Genome-wide identification and evolutionary analysis of the NRAMP gene family in the AC genomes of Brassica species.

BACKGROUND: Brassica napus, a hybrid resulting from the crossing of Brassica rapa and Brassica oleracea, is one of the most important oil crops. Despite its significance, B. napus productivity faces substantial challenges due to heavy metal stress, especially in response to cadmium (Cd), which poses a significant threat among heavy metals. Natural resistance-associated macrophage proteins (NRAMPs) play pivotal roles in Cd uptake and transport within plants. However, our understanding of the role of BnNRAMPs in B. napus is limited. Thus, this study aimed to conduct genome-wide identification and bioinformatics analysis of three Brassica species: B. napus, B. rapa, and B. oleracea. RESULTS: A total of 37 NRAMPs were identified across the three Brassica species and classified into two distinct subfamilies based on evolutionary relationships. Conservative motif analysis revealed that motif 6 and motif 8 might significantly contribute to the differentiation between subfamily I and subfamily II within Brassica species. Evolutionary analyses and chromosome mapping revealed a reduction in the NRAMP gene family during B. napus evolutionary history, resulting in the loss of an orthologous gene derived from BoNRAMP3.2. Cis-acting element analysis suggested potential regulation of the NRAMP gene family by specific plant hormones, such as abscisic acid (ABA) and methyl jasmonate (MeJA). However, gene expression pattern analyses under hormonal or stress treatments indicated limited responsiveness of the NRAMP gene family to these treatments, warranting further experimental validation. Under Cd stress in B. napus, expression pattern analysis of the NRAMP gene family revealed a decrease in the expression levels of most BnNRAMP genes with increasing Cd concentrations. Notably, BnNRAMP5.1/5.2 exhibited a unique response pattern, being stimulated at low Cd concentrations and inhibited at high Cd concentrations, suggesting potential response mechanisms distinct from those of other NRAMP genes. CONCLUSIONS: In summary, this study indicates complex molecular dynamics within the NRAMP gene family under Cd stress, suggesting potential applications in enhancing plant resilience, particularly against Cd. The findings also offer valuable insights for further understanding the functionality and regulatory mechanisms of the NRAMP gene family.

Influence of Fracturing on a Coal Structure during Coalbed Methane Stimulation.

The impact of fracturing on coal seams includes not only mechanical alterations but also physical and chemical alterations. The coupling of these alterations plays an important role in the recovery of coalbed methane (CBM). 13C nuclear magnetic resonance (13C NMR), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and molecular models were conducted on coals with different degrees of fracturing to study the alterations in the coal structure during CBM stimulation. The 13C NMR results show that some aliphatic chains and oxygen-containing functional groups were shed, and some aliphatic rings were broken due to the effects of fracturing, which cause an increase in the relative content of aromatic carbon. The HRTEM and XRD results indicate that fracturing will result in a decrease in the interlayer spacing d002, an increase in the stacking height Lc, and a slight increase in the layer size La. Moreover, the orientation distribution in fractured coal was more intensive. The construction of molecular models also verified the variation of surface functional groups and interlayer spacing. Based on these analyses and molecular models, the alteration mechanism of functional groups and aromatic structures under fracturing was demonstrated. This study clarifies the alteration of the coal structure by fracturing and has important implications for the recovery of CBM.

A novel intelligent global harmony search algorithm based on improved search stability strategy.

Harmony search (HS) is a new swarm intelligent algorithm inspired by the process of music improvisation. Over the past decade, HS algorithm has been applied to many practical engineering problems. However, for some complex practical problems, there are some remaining issues such as premature convergence, low optimization accuracy and slow convergence speed. To address these issues, this paper proposes a novel intelligent global harmony search algorithm based on improved search stability strategy (NIGHS). In the search process, NIGHS uses the adaptive mean of harmony memory library to build a stable trust region around the global best harmony, and proposes a new coupling operation based on linear proportional relation, so that the algorithm can adaptively adjust the ability of exploration and exploitation in the search process and avoid premature convergence. In addition, the dynamic Gauss fine-tuning is adopted in the stable trust region to accelerate the convergence speed and improve the optimization accuracy. The common CEC2017 test functions are employed to test the proposed algorithm, the results show that NIGHS algorithm has a faster convergence speed and better optimization accuracy compared to the HS algorithm and its improved versions.

Research progress on the therapeutic effect and mechanism of metformin for lung cancer (Review).

Lung cancer is the most common type of cancer and the leading cause of cancer­associated death worldwide. Despite the availability of various treatments such as surgery, chemoradiotherapy, targeted drugs and immunotherapy, treatment is expensive and the prognosis remains poor. At present, lung cancer drugs and treatment programs remain in a state of continuous exploration and research to improve the prognosis, and to reduce the pain and economic burden for the patients. Type 2 diabetes is a common chronic disease in middle­aged and elderly patients, leading to significantly increased complications of cardiovascular and cerebrovascular diseases. Epidemiology shows that type 2 diabetes also increases the incidence of malignant tumors, including lung, liver, colorectal and pancreatic cancer. Metformin is a biguanide, widely used as a first­line oral drug in treating type 2 diabetes. Metformin has a hypoglycemic effect and a biological antitumor impact, reducing the incidence of various tumors, including lung cancer, and improving the prognosis of patients with tumors. The anti­lung cancer effect of metformin involves a variety of mechanisms that can improve the therapeutic effect and prognosis of lung cancer, as a single drug or in combination with other therapies. The present study aims to review the associated literature and the therapeutic effects of metformin on lung cancer.

First report of seedling blight caused by Fusarium tricinctum on Cynanchum stauntonii in China.

Cynanchum stauntonii is a perennial herb plant of the Asclepiadaceae family. The dried roots and rhizomes have been used as medicine in China for 1500 years and are considered a remedy for cough and phlegm. In recent years, the wild C. stauntonii resources have not been sufficient for market demand, therefore, a large artificial cultivation area was established in Xinzhou, Tuanfeng and Macheng in Hubei province. In March and April 2022, serious outbreaks of seedling blight were observed in C. stauntonii in Xinzhou county (N30°48'12″, E114°49'24″), and the disease occurred on 10 to 15% of plants in five C. stauntonii nursery beds. Early symptoms included withered tips, chlorosis, stunting, yellow leaves and leaf drop, and later, seedlings die in patches. To determine the causal agent of disease, pieces (5 mm × 5 mm) of diseased tissue at the junction of disease and healthy tissue were surface disinfected by soaking in 75% ethanol for 3 min, rinsed three times with sterilized water, and pieces were placed on PDA at 25°C. Fungal isolates obtained were yellow-brown at the center and pink to white toward the periphery, and dark red pigments were observed in the agar. Isolates were cultured in synthetic low nutrient agar (SNA) and carnation leaf agar to observe the spore morphology. The macroconidia were sickle-shaped with 3-4 septate, with sizes of 30.26±2.36×3.77±0.53 µm on SNA and 33.52±2.20×3.81±0.48 µm on carnation leaf agar (n=30). Morphological characteristics of the isolates were consistent with those of Fusarium sp in the Fusarium Laboratory Manual (Leslie et al. 2006). Furthermore, the genomic DNA from a representative isolate BQ-2 was extracted, the ITS, TEF-1α, RPB1 and RPB2 genes were amplified with primers ITS1/ITS4, EF1/EF2, Fa/G2R and 5F2/7cr, respectively (Zhang et al. 2022). BLAST analysis showed that the ITS (ON935780.1), TEF-1α (OP985126.1), RPB1 (OP985125.1) and RPB2 (OP985124.1) amplicon sequence were 99.44%, 98.94%, 99.88% and 100% identical to the sequences of F. tricinctum strain (KU350724.1, AB674264.1, LC701712.1, MW474678.1), respectively. A phylogenetic tree constructed based on a concatenated sequence (ITS, TEF-1α, RPB1, RPB2) using the neighbor-joining and maximum likelihood method in MEGA7 revealed that BQ-2 grouped with concatenated sequences from four representative F. tricinctum isolates in GenBank. Based on the morphological characteristics and molecular identification, the strain BQ-2 was identified as F. tricinctum. For pathogenicity tests, 5 mm pieces of a BQ-2 colony on PDA were placed on excised leaves of healthy C. stauntonii wounded with a needle (n=5) and kept at 25±2℃. Leaves treated PDA were used as a control (Li et al.2020). After three days inoculation, the mycelia proliferated and began to infect leaf tissues. Ten days later, large parts of the detached leaves were extensively infested with the pathogen and brown. For live plant inoculation, stem bases of five healthy seedlings were punctured with sterile needle and then inoculated with BQ-2 mycelia from PDA. Controls were treated with only PDA. The seedlings began wilting after three days and at five days showed typical disease symptoms, similar to those observed in the field. The controls were asymptomatic. The pathogen was reisolated from the diseased tissues, and the colonies and microscopic characteristics were similar to those of BQ-2. To the best of our knowledge, this is the first report of F. tricinctum causing seedling blight on C. stauntonii in China. This report will provide resources and reference for controlling the increased incidence and economic losses of seedling blight on C. stauntonii.

The Transitional Wettability on Bamboo-Leaf-like Hierarchical-Structured Si Surface Fabricated by Microgrinding.

Stabilizing the hydrophobic wetting state on a surface is essential in heat transfer and microfluidics. However, most hydrophobic surfaces of Si are primarily achieved through microtexturing with subsequent coating or modification of low surface energy materials. The coatings make the hydrophobic surface unstable and impractical in many industrial applications. In this work, the Si chips' wettability transitions are yielded from the original hydrophilic state to a stable transitional hydrophobic state by texturing bamboo-leaf-like hierarchical structures (BLHSs) through a diamond grinding wheel with one-step forming. Experiments showed that the contact angles (CAs) on the BLHS surfaces increased to 97° and only reduced by 2% after droplet impacts. This is unmatched by the current texturing surface without modification. Moreover, the droplets can be split up and transferred by the BLHS surfaces with their 100% mass. When the BLHS surfaces are modified by the low surface energy materials' coating, the hydrophobic BLHS surfaces are upgraded to be superhydrophobic (CA > 135°). More interestingly, the droplet can be completely self-sucked into a hollow micro-tube within 0.1 s without applying external forces. A new wetting model for BLHS surfaces based on the fractal theory is determined by comparing simulated values with the measured static contact angle of the droplets. The successful preparation of the bamboo-leaf-like Si confirmed that transitional wettability surfaces could be achieved by the micromachining of grinding on the hard and brittle materials. Additionally, this may expand the application potential of the key semiconductor material of Si.

Cold-inducible RNA-binding protein migrates from the nucleus to the cytoplasm under cold stress in normal human bronchial epithelial cells via TRPM8-mediated mechanism.

BACKGROUND: Cold-inducible RNA-binding protein (CIRP or hnRNP A18) is a multifunctional stress-responsive protein. Our previous study demonstrated that cold stress increased CIRP expression and migrated from the nucleus to the cytoplasm in airway epithelial cells. However, the mechanism through which CIRP migrates from the nucleus to the cytoplasm upon cold stress remains unknown. METHODS: The expression of CIRP in the bronchial epithelium was examined using immunofluorescence, real-time polymerase chain reaction (RT-PCR), and Western blotting. The expression of inflammatory factors interleukin-1ß (IL-1ß), interleukin-6 (IL-6), interleukin-8 (IL-8), and tumor necrosis factor-α (TNF-α) were detected by ELISA and RT-PCR. Transient receptor potential melastatin 8 (TRPM8) receptor function was characterized by Ca2+ imaging. RESULTS: Cold stress upregulated the expression of CIRP, inflammatory factors and promoted the translocation of CIRP from the nucleus to the cytoplasm in normal human bronchial epithelial (NHBE) cells. Cold stress activated the TRPM8/(Ca2+)/PKCα/glycogen synthase kinase 3ß (GSK3ß) signaling cascade, and that inhibition of this signaling pathway attenuated the migration of CIRP from the nucleus to cytoplasm but did not decrease its overexpression induced by cold stress. Knocked down CIRP expression or blocked CIRP migration between the nucleus and cytoplasm significantly decreased inflammatory factor expression. CONCLUSIONS: These results indicate that cold stress leads to the migration of CIRP from the nucleus to the cytoplasm with alteration of expression, which are involved in the expression of inflammatory factors (IL-1ß, IL-6, IL-8 and TNF-α) induced by cold air, through TRPM8/Ca2+/PKCα/GSK3ß signaling cascade.

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The nitrogen-doped carbon nanoparticles (N-CNPs) has a high potential of increasing nitrogen efficiency in farmland. However, little has been known about the effects of N-CNPs on soil microbial communities. In this study, paddy rhizosphere samples were collected from soils being treated with different nitrogen-doped amount of carbon nanoparticles (low, 1.2%, N-CNPs1; medium, 6.7%, N-CNPs2; high, 9.3%, N-CNPs3) for three years. We analyzed the bacterial community structure and diversity using the high-throughput sequencing. PICRUSt gene prediction analysis was used to determine soil community composition and metabolic function. Our results showed that treatment with N-CNPs changed the structure and diversity of soil microbial communities. Soil bacterial community diversity in adding medium amount of nitrogen-doped nanoparticles group (N-CNPs2) was the highest among all the treatments. Crenarchaeota, Acidobacteria and Planctomycetes were the most dominant groups in the soil microbial community. The relative abundances of Crenarchaeota, Acidobacteria and Verrucomicrobia increased, whereas Planctomycetes, Chloroflexi and Nitrospirae decreased with adding N-CNPs. Results of PICRUSt analysis revealed a wide genetic diversity of organisms involved in adding N-CNPs, such as amino acid metabolism, carbohydrate metabolism, lipid metabolism and environmental information processes. Heat map analysis of KEGG demonstrated that adding medium amount of nitrogen-doped nanoparticles (N-CNPs2) group increased the relative abundance of bacterial community associated with soil carbon and nitrogen metabolism.

Finite Element Simulation of the Machining Process of Boiling Structures in a Novel Radial Heat Sink for High-Power LEDs.

A phase change heat sink has higher heat transfer efficiency compared to a traditional metal solid heat sink, and is thus more preferred for the heat dissipation of high-power light-emitting diodes (LEDs) with very high heat flux. The boiling structure at the evaporation surface is the biggest factor that affects heat sink resistance. It is necessary to investigate the plastic deformation law during the machining process of boiling structures. In this study, a novel phase change radial heat sink was developed for high-power LED heat dissipation. First, a working principle and a fabrication process for the heat sink were introduced. Subsequently, to achieve an excellent heat dissipation performance, the machining process of boiling structures was numerically simulated and investigated. To be specific, plastic deformation generated during the formation was analyzed, and key parameters related to the morphology of the boiling structures were discussed including feeding angles and machining depths. Moreover, the finite element (FE) simulation results were compared with those of experiments. Last but not least, the heat transfer performance of the fabricated heat sink was tested. Results showed that the developed heat sink was well suited for a high-power LED application.

Characterization of an Asymptomatic Cohort of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infected Individuals Outside of Wuhan, China.

PURPOSE: We aimed to further clarify the epidemiological and clinical characteristics of asymptomatic severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. METHODS: We identified close contacts of confirmed coronavirus disease 2019 (COVID-19) cases in northeast Chongqing, China, who were confirmed by real-time reverse transcription polymerase chain reaction-positive (RT-PCR+). We stratified this cohort by normal vs abnormal findings on chest computed tomography (CT) and compared the strata regarding comorbidities, demographics, laboratory findings, viral transmission and other factors. RESULTS: Between January 2020 and March 2020, we identified and hospitalized 279 RT-PCR+ contacts of COVID-19 patients. 63 (23%) remained asymptomatic until discharge; 29 had abnormal and 34 had normal chest CT findings. The mean cohort age was 39.3 years, and 87.3% had no comorbidities. Mean time to diagnosis after close contact with a COVID-19 index patient was 16.0 days, and it was 13.4 days and 18.7 days for those with abnormal and normal CT findings, respectively (P < .05). Nine patients (14.3%) transmitted the virus to others; 4 and 5 were in the abnormal and normal CT strata, respectively. The median length of time for nucleic acid to turn negative was 13 days compared with 10.4 days in those with normal chest CT scans (P < .05). CONCLUSIONS: A portion of asymptomatic individuals were capable of transmitting the virus to others. Given the frequency and potential infectiousness of asymptomatic infections, testing of traced contacts is essential. Studies of the impact of treatment of asymptomatic RT-PCR+ individuals on disease progression and transmission should be undertaken.

Monitoring methylation-driven genes as prognostic biomarkers in patients with lung squamous cell cancer.

Aberrant DNA methylations have been reported to be significantly associated with lung squamous cell cancer (LUSC). The aim of this study was to investigate the DNA methylation-driven genes in LUSC by integrative bioinformatics analysis. In the present study, methylation-driven genes in LUSC were screened out, and survival analysis related to these genes was performed to confirm their value in prognostic assessment. Gene expression and methylation data were downloaded from The Cancer Genome Atlas (TCGA), and the MethylMix algorithm was used to identify methylation-driven genes. ConsensusPathDB was used to perform Gene Ontology and pathway enrichment analysis of methylation-driven genes. Survival analysis was performed to investigate the correlation with prognosis. In total, 52 differentially expressed methylation-driven genes were identified in LUSC and adjacent tissues. Survival analysis showed that DQX1, GPR75, STX12, and TRIM61 could serve as independent prognostic biomarkers. In addition, the combined methylation and gene expression survival analysis revealed that the combined expression level of the genes ALG1L, DQX1, and ZNF418 alone can be used as a prognostic marker or drug target. Methylation of four sites of gene ZNF418, four sites of ZNF701, two sites of DQX1, and four sites of DCAF4L2 was significantly associated with survival. The present study provides an important bioinformatic and relevant theoretical basis for subsequent early diagnosis and prognostic assessment of LUSC.

Numerical Simulation, Machining and Testing of a Phase Change Heat Sink for High Power LEDs.

Thermal management is crucial to guarantee the normal operation of light-emitting diodes (LEDs) Phase change heat sink is superior to traditional metal solid heat sink due to very small thermal resistance. In this study, a new type of phase change heat sink for high power LEDs is first designed. Then, the fabrication process of boiling structures at the evaporation surface of the phase change heat sink is discussed and analyzed. To make a comparison and deep discussion, the machining process is simulated through the FEM (finite element analysis) software, DEFORM-3D. Last but not least, heat transfer performance of the fabricated phase change heat sink is tested. Results have shown that the designed new type of phase change heat sink has superior heat transfer performance and is suitable for heat dissipation of high-power LEDs.

Overexpressing heat-shock protein OsHSP50.2 improves drought tolerance in rice.

KEY MESSAGE: OsHSP50.2, an HSP90 family gene up-regulated by heat and osmotic stress treatments, positively regulates drought stress tolerance probably by modulating ROS homeostasis and osmotic adjustment in rice. Heat-shock proteins (HSPs) serve as molecular chaperones for a variety of client proteins in abiotic stress response and play pivotal roles in protecting plants against stress, but the molecular mechanism remains largely unknown. Here, we report an HSP90 family gene, OsHSP50.2, which acts as a positive regulator in drought stress tolerance in rice (Oryza sativa). OsHSP50.2 was ubiquitously expressed and its transcript level was up-regulated by heat and osmotic stress treatments. Overexpression of OsHSP50.2 in rice reduced water loss and enhanced the transgenic plant tolerance to drought and osmotic stresses. The OsHSP50.2-overexpressing plants exhibited significantly lower levels of electrolyte leakage and malondialdehyde (MDA) and less decrease of chlorophyll than wild-type plants under drought stress. Moreover, the OsHSP50.2-overexpressing plants had significantly higher SOD activity under drought stress compared with the wild type. These results imply that OsHSP50.2 positively regulates drought stress tolerance in rice, probably through the modulation of reactive oxygen species (ROS) homeostasis. Additionally, the OsHSP50.2-overexpressing plants accumulated significantly higher content of proline than the wild type under drought stress, which contributes to the improved protection ability from drought stress damage via osmotic adjustment. Our findings reveal that OsHSP50.2 plays a crucial role in drought stress response, and it may possess high potential usefulness in drought tolerance improvement of rice.

The Arabidopsis AtUNC-93 Acts as a Positive Regulator of Abiotic Stress Tolerance and Plant Growth via Modulation of ABA Signaling and K+ Homeostasis.

Potassium (K+) is one of the essential macronutrients required for plant growth and development, and the maintenance of cellular K+ homeostasis is important for plants to adapt to abiotic stresses and growth. However, the mechanism involved has not been understood clearly. In this study, we demonstrated that AtUNC-93 plays a crucial role in this process under the control of abscisic acid (ABA). AtUNC-93 was localized to the plasma membrane and mainly expressed in the vascular tissues in Arabidopsis thaliana. The atunc-93 mutants showed typical K+-deficient symptoms under low-K+ conditions. The K+ contents of atunc-93 mutants were significantly reduced in shoots but not in roots under either low-K+ or normal conditions compared with wild type plants, whereas the AtUNC-93-overexpressing lines still maintained relatively higher K+ contents in shoots under low-K+ conditions, suggesting that AtUNC-93 positively regulates K+ translocation from roots to shoots. The atunc-93 plants exhibited dwarf phenotypes due to reduced cell expansion, while AtUNC-93-overexpressing plants had larger bodies because of increased cell expansion. After abiotic stress and ABA treatments, the atunc-93 mutants was more sensitive to salt, drought, osmotic, heat stress and ABA than wild type plants, while the AtUNC-93-overexpressing lines showed enhanced tolerance to these stresses and insensitive phenotype to ABA. Furthermore, alterations in the AtUNC-93 expression changed expression of many ABA-responsive and stress-related genes. Our findings reveal that AtUNC-93 functions as a positive regulator of abiotic stress tolerance and plant growth by maintaining K+ homeostasis through ABA signaling pathway in Arabidopsis.

Rice WRKY4 acts as a transcriptional activator mediating defense responses toward Rhizoctonia solani, the causing agent of rice sheath blight.

WRKY transcription factors have been implicated in the regulation of transcriptional reprogramming associated with various plant processes but most notably with plant defense responses to pathogens. Here we demonstrate that expression of rice WRKY4 gene (OsWRKY4) was rapidly and strongly induced upon infection of Rhizoctonia solani, the causing agent of rice sheath blight, and exogenous jasmonic acid (JA) and ethylene (ET). OsWRKY4 is localized to the nucleus of plant cells and possesses transcriptional activation ability. Modulation of OsWRKY4 transcript levels by constitutive overexpression increases resistance to the necrotrophic sheath blight fungus, concomitant with elevated expression of JA- and ET-responsive pathogenesis-related (PR) genes such as PR1a, PR1b, PR5 and PR10/PBZ1. Suppression by RNA interference (RNAi), on the other hand, compromises resistance to the fungal pathogen. Yeast one-hybrid assay and transient expression in tobacco cells reveal that OsWRKY4 specifically binds to the promoter regions of PR1b and PR5 which contain W-box (TTGAC[C/T]), or W-box like (TGAC[C/T]) cis-elements. In conclusion, we propose that OsWRKY4 functions as an important positive regulator that is implicated in the defense responses to rice sheath blight via JA/ET-dependent signal pathway.

OsGL1-3 is involved in cuticular wax biosynthesis and tolerance to water deficit in rice.

Cuticular wax covers aerial organs of plants and functions as the outermost barrier against non-stomatal water loss. We reported here the functional characterization of the Glossy1(GL1)-homologous gene OsGL1-3 in rice using overexpression and RNAi transgenic rice plants. OsGL1-3 gene was ubiquitously expressed at different level in rice plants except root and its expression was up-regulated under ABA and PEG treatments. The transient expression of OsGL1-3-GFP fusion protein indicated that OsGL1-3 is mainly localized in the plasma membrane. Compared to the wild type, overexpression rice plants exhibited stunted growth, more wax crystallization on leaf surface, and significantly increased total cuticular wax load due to the prominent changes of C30-C32 aldehydes and C30 primary alcohols. While the RNAi knockdown mutant of OsGL1-3 exhibited no significant difference in plant height, but less wax crystallization and decreased total cuticular wax accumulation on leaf surface. All these evidences, together with the effects of OsGL1-3 on the expression of some wax synthesis related genes, suggest that OsGL1-3 is involved in cuticular wax biosynthesis. Overexpression of OsGL1-3 decreased chlorophyll leaching and water loss rate whereas increased tolerance to water deficit at both seedling and late-tillering stages, suggesting an important role of OsGL1-3 in drought tolerance.

Cloning of TTG1 gene and PCR identification of genomes A, B and C in Brassica species.

Arabidopsis Transparent Testa Glabra 1 (TTG1) genes were cloned from three diploid Brassica species (B. rapa, B. nigra and B. oleracea) and two amphidiploids species (B. juncea and B. carinata) by homology cloning. TTG1 homologues identified in all the accessions of the investigated species had a coding sequence of 1,014 bp. One copy was obtained from each diploid species and two copies from each amphidiploid species. Combined analysis of the TTG1 sequences cloned in this study with those obtained from public databases demonstrated that three, forty-five and seven nucleotides were specific variations in TTG1 genes from genomes A, B and C, respectively. Primers designed with genome-specific nucleotide variations were able to distinguish among TTG1 genes originating from genomes A, B and C in Brassica. Therefore, the TTG1 gene could serve as a candidate marker gene to detect the pollen flow of Brassica and provide an alternative method for the detection of pollen drift and risk assessment of gene flow in Brassica species.

Transcriptome profile reveals heat response mechanism at molecular and metabolic levels in rice flag leaf.

Flag leaf is one of the key photosynthesis organs during rice reproductive stage. A time course microarray analysis of rice flag leaf was done after 40°C treatment for 0 min, 20 min, 60 min, 2h, 4h, and 8h. The identified significant heat responsive genes were mainly involved in transcriptional regulation, transport, protein binding, antioxidant, and stress response. KMC analysis discovered the time-dependent gene expression pattern under heat. MapMan analysis demonstrated that, under heat treatment, Hsp genes and genes involved in glycolysis and ubiquitin-proteasome were enhanced, and genes involved in TCA, carotenoid, dihydroflavonol and anthocyanin metabolisms and light-reaction in the photosynthesis were widely repressed. Meanwhile, some rate-limiting enzyme genes in shikimate, lignin, and mevalonic acid metabolisms were up-regulated, revealing the importance of maintaining specific secondary metabolites under heat stress. The present study increased our understanding of heat response in rice flag leaf and provided good candidate genes for crop improvement.

Heat shock factor OsHsfB2b negatively regulates drought and salt tolerance in rice.

KEY MESSAGE: Expression of OsHsfB2b was strongly induced by heat, salt, ABA and PEG treatments. Drought and salt tolerances were significantly decreased by OsHsfB2b overexpression, but were enhanced by RNA interference. ABSTRACT: Plants have more than 20 heat shock factors (Hsfs) that were designated class A, B, and C. Many members of Class A Hsfs were characterized as activators of transcription, but the functional roles of class B and C Hsfs have not been fully recognized. OsHsfB2b is a member of class B Hsfs in rice (Oryza sativa). Expression of OsHsfB2b was strongly induced by heat, salt, abscisic acid (ABA) and polyethylene glycol (PEG) treatments but was almost not affected by cold stress. Drought and salt tolerances were significantly decreased in OsHsfB2b-overexpressing transgenic rice, but were enhanced in the OsHsfB2b-RNAi transgenic rice. Under drought stress, the OsHsfB2b-overexpressing transgenic rice exhibited increased relative electrical conductivity (REC) and content of malondialdehyde (MDA) and decreased proline content compared with the wild type, while the lower REC and MDA content and increased proline content were found in the OsHsfB2b-RNAi transgenic rice. These results suggest that OsHsfB2b functions as a negative regulator in response to drought and salt stresses in rice, with its existing B3 repression domain (BRD) that might be necessary for the repressive activity. The present study revealed the potential value of OsHsfB2b in genetic improvement of rice.