AISI 420 steel. The first group encompassed treatments at temperatures spanning from 350 to 500 °C, with fixed treatment times of 8 and 12 h. The second group involved treatments at a temperature of 400 °C for durations spanning 12 to 48 h and at temperature of 450 °C for durations between 4 and 16 h. To facilitate the discussion of wear test results, microstructural analysis was performed using metallographic analysis, X-ray diffraction, and microscale hardness measurements. Microstructural characterization results revealed that the carburized surface consists of an outer layer followed by a diffusion layer. The diffusion layer is primarily composed of the α′C phase, while the outer layer contains α′C and Fe3C (for low-temperature and short-time treatments) and Cr/Fe-carbides primarily formed due to the α′C decomposition into Fe–α phase (for the studied higher-temperature and longer-time treatments). Wear test results suggest that the surface structure and composition of the treated material exert substantial influence on its tribological behavior. Carburized layers free from Cr-carbide precipitation exhibit lower wear and friction coefficients. The decomposition of α′C into Fe-α and Cr/Fe-carbides leads to an elevation of friction and wear coefficients. Finally, carbon enrichment does not alter the wear mechanism, as both uncarburized and carburized samples exhibited microabrasion and oxidative wear.

Elucidating influences of defects and thermal treatments on CO2 capture of a Zr-based metal–organic framework

Carbon capture and storage (CCS) technology is currently an essential response to the global warming problem caused by excessive CO2 emissions. Efficient and reproducible adsorbents for flue gas treatment play an important role in CCS technology, and metal–organic frameworks (MOFs) are considered to be ideal candidates by virtue of their designable CO2 sorption sites. However, carbon capture performance evaluation and reproducibility of MOFs still hinder their application promotion in industrial production. In this work, an extended UiO-66-type MOF based on 1,4-naphthalenedicarboxylate, was successfully synthesized in both a near defect-free form (UiO-66N) and a defect-rich form (DUiO-66N), for exploring the influence of crystalline defects and thermal treatments on carbon capture performance. Although powder X-ray diffraction showed that UiO-66N and DUiO-66N possessed the same crystalline phase, transmission electron microscopy, thermalgravimetric analyse and gas/dye sorption confirmed the presence of crystalline defects and the variation of porosity in DUiO-66N. CO2 sorption isotherms and flue gas breakthrough experiments revealed the defect-induced improved carbon capture performance, which was also supported by density functional theory. Meanwhile, the metastability of defects required low thermal treatment temperatures for activation and regeneration thus maintaining the superior carbon capture performance. These findings suggested that in reproducing and evaluating the carbon capture performance of MOFs, it cannot rely only on the global crystalline phase judgment, but needs to identify the local fine structure as well as optimize activation and regeneration conditions.

PTFE nanofiber cross-linked acetylene black: A flexible self-supporting semi-confined architecture for ultra-high sulfur loading and areal capacity

Lithium-sulfur batteries attract great interest due to their high energy density, sulfur abundance and environment friendly. However, the shuttle effect of lithium polysulfide and serious capacity fading especially at high sulfur loading remains a challenge for their commercial applications. In this work, we propose a scalable and feasible strategy to construct a flexible host for sulfur and catalyst carrier, in which polytetrafluoroethylene is employed as a precursor and in-situ polymerized into nanofibers to link acetylene black (PTFE NF/AB) through a blend and low temperature (∼ 180 °C) treatment process. The PTFE NF/AB exhibits semi-confined architecture for sulfur accommodation, electrolyte infiltration and electron transformation. Impressively, the electrode achieves a high areal capacity of 14.6 mAh cm−2 at the current density of 4.82 mA cm−2 with a sulfur loading of 20.6 mg cm−2. Moreover, the PTFE NF/AB architecture can be employed as the catalyst supports. The capacity can be further enhanced to 17.4 mAh cm−2 when MoS2 fabricated into the PTFE NF/AB using a ball mill approach. Assembled into a pouch cell, the PTFE NF/AB architecture delivers a high capacity of 825.4 mAh g−1 in the folded state, showing its excellent potential in the high-energy flexible territory.

Effects of Plasma Treatment on the Strength of Bonding to Ceramic Surfaces in Orthodontics-A Comprehensive Review.

Over the past several decades, orthodontic treatment has been increasingly sought out by adults, many of whom have undergone restorative dental procedures that cover enamel. Because the characteristics of restorative materials differ from those of enamel, typical bonding techniques do not yield excellent restoration-bracket bonding strengths. Plasma treatment is an emerging surface treatment that could potentially improve bonding properties. The purpose of this paper is to evaluate currently available studies assessing the effect of plasma treatment on the shear bond strength (SBS) and failure mode of resin cement/composite on the surface of ceramic materials. PubMed and Google Scholar databases were searched for relevant studies, which were categorized by restorative material and plasma treatment types that were evaluated. It was determined that cold atmospheric plasma (CAP) treatment using helium and H2O gas was effective at raising the SBS of feldspathic porcelain to a bonding agent, while CAP treatment using helium gas might also be a potential treatment method for zirconia and other types of ceramics. More importantly, CAP treatment using helium has the potential for being carried out chairside due to its non-toxicity, low temperature, and short treatment time. However, because all the studies were conducted in vitro and not tested in an orthodontic setting, further research must be conducted to ascertain the effectiveness of specific plasma treatments in comparison to current orthodontic bonding treatments in vivo.

Response of CO2 and CH4 emissions from Arctic tundra soils to a multifactorial manipulation of water table, temperature and thaw depth

Significant uncertainties persist concerning how Arctic soil tundra carbon emission responds to environmental changes. In this study, 24 cores were sampled from drier (high centre polygons and rims) and wetter (low centre polygons and troughs) permafrost tundra ecosystems. We examined how soil CO2 and CH4 fluxes responded to laboratory-based manipulations of soil temperature (and associated thaw depth) and water table depth, representing current and projected conditions in the Arctic. Similar soil CO2 respiration rates occurred in both the drier and the wetter sites, suggesting that a significant proportion of soil CO2 emission occurs via anaerobic respiration under water-saturated conditions in these Arctic tundra ecosystems. In the absence of vegetation, soil CO2 respiration rates decreased sharply within the first 7 weeks of the experiment, while CH4 emissions remained stable for the entire 26 weeks of the experiment. These patterns suggest that soil CO2 emission is more related to plant input than CH4 production and emission. The stable and substantial CH4 emission observed over the entire course of the experiment suggests that temperature limitations, rather than labile carbon limitations, play a predominant role in CH4 production in deeper soil layers. This is likely due to the presence of a substantial source of labile carbon in these carbon-rich soils. The small soil temperature difference (a median difference of 1 °C) and a more substantial thaw depth difference (a median difference of 6 cm) between the high and low temperature treatments resulted in a non-significant difference between soil CO2 and CH4 emissions. Although hydrology continued to be the primary factor influencing CH4 emissions, these emissions remained low in the drier ecosystem, even with a water table at the surface. This result suggests the potential absence of a methanogenic microbial community in high-centre polygon and rim ecosystems. Overall, our results suggest that the temperature increases reported for these Arctic regions are not responsible for increases in carbon losses. Instead, it is the changes in hydrology that exert significant control over soil CO2 and CH4 emissions.

Optimizing strength and fatigue crack propagation resistance of in-situ TiB2/Al-Cu-Mg composite sheet

The industrial-grade TiB2/Al-Cu-Mg composite sheet was fabricated via casting and rolling methods. Cold-rolling coupled with low-temperature aging treatment was used to regulate the grain size, dislocation density, precipitates and TiB2 particle distribution, to optimize the strength and fatigue crack propagation (FCP) resistance of the sheet. The results show that pre-rolling deformation combined with low-temperature long-term aging is beneficial for obtaining fine grains, high-density dislocations, high-density nano precipitates and uniform particle distribution, all of which are conducive to improving strength. The TiB2/Al-Cu-Mg composite sheet can achieve remarkable ultimate tensile strength over 600 MPa regardless of its excellent elongation (12 %). Furthermore, uniformly distributed TiB2 particles and high-density nano precipitates are beneficial for offsetting the negative effect of high-density dislocations on FCP. Finally, the small pre-rolling deformation (5 %) combined with low-temperature long-term aging achieves excellent strength and FCP resistance combination.

Chitosan-Pd0 nanoparticles encapsulated in Al, Co-pillared montmorillonite by one-pot process

Chitosan-Pd0 (CS-Pd0) nano particles encapsulated in Al, Co-pillared montmorillonite (MMt) nanocomposites were synthesized by a facile one-pot heat treatment method. The MMt was impregnated with Al, Co pillaring reagent, protonated chitosan solution, and Na2PdCl4 solution, followed with a controlled low-temperature (200 °C) heat treatment, resulting in Pd@CS/Al, Co-MMt nanocomposites. Al, Co pillaring effectively expanded the basal spacing of MMt layers from 1.24 nm to 1.82 nm, and generated numerous mesopores in interlayer space, resulting in increase of surface area from 11.8 m2/g to 198.3 m2/g. Due to the well encapsulation of CS chains in the interlayer nano-spaces, the specific surface area of the hybrid nanocomposite underwent a reasonably decrease as the CS content increase. Most of nano-sized Pd species (2–3 nm) chelated with CS chains dispersed well in the interlayer space of the porous Al, Co pillared MMt matrix. The resultant nanocomposite prepared by such facial one-pot process method have similar high comprehensive catalytic performances as applied in coupling reactions to that prepared by regular divided-multistep method. Moreover, it is confirmed that Al pillaring doped with Co and encapsulation of CS chains have synergistic improving effects on the comprehensive catalytic performance of the nanocomposites.

Physiological responses and quality assessment of turbot (Scophthalmus maximus) during waterless preservation and transportation: Implications for survival and biochemical indicators

In this study, changes in the physiological parameters of the muscles of living turbot (Scophthalmus maximus) fish during waterless preservation and transportation were assessed. Results indicated that the survival rate of turbot at low temperature, waterless conditions in pure O2 was 100% at 24 h and 95% at 36 h. Crude fat, organic acids, free amino acids, ATP levels, and pH values in the fish at 12 h after revitalization were not significantly different (p < 0.05) in the waterless preservation treatment than they were in the control group. Total protein content in turbot meat of recovered fish was close to the content in the control group. Although the protein content was lower than it was in the control group, the difference was negligible. Moreover, the elasticity, chewiness, and viscosity of turbot meat after 12 h of recovery was the same as those attributes in fish in the control group. The low-temperature waterless preservation treatment induced a strong stress response in turbot fish, characterized by strong biochemical reactions that resulted in fluctuations in the level of several stress indicators. Nevertheless, the recovery period provided a partial recovery of the indicator levels. The results of this study will contribute to the development of an effective, eco-friendly method to improve the survival rate and quality of living turbot fish during waterless preservation and transport. The study provides new insights that can be used to improve the waterless preservation and transport of living turbot fish, while addressing both market needs and consumer expectations.

A novel method for layer separation in waste crystalline silicon PV modules via combined low-temperature and thermal treatment

With the significant growth in the production and installation of photovoltaic (PV) systems, the recycling of end-of-life PV modules has become a critical concern. Thermal treatment is a promising approach to decompose all the polymer and separate different layers rapidly. However, the combustion of the backsheet can lead to the release of hazardous fluorinated compounds. This paper proposes a novel method combining low-temperature and thermal treatment to separate different layers in PV modules. This method leverages the back metallization of solar cells for PV module separation, providing a fresh separation perspective. The focus lies on investigating a low-temperature separation process, and the separation interfaces are characterized using SEM and EDS, shedding light on the separation position and physical separation mechanisms. Subsequently, the effects of different freezing temperatures, freezing times, and different laminated parts were investigated, and the processing parameters were optimized. Compared to direct thermal treatment, the proposed process eliminates the generation of hazardous fluorides and mitigates mass losses caused by thermal treatment effectively. This research provides valuable insights into the green and sustainable resource recovery of waste PV modules.

Fabrication of leather-like yarns using waste leather for textile application

The escalating focus on emulating natural textiles has prompted a concurrent surge in research aimed at developing leather-like materials. However, traditional leather products are mostly represented as sheets or blocks, which limit their reprocessing. Therefore, in this study, waste leather scraps were processed into powders with an average particle size of 5–10 μm. Subsequently, these recycled powders were wet-spun alongside a polyurethane matrix and polyester yarn to fabricate leather-like yarns. The leather-like yarns prepared in this study had good hygroscopic properties, mechanical properties (51.71 % strain and 4.49 cN/tex), and environmental stability (no more change withstood 24 h of bending, 50 cycles of immersion in 75 % ethanol solution, and 7 d of high and low temperature treatment). A no-salt and low-temperature dyeing method is further used to prepare color leather-like yarns, which requires less energy than polyester. These results provide guidance for the transition of recycling leather waste move to application, enabling the timely advancement of reusing leather waste initiatives in the textile industry.

Improving Corrosion-Resistant Properties of Heat-Resistant Structural Steel by a Low-Temperature Chemicothermal Treatment Based on Nitriding and Nicotriding Processes

Improving Corrosion-Resistant Properties of Heat-Resistant Structural Steel by a Low-Temperature Chemicothermal Treatment Based on Nitriding and Nicotriding Processes

Cloning and functional analysis of the BrCUC2 gene in Brassica rapa L.

The CUP-SHAPED COTYLEDON2 (CUC2) gene plays an important role in the formation of apical meristem and organ edges in plants. The apical meristematic tissue of Brassica rapa (B. rapa) is associated with cold resistance, however, the role of the CUC2 gene in cold resistance of B.rapa is unclear. In this study, we used bioinformatics software to analyze the structure of BrCUC2 gene, real-time fluorescence quantitative PCR to detect the expression level of BrCUC2, constructed transgenic Arabidopsis thaliana by the flower dipping method and subcellular localization for functional validation. The results showed that, we isolated a 1104 bp open reading frame of BrCUC2 from the winter B. rapa cultivar 'Longyou 7'. The BrCUC2 contains a highly conserved domain belonging to the NAM superfamily. Its homologus CUC genes contain similar conserved motifs and are closely related to Brassica oleracea (B.oleracea), and the N-terminal of amino acid sequence contains NAC domain. BrCUC2 protein was localized in the nucleus and self-activation tests showed that pGBKT7-BrCUC2 had self-activation. Tissue-specific expression analysis and promoter β-Glucuronidase (GUS) activity showed that BrCUC2 had high expression levels in B. rapa growth points and A. thaliana leaf edges, stems and growth points. After low-temperature stress, BrCUC2 showed greater expression in 'Longyou 7,' which presents strong cold resistance and concave growth points, than in 'Longyou 99,' which presents weak cold resistance and protruding growth points. BrCUC2 promoter contains multiple elements related to stress responses. BrCUC2 overexpression revealed that the phenotype did not differ from that of the wild type during the seedling stage but showed weak growth and a dwarf phenotype during the flowering and mature stages. After low-temperature treatment, the physiological indexes and survival rate of BrCUC2-overexpression lines of Arabidopsis thaliana (A. thaliana) were better than those of the wild type within 12h, although differences were not observed after 24h. These results showed that BrCUC2 improved the low-temperature tolerance of transgenic A. thaliana within a short time. It can provide a foundation for the study of cold resistance in winter B. rapa.

Characterization of NF–Y gene family and their expression and interaction analysis in Phalaenopsis orchid

The complex of Nuclear Factor Ys (NF-Ys), a family of heterotrimeric transcription factors composed of three unique subunits (NF-YA, NF-YB, and NF-YC), binds to the CCAAT box of eukaryotic promoters to activate or repress transcription of the downstream genes involved into various biological processes in plants. However, the systematic characterization of NF–Y gene family has not been elucidated in Phalaenopsis. A total of 24 NF–Y subunits (4 NF-YA, 9 NF-YB, and 11 NF-YC subunits) were identified in Phalaenopsis genome, whose exon/intron structures were highly differentiated among the PhNF-Y subunits. The distribution of motifs between coding regions of PhNF-YA and PhNF-YB/C was distinct. Segmental and tandem duplication events among paralogous PhNF-Ys were occurred. Six pairs of orthologous NF-Ys from Phalaenopsis and Arabidopsis and five pairs of orthologous NF-Ys from Phalaenopsis and rice involved in the phylogenetic gene synteny were identified. The various cis-elements being responsive to low-temperature, drought and ABA were distributed in the promoters of PhNF-Ys. qRT-PCR analysis indicated all of PhNF-Ys displayed the spatial specificity of expression in different tissues. Moreover, the expression levels of multiple PhNF-Ys significantly changed responding to low-temperature and ABA treatment. Yeast two hybrid and bimolecular fluorescence complementation assays approved the interaction of PhNF-YA1/3 with PhNF-YB6/PhNF-YC7, respectively, as well as PhNF-YB6 with PhNF-YC7. PhNF-YA1/3, PhNF-YB6, and PhNF-YC7 proteins were all localized in the nucleus. Further, transient overexpression of PhNF-YB6 and PhNF-YC7 promoted PhFT3 and repressed PhSVP expression in Phalaenopsis. These findings will facilitate to explore the role of PhNF-Ys in floral transition in Phalaenopsis orchid.