In this study, Saccharomyces cerevisiae R0 was used as the chassis cell to synthesize oleanolic acid from scratch through the heterologous expression of β-amyrin synthase(β-AS) from Glycyrrhiza uralensis, cytochrome P450 enzyme CYP716A154 from Catharanthus roseus, and cytochrome P450 reductase AtCPR from Arabidopsis thaliana. The engineered strain R1 achieved shake flask titres of 5.19 mg·L~(-1). By overexpressing enzymes in the pentose phosphate pathway(PPP)(ZWF1, GND1, TKL1, and TAL), the NADH kinase gene in the mitochondrial matrix(POS5), truncated 3-hydroxy-3-methylglutaryl-CoA reductase(tPgHMGR1) from Panax ginseng, and farnesyl diphosphate synthase gene(SmFPS) from Salvia miltiorrhiza, the precursor supply and intracellular reduced nicotinamide adenine dinucleotide phosphate(NADPH) supply were enhanced, resulting in an 11.4-fold increase in squalene yield and a 3.6-fold increase in oleanolic acid yield. Subsequently, increasing the copy number of the heterologous genes tPgHMGR1, β-AS, CYP716A154, and AtCPR promoted the metabolic flow towards the final product, oleanolic acid, and increased the yield by three times. Shake flask fermentation data showed that, by increasing the copy number, precursor supply, and intracellular NADPH supply, the final engineered strain R3 could achieve an oleanolic acid yield of 53.96 mg·L~(-1), which was 10 times higher than that of the control strain R1. This study not only laid the foundation for the green biosynthesis of oleanolic acid but also provided a reference for metabolic engineering research on other pentacyclic triterpenoids in S. cerevisiae.
Oleanolic Acid/biosynthesis* ; Saccharomyces cerevisiae/metabolism* ; Industrial Microbiology ; Microorganisms, Genetically-Modified/metabolism* ; Plants/enzymology* ; Fermentation ; Metabolic Engineering

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

Sweet-tasting proteins demonstrate application potential in foods and beverages due to their high sweetness, low calorie, and non-toxicity. So far, eight natural sweet-tasting proteins have been obtained from natural plants. This paper briefs the sweetness properties of the eight proteins and the molecular mechanism of the sweetness, reviews the progress in the genetic engineering, heterologous expression, and molecular modification of three representative sweet-tasting proteins (monellin, brazzein, and thaumatin), and summarizes their expression yields in different hosts and sweetness properties. Lastly, this paper prospects the research, application, and industrial development of sweet-tasting proteins. This review provides a reference for further research and development of new proteinaceous sweeteners.
Plant Proteins/biosynthesis* ; Genetic Engineering/methods* ; Sweetening Agents/chemistry* ; Plants, Genetically Modified/metabolism*

The protein kinase A/protein kinase G/protein kinase C-family (AGC kinase family) of eukaryotes is involved in regulating numerous biological processes. The 3-phosphoinositide- dependent protein kinase 1 (PDK1), is a conserved serine/threonine kinase in eukaryotes. To understand the roles of PDK1 homologous genes in cell death and immunity in tetraploid Nicotiana tabacum, the previuosly generated transgenic CRISPR/Cas9 lines, in which 5-7 alleles of the 4 homologous PDK1 genes (NtPDK1a/1b/1c/1d homologs) simultaneously knocked out, were used in this study. Our results showed that the hypersensitive response (HR) triggered by transient overexpression of active Pto (Pto^Y207D) or soybean GmMEKK1 was significantly delayed, whereas the resistance to Pseudomonas syrangae pv. tomato DC3000 (Pst DC3000) and tobacco mosaic virus (TMV) was significantly elevated in these partial knockout lines. The elevated resistance to Pst DC3000 and TMV was correlated with the elevated activation of NtMPK6, NtMPK3, and NtMPK4. Taken together, our results indicated that NtPDK1s play a positive role in cell death but a positive role in disease resistance, likely through negative regulation of the MAPK signaling cascade.
Nicotiana/virology* ; Disease Resistance/genetics* ; Plant Diseases/immunology* ; Plants, Genetically Modified/genetics* ; Gene Knockout Techniques ; Plant Proteins/genetics* ; CRISPR-Cas Systems ; Protein Serine-Threonine Kinases/genetics* ; 3-Phosphoinositide-Dependent Protein Kinases/genetics* ; Pyruvate Dehydrogenase Acetyl-Transferring Kinase ; Tobacco Mosaic Virus/pathogenicity*

The OsSPL10 gene has previously been reported to positively regulate trichome development and negatively regulate salt and drought stress tolerance in rice. However, it is not clear whether this gene can be used for gene editing to create new germplasm of glabrous leaf and salt-tolerant rice. In this study, we created six rice mutants by CRISPR/Cas9-mediated editing of OsSPL10 from 'Xinfeng 2', 'Xinkedao 31', and 'Xindao 25', the main rice cultivars along the Yellow River. Visual observation and scanning electron microscopy verified that the mutants lacked trichomes on the leaves and glumes, and the expression of glabrous marker genes OsHL6, OsGL6, and OsWOX3B in mutants was down-regulated compared with that in the wild type. The net photosynthetic rate, stomatal conductance, and transpiration rate of flag leaves in the mutants were significantly higher than those in the wild type. In addition, the survival rates of the mutants were much higher than that of the wild type after 7 days of treatment with 200 mmol/L NaCl. The results of quantitative real-time polymerase chain reaction (qRT-PCR) further verified that compared with the wild type, the mutants demonstrated down-regulated expression of the salt stress-related gene OsGASR1 and up-regulated expression of OsNHX2 and OsIDS1. Statistical analysis of agronomic traits showed that the mutants had increased plant height and no significant changes in yield-related traits compared with the wild type. The six spl10 mutants created in this study not only had glabrous leaves and glumes but also demonstrated enhanced tolerance to salt stress, serving as new germplasm resources for directional breeding of rice along the Yellow River.
Oryza/physiology* ; CRISPR-Cas Systems/genetics* ; Salt Tolerance/genetics* ; Gene Editing/methods* ; Plant Proteins/genetics* ; Rivers ; Plant Leaves/genetics* ; Mutation ; Plants, Genetically Modified/genetics* ; China

Laccases (LACs), belonging to the multicopper oxidase family, are closely associated with various biological functions including lignin synthesis and responses to biotic and abiotic stresses in plants. However, few studies have reported the laccase genes in China rose (Rosa chinensis). Prickles cause difficulties to the management and harvest of R. chinensis and have become a trait concerned in the breeding. To investigate the expression patterns of laccase genes in roses, we cloned a laccase gene from an ancient variety R. chinensis 'Old Blush' and named it RcLAC15. The expression level of RcLAC15 in prickles was significantly higher than those in roots, stems, and leaves. Fifty-eight laccase genes were identified in the genome of R. chinensis, and bioinformatics analysis revealed that RcLAC15 was a homolog of AtLAC15, predicting that RcLAC15 was a stable hydrophilic protein without transmembrane structures. The recombinant expression vector pBI121-proRcLAC15:: GUS was introduced into Arabidopsis, and GUS staining results showed that the RcLAC15 promoter specifically drove GUS gene expression at the edges of Arabidopsis leaves. In summary, RcLAC15 is a gene specifically expressed in the prickles of R. chinensis. This discovery provides a reference for exploring the biological functions of laccase genes in the prickles of R. chinensis.
Laccase/metabolism* ; Rosa/enzymology* ; Cloning, Molecular ; Gene Expression Regulation, Plant ; Plant Proteins/metabolism* ; Arabidopsis/metabolism* ; Plants, Genetically Modified/metabolism*

Cucumber (Cucumis sativus L.) is one of the most widely cultivated vegetables in the world. High temperature and other stress conditions can affect the growth and development of this plant, even leading to the decreases in yield and quality. The mitogen-activated protein kinase (MAPK) family plays a crucial role in plant stress responses. However, the role of MPK4 in the stress response of cucumber remains to be reported. In this study, we cloned CsMPK4, which encoded 383 amino acid residues. The qRT-PCR results showed that the expression level of CsMPK4 was the highest in leaves and flowers, moderate in roots, and the lowest in stems and tendrils. CsMPK4 was located in the nucleus and cytoplasm, and it had a close relationship with CmMPK4 in muskmelon. The cucumber plants overexpressing CsMPK4 became stronger and shorter, with reduced length and quantity of tendrils. Moreover, the transgenic seedlings were more resistant to high temperatures, with decreased malondialdehyde (MDA) content and increased activities of peroxidase (POD) and superoxide dismutase (SOD) in young leaves. Furthermore, the protein-protein interaction between CsMPK4 and CsVQ10, a member of the valine-glutamine family, was confirmed by yeast two-hybrid and bimolecular fluorescence complementation (BiFC) assays. The results suggested that CsVQ10 cooperated with CsMPK4 in response to the high temperature stress in cucumber. This study laid a foundation for the further study on the stress response mechanism of CsMPK4 and the breeding of stress-resistant cucumber varieties.
Cucumis sativus/metabolism* ; Mitogen-Activated Protein Kinases/physiology* ; Plant Proteins/metabolism* ; Plants, Genetically Modified/metabolism* ; Gene Expression Regulation, Plant ; Stress, Physiological/genetics* ; Cloning, Molecular

Mercury (Hg)-contaminated soil poses a significant threat to the environment and human health. Hg-resistant microorganisms have the ability to survive under the stress of inorganic and organic Hg and effectively reduce Hg levels and toxicity. Compared to physical and chemical remediation methods, microbial remediation technologies have garnered increasing attention in recent years due to their lower cost, remarkable efficacy, and minimal environmental impact. This paper systematically elucidates the molecular mechanisms of Hg resistance in microbes, with a focus on their potential applications in phytoremediation of Hg-contaminated soils through plant-microbe interactions. Furthermore, it highlights the critical role of microbes in enhancing the effectiveness of transgenic plants for Hg remediation, aiming to provide a theoretical foundation and scientific basis for the bioremediation of Hg-contaminated soils.
Mercury/toxicity* ; Biodegradation, Environmental ; Soil Pollutants/isolation & purification* ; Soil Microbiology ; Plants, Genetically Modified/metabolism* ; Bacteria/genetics*

The fungal bioluminescence pathway (FBP) catalyzes the oxidation of endogenous caffeic acid to produce green bioluminescence through an enzymatic cascade. Genetic engineering of FBP into plants creates autoluminescent specimens that circumvent the substrate limitations of conventional reporter systems. These transgenic plants serve dual functions as aesthetic displays and versatile biosensing platforms, enabling applications in real-time gene expression monitoring, continuous environmental surveillance, and non-invasive bioimaging, offering novel opportunities for horticultural production, environmental conservation, and bioengineering applications. This review synthesizes current advances in plant FBP engineering and explores how machine learning approaches can optimize autoluminescent phenotypes, thereby accelerating innovation in agricultural biotechnology, environmental sensing, and synthetic biology applications.
Fungi/genetics* ; Plants, Genetically Modified/metabolism* ; Genetic Engineering ; Biosensing Techniques ; Luminescent Measurements ; Caffeic Acids/metabolism* ; Luminescence

Flowering and bolting are important agronomic traits in cruciferous crops such as Brassica juncea. Timely flowering can ensure the crop organ yield and quality, as well as seed propagation. The WRKY family plays an important role in regulating plant bolting and flowering, while the function and mechanism of WRKY12 in B. juncea remain unknown. To explore its function and mechanism in bolting and flowering of B. juncea, we cloned and characterized the BjuWRKY12 gene in B. juncea and found that its expression levels were significantly higher in flowers and inflorescences than in leaves. BjuWRKY12 belonged to the Ⅱc subfamily of the WRKY family, and subcellular localization indicated that the protein was located in the nucleus. Ectopic overexpression of BjuWRKY12 in transgenic lines promoted bolting and flowering, leading to significant increases in the expression levels of flowering integrators SOC1 and FUL. Furthermore, yeast one-hybrid and dual luciferase reporter system assays confirmed that BjuWRKY12 directly bound to the promoters of BjuSOC1 and BjuFUL, undergoing protein-DNA interactions. This discovery gives new insights into the regulation network and molecular mechanisms of BjuWRKY12, laying a theoretical foundation for the breeding of high-yield and high-quality varieties of B. juncea.
Mustard Plant/metabolism* ; Flowers/growth & development* ; Plant Proteins/physiology* ; Promoter Regions, Genetic/genetics* ; Gene Expression Regulation, Plant ; Plants, Genetically Modified/genetics* ; Transcription Factors/metabolism* ; MADS Domain Proteins/metabolism*