Zhongfeng Zhang

Ethylene Response Factor TERF1, Regulated by ETHYLENE-INSENSITIVE3-like Factors, Functions in Reactive Oxygen Species (ROS) Scavenging in Tobacco ( Nicotiana tabacum L.)

The phytohormone ethylene plays a crucial role in the production and accumulation of reactive oxygen species (ROS) in plants under stress conditions. Ethylene response factors (ERFs) are important ethylene-signaling regulators functioning in plant defense responses against biotic and abiotic stresses. However, the roles of ERFs during plant adapting to ROS stress have not yet been well documented. Our studies previously reported that a tomato ERF transcription factor TERF1 functions in the regulation of plant ethylene responses and stress tolerance. Here, we report our findings regarding the roles of TERF1 in ROS scavenging. In this study, we revealed that the transcription of TERF1 is regulated by upstream EIN3-like (EIN3, ethylene-insensitive 3) regulators LeEIL3 and LeEIL4 in tomato (Solanum lycopersicum), and is also inducible by exogenous applied ROS-generating reagents. Ectopic expression of TERF1 in tobacco promoted the expression of genes involved in oxidative stress responses, including carbonic anhydrase functioning in hypersensitive defense, catalase and glutathione peroxidase catalyzing oxidative reactions, and GDP-D-mannose pyrophosphorylase functioning in ascorbic acid biosynthesis, reduced the ROS content induced by ethylene treatment, and enhanced stress tolerance of tobacco seedlings to hydrogen peroxide (H2O2). Cumulatively, these findings suggest that TERF1 is an ethylene inducible factor regulating ROS scavenging during stress responses.

Solanesol: a review of its resources, derivatives, bioactivities, medicinal applications, and biosynthesis

Solanesol, which mainly accumulates in solanaceous crops, including tobacco, tomato, potato, eggplant, and pepper plants, is a long-chain polyisoprenoid alcohol compound with nine isoprene units. Chemical synthesis of solanesol is difficult; therefore, solanesol is primarily extracted from solanaceous crops, particularly tobacco leaves. In plants, solanesol exists in both free and esterified forms, and its accumulation is influenced by genetic and environmental factors. Solanesol is widely used in the pharmaceutical industry as an intermediate for the synthesis of ubiquinone drugs, such as coenzyme Q10 and vitamin K2. Solanesol possesses antibacterial, antifungal, antiviral, anticancer, anti-inflammatory, and anti-ulcer activities, and solanesol derivatives also have anti-oxidant and antitumour activities, in addition to other bioactivities. Solanesol derivatives can also be used for the treatment of cardiovascular disease, osteoporosis, acquired immune deficiency syndrome, and wound healing. Solanesol biosynthesis occurs in plastids of higher plants via the 2-C-methyl-d-erythritol-4-phosphate (MEP) pathway. The key enzymes in solanesol biosynthesis, including 1-deoxy-d-xylulose-5-phosphate synthase, 1-deoxy-d-xylulose-5-phosphate-reductoisomerase, isopentenyl pyrophosphate isomerase, and solanesyl diphosphate synthase, are also important regulators of the MEP pathway, and their overexpression is favourable for downstream metabolic flow, further promoting the synthesis of downstream metabolites, such as solanesol. Future studies should determine the pharmacokinetic properties of solanesol and its derivatives and investigate the metabolic pathways and regulatory mechanisms mediating solanesol biosynthesis, metabolic and genetic engineering of solanesol, the synthetic biology of solanesol, and the physiological role of solanesol. In the present review, we systematically summarise current knowledge on solanesol resources, derivatives, bioactivities and medicinal applications, metabolic pathways, and key biosynthetic enzymes.

Cytological Assessments and Transcriptome Profiling Demonstrate that Evodiamine Inhibits Growth and Induces Apoptosis in a Renal Carcinoma Cell Line

Chinese medicines are an important source of secondary metabolites with excellent antitumour activity. Evodia rutaecarpa, from the family Rutaceae, exhibits antitumour activity. Evodiamine (EVO), which was isolated from the fruit of E. rutaecarpa, exhibits robust antitumour activity. However, the antitumour mechanism of EVO remains unclear. In this study, we assessed the growth-inhibiting effect of EVO on two renal carcinoma cell lines. We found that EVO could change the morphology and decrease the viability and proliferation of cells in a time- and concentration-dependent manner in vitro. In addition, transcriptome analysis indicated that EVO can modulate the transcriptome of Caki-1 cells. In total, 7,243 differentially expressed genes were found, among which 3,347 downregulated genes and 3,896 upregulated genes were mainly involved in cell migration, apoptosis, cell cycle, and DNA replication. Furthermore, we demonstrated that EVO can cause apoptosis, arrest cells in the G2/M phase, and regulate the expression of apoptosis- and cell cycle-related genes in Caki-1 cells. Our study reveals the anticancer effects of EVO using cellular and molecular data, and indicates the potential uses of this compound as a resource to characterize the antitumour mechanisms of E. rutaecarpa.

Morphological Characteristics, Nutrients, and Bioactive Compounds of Zizania latifolia, and Health Benefits of Its Seeds

Zizania latifolia (tribe Oryzeae Dum., subfamily Oryzoideae Care, family Gramineae) is native to East Asian countries. The seeds of Z. latifolia (Chinese wild rice) have been consumed as a cereal in China for >3000 years. Z. latifolia forms swollen culms when infected with Ustilago esculenta, which is the second most-cultivated aquatic vegetable in China. The current review summarizes the nutrients and bioactive compounds of Z. latifolia, and health benefits of its seeds. The seeds of Z. latifolia contain proteins, minerals, vitamins, and bioactive compounds, the activities of which—for example, antioxidant activity—have been characterized. Various health benefits are associated with their consumption, such as alleviation of insulin resistance and lipotoxicity, and protection against cardiovascular disease. Chinese wild rice may be used to prevent and treat metabolic disease, such as diabetes, obesity, and cardiovascular diseases. Various compounds were isolated from the swollen culm, and aerial parts of Z. latifolia. The former suppresses osteoclast formation, inhibits growth of rat glioma cells, and may act as antioxidants and immunomodulators in drugs or foods. The latter exerts anti-fatigue, anti-inflammatory, and anti-allergic effects. Thus, Z. latifolia may be used to produce nutraceuticals and functional foods.

Chemical Basis of the Fungicidal Activity of Tobacco Extracts against Valsa mali

Under pressure from social criticism and an unclear future, tobacco researchers have begun to seek alternative uses for the product. Here, we present our study on isolating tobacco compounds with fungicidal activity, which could be used as plant-derived pesticides. Using Valsa mali as the target fungus, agar plate tests were conducted to evaluate the fungicidal activity of various tobacco extracts, including tobacco leaves extracts prepared with different solvents, extracts of different tobacco cultivars, and samples from different tobacco organs. Fungal growth morphology was used as the criterion to evaluate the fungicidal activity of tobacco extracts. Correlation analyses between the fungicidal activities and the chemical components of tobacco extracts indicated the major chemical constituents with fungicidal activity. Then, the active compounds were isolated and their effects on the ultra-microstructures of V. mali was analyzed using scanning- and transmission-electron microscopy. The results suggested that tobacco extracts prepared with solvents of weaker polarity had higher fungicidal activity, and the inhibitory activity of tobacco extracts against V. mali was also cultivar dependent. Furthermore, the fungicidal effects of tobacco flower extracts were higher than those of the leaf extracts. Chemical analysis indicated that cembranoids were the main fungicidal substances, which act by destroying the endometrial structure of the fungus. Tobacco cembranoids at 80 μg/mL could completely inhibit the growth of V. mali, with an EC50 value of 13.18 μg/mL. Our study therefore suggests that tobacco leaves and inflorescences are excellent plant resources for the biological control of V. mali.

Solanesol Biosynthesis in Plants

Solanesol is a non-cyclic terpene alcohol composed of nine isoprene units that mainly accumulates in solanaceous plants. Solanesol plays an important role in the interactions between plants and environmental factors such as pathogen infections and moderate-to-high temperatures. Additionally, it is a key intermediate for the pharmaceutical synthesis of ubiquinone-based drugs such as coenzyme Q10 and vitamin K2, and anti-cancer agent synergizers such as N-solanesyl-N,N′-bis(3,4-dimethoxybenzyl) ethylenediamine (SDB). In plants, solanesol is formed by the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway within plastids. Solanesol’s biosynthetic pathway involves the generation of C5 precursors, followed by the generation of direct precursors, and then the biosynthesis and modification of terpenoids; the first two stages of this pathway are well understood. Based on the current understanding of solanesol biosynthesis, we here review the key enzymes involved, including 1-deoxy-d-xylulose 5-phosphate synthase (DXS), 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), isopentenyl diphosphate isomerase (IPI), geranyl geranyl diphosphate synthase (GGPPS), and solanesyl diphosphate synthase (SPS), as well as their biological functions. Notably, studies on microbial heterologous expression and overexpression of key enzymatic genes in tobacco solanesol biosynthesis are of significant importance for medical uses of tobacco.

Genome-Wide Analysis of Long Non-Coding RNAs in Potato and Their Potential Role in Tuber Sprouting Process

Sprouting is a key factor affecting the quality of potato tubers. The present study aimed to compare the differential expression of long non-coding RNAs (lncRNAs) in the apical meristem during the dormancy release and sprouting stages by using lncRNA sequencing. Microscopic observations and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed the changes in the morphology and expression of lncRNAs in potato tubers during sprouting. Meristematic cells of potato tuber apical buds divided continuously and exhibited vegetative cone bulging and vascularisation. In all, 3175 lncRNAs were identified from the apical buds of potato tubers, among which 383 lncRNAs were up-regulated and 340 were down-regulated during sprouting. The GO enrichment analysis revealed that sprouting mainly influenced the expression of lncRNAs related to the cellular components of potato apical buds (e.g., cytoplasm and organelles) and cellular metabolic processes. The KEGG enrichment analysis also showed significant enrichment of specific metabolic pathways. In addition, 386 differentially expressed lncRNAs during sprouting were identified as putative targets of 235 potato miRNAs. Quantitative real-time polymerase chain reaction results agreed with the sequencing data. Our study provides the first systematic study of numerous lncRNAs involved in the potato tuber sprouting process and lays the foundation for further studies to elucidate their precise functions.

Organ- and Growing Stage-Specific Expression of Solanesol Biosynthesis Genes in Nicotiana tabacum Reveals Their Association with Solanesol Content

Solanesol is a noncyclic terpene alcohol that is composed of nine isoprene units and mainly accumulates in solanaceous plants, especially tobacco (Nicotiana tabacum L.). In the present study, RNA-seq analyses of tobacco leaves, stems, and roots were used to identify putative solanesol biosynthesis genes. Six 1-deoxy-d-xylulose 5-phosphate synthase (DXS), two 1-deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), two 2-C-methyl-d-erythritol 4-phosphate cytidylyltransferase (IspD), four 4-diphosphocytidyl-2-C-methyl-d-erythritol kinase (IspE), two 2-C-methyl-d-erythritol 2,4-cyclo-diphosphate synthase (IspF), four 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate synthase (IspG), two 1-hydroxy-2-methyl-2-(E)-butenyl 4-diphosphate reductase (IspH), six isopentenyl diphosphate isomerase (IPI), and two solanesyl diphosphate synthase (SPS) candidate genes were identified in the solanesol biosynthetic pathway. Furthermore, the two N. tabacum SPS proteins (NtSPS1 and NtSPS2), which possessed two conserved aspartate-rich DDxxD domains, were highly homologous with SPS enzymes from other solanaceous plant species. In addition, the solanesol contents of three organs and of leaves from four growing stages of tobacco plants corresponded with the distribution of chlorophyll. Our findings provide a comprehensive evaluation of the correlation between the expression of different biosynthesis genes and the accumulation of solanesol, thus providing valuable insight into the regulation of solanesol biosynthesis in tobacco.

Overexpression of secreted sucrose isomerase in Yarrowia lipolytica and its application in isomaltulose production after immobilization

Isomaltulose production by bacterial fermentation was limited, due to generation of undesirable products and reduced yields. Isomaltulose production using sucrose isomerase (SIase) catalyzed methods was expected to be more applicable, but was hampered by low SIase activity and lack of a secreted SIase producer. Here, we aimed to obtain high levels of secreted SIase by overexpressing the SIase gene from Pantoea dispersa UQ68J in Yarrowia lipolytica, a successful host for efficient secretory expression, with a newly characterized strong constitutive promoter. After optimization of the culture medium, the engineered strain JD secreted SIase with an activity of 49.3 U/mL. The recombinant SIase was effectively immobilized onto polyvinyl alcohol-alginate, and the enzymatic activity recovery rate was up to 82.4%. The stability of the SIase was significantly improved by immobilization. Batch production of isomaltulose catalyzed by the immobilized SIase was performed under optimal conditions, generating 620.7 g/L isomaltulose with a yield of 0.96 g/g. The conversion rate of sucrose after 13 batches remained above 90%. These results demonstrated that the proposed SIase expression and immobilization method was promising in the industrial production of isomaltulose.

The mitochondrial genome of Arthrinium arundinis and its phylogenetic position within Sordariomycetes

Arthrinium arundinis is a common pathogen in nature, although its molecular taxonomic status has never been reported. Herein, we described the complete mitochondrial (mt) genome of A. arundinis, which is a circular DNA molecule with 48,975 bp in length; its A + T content is 72.04%. The mitogenome2, 23 tRNAs comprising 14 amino acids, 9 genes coding for proteins related to oxidative phosphorylation [nicotinamide adenine dinucleotide (nad) 1-5, nad4L, cytochrome b (cob), and cytochrome oxidase (cox) 1-2)], 3 ATP synthase subunits (atp6, atp8, and atp9), and 7 hypothetical proteins (orf73, orf143, orf252, orf266, orf328, orf341, and orf372). Phylogenetic analyses indicated that A. arundinis clustered with the members of the order Xylariales. Genome structure analyses showed that there are three blocks located in the mitogenome, including rns-rnl, nad2-nad5, and cob-atp6. The A. arundinis mitogenome presented features different from those of species in Xylariales, especially for the regions coding trns (trnR-trnY). In addition, comparison of the gene orders from species in Sordariomycetes revealed that although all coding regions are located on the same strand in most Sordariomycetes mitogenomes, several genes from A. arundinis presented reversed positions and co-localization of genes (i.e., nad1, nad4, and cox1).