Constructing an efficient and easy-to-operate multigene expression system is currently a crucial part of plant genetic engineering. In this study, a fragment carrying three independent gene expression cassettes and the expression unit of the gene-silencing suppressor protein(RNA silencing suppressor 19 kDa protein, P19) simultaneously was designed and constructed. This fragment was cloned into the commonly used plant expression vector pCAMBIA300, and the plasmid pC1300-TP2-P19 was obtained. Each gene expression cassette consists of different promoters, fusion tags, and terminators. The target gene can be flexibly inserted into the corresponding site through enzymatic digestion and ligation or recombination and fused with different protein tags, which provides great convenience for subsequent detection. The enhanced green fluorescent protein(eGFP) reporter gene was individually constructed into each expression cassette to verify the feasibility of this vector system. The results of tobacco transient expression and laser-confocal microscopy showed that each expression cassette presented independent and normal expression. Meanwhile, the three key enzyme genes in the betanin synthesis pathway, BvCYP76AD, BvDODA1, and DbDOPA5GT, were constructed into the three expression cassettes. The results of tobacco transient expression phenotype, protein immunoblotting(Western blot), and chemical detection of product demonstrated that the three exogenous genes were highly expressed, and the target compound betanin was successfully produced. The above results indicated that the constructed multigene expression system for plants in this study was efficient and reliable and can achieve the co-transformation of multiple plant genes. It can provide a reliable vector platform for the analysis of plant natural product synthesis pathways, functional verification, and plant metabolic engineering.
Nicotiana/metabolism* ; Genetic Vectors/metabolism* ; Gene Expression Regulation, Plant ; Plant Proteins/metabolism* ; Plants, Genetically Modified/metabolism* ; Genetic Engineering/methods* ; Green Fluorescent Proteins/metabolism* ; Gene Expression

OBJECTIVES: To evaluate the protective effect of Bufei Yishen Formula (BYF) against cigarette smoke extract (CSE)-induced injuries in human bronchial epithelial BEAS-2B cells and explore the underlying mechanism. METHODS: BEAS-2B cells exposed to CSE were treated with normal rat serum, BYF-medicated rat serum at low or high doses, pyrrolidine dithiocarbamate (PDTC, a NF-κB inhibitor), PDTC combined with high-dose BYF-medicated serum, or S-carbomethyloysteine (S-CMC, as the positive control). CCK-8 assay was used to determine the optimal concentration and treatment time of CSE, BYF-medicated serum and S-CMC. The treated cells were examined for inflammatory factor levels in the supernatant and cellular expressions of MUC5AC and MUC5B using ELISA, cell ultrastructural changes with transmission electron microscopy, and cell apoptosis rate using flow cytometry. The expression levels of TLR4/NF‑κB pathway-associated mRNAs and proteins were determined by qRT-PCR and Western blotting. RESULTS: CSE exposure significantly increased secretions of IL-1β, IL-6 and TNF-α, mRNA and protein expressions of MUC5AC and MUC5B, and early and total apoptosis rates in BEAS-2B cells, where the presence of apoptotic bodies was detected. CSE also significantly enhanced the mRNA and protein expressions of TLR4, I-κB, and NF-κB and reduced mRNA and protein expressions of AQP5. Treatments of the CSE-exposed cells with BYF-medicated serum, PDTC and S-CMC all significantly lowered inflammatory factor levels, MUC5AC and MUC5B expressions, and early and total cell apoptosis rates, and partly reversed the changes in cellular ultrastructure and mRNA and protein expressions of the TLR4/NF-κB pathway, and the effects were the most conspicuous following the combined treatment with high-dose BYF-medicated serum and PDTC. CONCLUSIONS BYF can inhibit cell apoptosis, inflammation and mucus hypersecretion in CSE-induced BEAS-2B cells by inhibiting the TLR4/NF-κB signaling pathway.
Humans ; Epithelial Cells/cytology* ; Drugs, Chinese Herbal/pharmacology* ; NF-kappa B/metabolism* ; Bronchi/cytology* ; Smoke/adverse effects* ; Apoptosis/drug effects* ; Mucin 5AC/metabolism* ; Cell Line ; Toll-Like Receptor 4/metabolism* ; Mucin-5B/metabolism* ; Signal Transduction/drug effects* ; Nicotiana ; Rats ; Thiocarbamates/pharmacology* ; Animals

Microalgae possess high photosynthetic efficiency, robust adaptability, and substantial biomass, serving as excellent biological resources for large-scale cultivation. Malic enzyme (ME), a ubiquitous metabolic enzyme in living organisms, catalyzes the decarboxylation of malate to produce pyruvate, CO₂, and NAD(P)H, playing a role in multiple metabolic pathways including energy metabolism, photosynthesis, respiration, and biosynthesis. In this study, we identified the Scenedesmus quadricauda malic enzyme gene (SqME) and its biological functions, aiming to provide excellent target genes for the genetic improvement of higher plants. Based on the RNA-seq data from S. quadricauda under the biofilm cultivation mode with high CO₂ and light energy transfer efficiency and small water use, a highly expressed gene (SqME) functionally annotated as ME was cloned. The physicochemical properties of the SqME-encoded protein were systematically analyzed by bioinformatics tools. The subcellular localization of SqME was determined via transient transformation in Nicotiana benthamiana leaves. The biological functions of SqME were identified via genetic transformation in Nicotiana tabacum, and the potential of SqME in the genetic improvement of higher plants was evaluated. The ORF of SqME was 1 770 bp, encoding 590 amino acid residues, and the encoded protein was located in chloroplasts. SqME was a NADP-ME, with the typical structural characteristics of ME. The ME activity in the transgenic N. tabacum plant was 1.8 folds of that in the wild-type control. Heterologous expression of SqME increased the content of chlorophyll a, chlorophyll b, and total chlorophyll by 20.9%, 26.9%, and 25.2%, respectively, compared with the control. The transgenic tobacco leaves showed an increase of 54.0% in the fluorescence parameter NPQ and a decrease of 30.1% in Fo compared with the control. Moreover, the biomass, total lipids, and soluble sugars in the transgenic tobacco leaves enhanced by 20.5%, 25.7%, and 9.5%, respectively. On the contrary, the starch and protein content in the transgenic tobacco leaves decreased by 22.4% and 12.2%, respectively. Collectively, the SqME-encoded protein exhibited a strong enzymatic activity. Heterologous expressing of SqME could significantly enhance photosynthetic protection, photosynthesis, and biomass accumulation in the host. Additionally, SqME can facilitate carbon metabolism remodeling in the host, driving more carbon flux towards lipid synthesis. Therefore, SqME can be applied in the genetic improvement of higher plants for enhancing photosynthetic carbon fixation and lipid accumulation. These findings provide scientific references for mining of functional genes from S. quadricauda and application of these genes in the genetic engineering of higher plants.
Nicotiana/genetics* ; Photosynthesis/physiology* ; Malate Dehydrogenase/biosynthesis* ; Plant Leaves/genetics* ; Scenedesmus/enzymology* ; Carbon Cycle/genetics* ; Lipid Metabolism/genetics* ; Plants, Genetically Modified/metabolism*

Geminiviruses cause substantial crop yield losses worldwide. The replication initiator protein (Rep) encoded by geminiviruses is indispensable for geminiviral replication. The Rep protein encoded by beet severe curly top virus (BSCTV, genus Curtovirus, family Geminiviridae) induces VARIANT IN METHYLATION 5 (VIM5) expression in Arabidopsis leaves upon BSCTV infection. VIM5 functions as a ubiquitination-related E3 ligase to promote the proteasomal degradation of methyltransferases, resulting in reduction of methylation levels in the BSCTV C2-3 promoter. However, the specific domains of Rep responsible for VIM5 induction remain poorly characterized. Although Rep proteins from several geminiviruses act as viral suppressors of RNA silencing (VSRs), whether BSCTV Rep also possesses VSR activity remains to be illustrated. In this study, we employed a transient expression system in the 16c-GFP transgenic and the wild-type Nicotiana benthamiana plants to analyze the VSR and the VIM5-inducing activities of different truncated Rep proteins haboring distinct domains. We found that the N-terminal domain (amino acids 1-180) of Rep suppressed GFP silencing in 16c-GFP transgenic N. benthamiana leaves. The minimal N-terminal fragment (amino acids 1-104) induced VIM5 expression upon co-infiltration, while C-terminal truncations lacked VIM5-inducing activity. Our results indicate that the N-terminal domain of Rep encoded by BSCTV mediates the suppression of RNA silencing and induces VIM5 expression. Thus, our findings contribute to a better understanding of interactions between geminiviral Rep and plant hosts.
Geminiviridae/genetics* ; Nicotiana/metabolism* ; Arabidopsis/metabolism* ; RNA Interference ; Viral Proteins/metabolism* ; Arabidopsis Proteins/metabolism* ; Plants, Genetically Modified/metabolism* ; Protein Domains ; Plant Diseases/virology* ; Methyltransferases/metabolism* ; Ubiquitin-Protein Ligases/metabolism* ; DNA Helicases/genetics*

Pepino mosaic virus (PepMV) causes severe disease in tomato and other Solanaceous crops around globe. To effectively study and manage this viral disease, researchers need new, sensitive, and high-throughput approaches for viral detection. In this study, we purified PepMV particles from the infected Nicotiana benthamiana plants and used virions to immunize BALB/c mice to prepare hybridomas secreting anti-PepMV monoclonal antibodies (mAbs). A panel of highly specific and sensitive murine mAbs (15B2, 8H6, 23D11, 20D9, 3A6, and 8E3) could be produced through cell fusion, antibody selection, and cell cloning. Using the mAbs as the detection antibodies, we established double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA), Dot-ELISA, and Tissue print-ELISA for detecting PepMV infection in tomato plants. Resulting data on sensitivity analysis assays showed that both DAS-ELISA and Dot-ELISA can efficiently monitor the virus in PepMV-infected tissue crude extracts when diluted at 1:1 310 720 and 1:20 480 (weight/volume ratio (w/v), g/mL), respectively. Among the three methods developed, the Tissue print-ELISA was found to be the most practical detection technique. Survey results from field samples by the established serological approaches were verified by reverse transcription polymerase chain reaction (RT-PCR) and DNA sequencing, demonstrating all three serological methods are reliable and effective for monitoring PepMV. Anti-PepMV mAbs and the newly developed DAS-ELISA, Dot-ELISA, and Tissue print-ELISA can benefit PepMV detection and field epidemiological study, and management of this viral disease, which is already widespread in tomato plants in Yunnan Province of China.
Animals ; Antibodies, Monoclonal/immunology* ; China ; Cloning, Molecular ; Enzyme-Linked Immunosorbent Assay/methods* ; Female ; Hybridomas ; Solanum lycopersicum/virology* ; Mice ; Mice, Inbred BALB C ; Plant Diseases/virology* ; Potexvirus/metabolism* ; Sensitivity and Specificity ; Nicotiana

Production of reactive oxygen species (ROS) is a conserved immune response primarily mediated by NADPH oxidases (NOXs), also known in plants as respiratory burst oxidase homologs (RBOHs). Most microbe-associated molecular patterns (MAMPs) trigger a very fast and transient ROS burst in plants. However, recently, we found that lipopolysaccharides (LPS), a typical bacterial MAMP, triggered a biphasic ROS burst. In this study, we isolated mutants defective in LPS-triggered biphasic ROS burst (delt) in Arabidopsis, and cloned the DELT1 gene that was shown to encode RBOHD. In the delt1-2 allele, the antepenultimate residue, glutamic acid (E919), at the C-terminus of RBOHD was mutated to lysine (K). E919 is a highly conserved residue in NADPH oxidases, and a mutation of the corresponding residue E568 in human NOX2 has been reported to be one of the causes of chronic granulomatous disease. Consistently, we found that residue E919 was indispensable for RBOHD function in the MAMP-induced ROS burst and stomatal closure. It has been suggested that the mutation of this residue in other NADPH oxidases impairs the protein's stability and complex assembly. However, we found that the E919K mutation did not affect RBOHD protein abundance or the ability of protein association, suggesting that the residue E919 in RBOHD might have a regulatory mechanism different from that of other NOXs. Taken together, our results confirm that the antepenultimate residue E is critical for NADPH oxidases and provide a new insight into the regulatory mechanisms of RBOHD.
Agrobacterium tumefaciens/metabolism* ; Alleles ; Arabidopsis/metabolism* ; Arabidopsis Proteins/genetics* ; Gene Expression Regulation, Plant ; Genetic Techniques ; Humans ; Lipopolysaccharides/metabolism* ; Luminescence ; Mutation ; NADPH Oxidase 2/chemistry* ; NADPH Oxidases/genetics* ; Plant Stomata/metabolism* ; Protein Domains ; Reactive Oxygen Species/metabolism* ; Nicotiana/metabolism*