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Solanesol, which accumulates predominantly in the leaves of tobacco plants, has medically important bioactive properties. To investigate the genetic basis of solanesol in tobacco (Nicotiana tabacum), the solanesol contents of 222 accessions, 206 individuals from an N. tabacum Maryland609 (low-solanesol) × K326 (high-solanesol) F2 population and their corresponding F1 self-pollinations, were determined using ultra-performance liquid chromatography. Genome-wide quantitative trait locus (QTL) and association analysis were performed to identify QTLs and markers associated with solanesol content based on simple sequence repeat molecular markers. A total of 12 QTLs underlying solanesol content were mapped to seven linkage groups (LGs), with three of the QTLs (QTL3-1, QTL21-6, and QTL23-3) explaining 5.19–10.05% of the phenotypic variation. Association analysis revealed 38 significant marker-trait associations in at least one environment. The associations confirmed the QTLs located on LG3, LG10, LG14, LG21, and LG23, while new elite makers were located on 11 additional LGs, each explaining, respectively, 5.16–20.07% of the phenotypic variation. The markers LG14-PT54448, LG10-PT60114-2, LG10-PT60510, LG10-PT61061, and LG-21PT20388 may be useful for molecular-assisted selection of solanesol content in tobacco leaves. These results increase our understanding of the inheritance of solanesol-associated genes and will contribute to molecular-assisted breeding and further isolation of regulatory genes involved in solanesol biosynthesis in tobacco leaves. [ABSTRACT FROM AUTHOR]

To explore the multipurpose utilization of tobacco germplasm resources, 80 representative air/sun-cured tobacco germplasms were used as experimental materials to determine the composition and content of the diterpenoids of glandular trichome secretions using ultra-performance liquid chromatography (UPLC). Correlation analysis, cluster analysis, and principal component analysis (PCA) were used to comprehensively evaluate 80 air/sun-cured tobacco germplasms. The results are as follows: (1) 11 chromatographic peaks (Peak1–Peak11) were detected by UPLC, and the coefficient of variation of their contents ranged from 26.3 to 143%. (2) Correlation analysis showed that alpha-cembratriene-diol (α-CBT-diol) and beta-cembratriene-diol (β-CBT-diol) had the highest correlation coefficients (0.97), showing a significantly negative correlation with cis-abienol and a significantly positive correlation with the other diterpenoids. (3) PCA showed that the cumulative contribution rate of the three principal components was 75.70%, and the diterpenoid-rich germplasms were ranked in the following order: X40 (Maiduo) > X48 (Jianpingpiaoba) > X58 (Mianzhu) > X54 (Shifangpipaliu) > X63 (Xuejia5) > X41 (Tangpeng) > X29 (OLOR) > X73 (Criollo) > X44 (Tiebanqing) > X70 (Nicaragua Changxin). The diterpenoid content of X36 was the lowest. These results provide excellent germplasm for the extraction and exploitation of the diterpenoids and for genetic studies of their metabolism. [ABSTRACT FROM AUTHOR]

Cembranoids produced by tobacco glandular trichomes have bioactivities in resistance to insect pests and pathogens. Cembratrien-ol synthase (CBTS) plays a key role in the biosynthesis of cembranoids and directly determines the cembranoid content in tobacco. This study examined the effect of changing CBTS1 expression on tobacco resistance to the insect pest Spodoptera frugiperda and oomycete pathogen Phytophthora nicotianae. The CDS sequence of CBTS1 was cloned into gene overexpression and silencing vectors and introduced into tobacco (Nicotiana tabacum L. cv. TN90) to obtain CBTS1-overexpression plants (CBTS1-OE) and CBTS1-silenced plants (CBTS1-RI). Compared with control plants, the content of cembratrien-ol (CBT-ol) was increased 4.48 times in the CBTS1-OE plants but decreased by 68% in the CBTS1-RI plants, while that of cembratrien-diol (CBT-diol) was increased 3.17 times in the CBTS1-OE plants but decreased by 76% in the CBTS1-RI plants. The S. frugiperda resistance of transgenic tobacco plants was evaluated by in vitro toxicity test, and the results showed that the resistance of CBTS1-OE plants to S. frugiperda was significantly improved but that of CBTS1-RI plants was reduced. The P. nicotianae resistance of transgenic tobacco plants was assessed by the detached leaf assay, and the results showed that the resistance of CBTS1-OE plants to P. nicotianae was enhanced, while that of CBTS1-RI plants was attenuated. Further gene expression analysis showed that overexpression of CBTS1 increased the expression of the pathogen-related gene PR-1a, while silencing of CBTS1 decreased its expression. This study demonstrated that manipulating the expression of CBTS1 could change the cembranoid content in tobacco plants and alter their resistance to both insect pests and oomycete pathogens. [ABSTRACT FROM AUTHOR]

The effects of overexpression of the thioredoxin-like protein CDSP32 (Trx CDSP32) on reactive oxygen species (ROS) metabolism in tobacco leaves exposed to cadmium (Cd) were studied by combining physiological measures and proteomics technology. Thus, the number of differentially expressed proteins (DEPs) in plants overexpressing the Trx CDSP32 gene in tobacco (OE) was observed to be evidently lower than that in wild-type (WT) tobacco under Cd exposure, especially the number of down-regulated DEPs. Cd exposure induced disordered ROS metabolism in tobacco leaves. Although Cd exposure inhibited the activities of superoxide dismutase (SOD), catalase (CAT), and l -ascorbate peroxidase (APX) and the expression of proteins related to the thioredoxin-peroxiredoxin (Trx-Prx) pathway, the increase in the activities of peroxidase (POD), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), and glutathione S -transferase (GST) and their protein expression levels played an important role in the physiological response to Cd exposure. Notably, Trx CDSP32 was observed to alleviate the decrease in the expression and activities of SOD and CAT caused by Cd exposure and enhance the function of POD. Trx CDSP32 was observed to increase the H 2 O 2 scavenging capacity of the ascorbic acid-glutathione (AsA-GSH) cycle and Trx-Prx pathway under Cd exposure, and it can especially regulate 2-Cys peroxiredoxin (2-Cys Prx) protein expression and thioredoxin peroxidase (TPX) activity. Thus, overexpression of the Trx CDSP32 gene can alleviate the oxidative damage that occurs in tobacco leaves under Cd exposure by modulating antioxidant defense systems. • Trx CDSP32 alleviated Cd-induced oxidative damage in tobacco leaves. • Trx CDSP32 enhanced the function of antioxidant enzymes such as SOD, POD and CAT. • Trx CDSP32 increased the ability of AsA-GSH cycle and Trx-Prx pathway to remove H 2 O 2. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of 2-Cys Prx gene inhibition on photochemical reaction and reactive oxygen species (ROS) metabolism under high temperature (35°C) with low light (HT + LL) or high temperature with high light (HT + HL) in tobacco. The results showed that HT significantly increased the production of O 2 ⋅ − and H2O2 compared with CK (25°C). Particularly, the oxidative damage of RNAi plants was significantly greater than that of wild type (WT) under HT + HL treatment, possibly due to the inhibition of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities. HT treatment inhibited the photosystem II (PSII) activity, and the oxygen evolution complex (OEC) was the main injury site. Notably, the photosystem I (PSI) activity of WT and RNAi plants did not change significantly under HT + LL treatment compared with CK. Although the PSI activity of WT and RNAi plants decreased significantly under HT + HL treatment, there was no significant difference between WT and RNAi plants. Collectively, these findings indicate that high light increases the photoinhibition of PSII and PSI and oxidative damage under high-temperature stress. The results also revealed that 2-Cys Prx plays a crucial role in alleviating oxidative damage and PSII photoinhibition under high-temperature stress in tobacco. [ABSTRACT FROM AUTHOR]

To clarify the effects of plant growth promoting rhizobacteria (PGPR)on growth promotion and disease resistance of flue-cured tobacco, potential roles of previously isolated Bacillus velezensis F10 were studied through pot and plot experiments to investigate its growth promotion and control effects on tobacco bacterial wilt. The results showed that the growth of roots and aerial parts of tobacco plants under the biocontrol bacterium F10 treatment were significantly better than that of the control, and the activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) in tobacco leaves increased. The control effects of biocontrol bacterium F10 on tobacco bacterial wilt in pot and plot experiments were 60.49% and 54.91% respectively. The agronomic traits of flue-cured tobacco in fields treated with biocontrol bacterium F10 were significantly better than those of the control. The yield, output value, average price, proportion of high grade leaves, and proportion of high-to-mid grade leaves increased by 11.82%, 31.46% and 13.17% respectively. Biocontrol bacterium F10 has growth promoting effect on flue-cured tobacco and has good control effect against tobacco bacterial wilt, which significantly promotes the economic benefits of flue-cured tobacco. [ABSTRACT FROM AUTHOR]

Jasmonate (JA)-induced plant senescence has been mainly studied with a dark/starvation-promoted system using detached leaves; yet, the induction of whole-plant senescence by JA remains largely unclear. This work reports the finding of a JA-induced whole-plant senescence of tobacco under light/non-starvation conditions and the investigation of underlying regulations. Methyl jasmonate (MeJA) treatment induces the whole-plant senescence of tobacco in a light-intensity–dependent manner, which is suppressed by silencing of NtCOI1 that encodes the receptor protein of JA-Ile (the bioactive derivative of JA). MeJA treatment could induce the senescence-specific cysteine protease gene SAG12 and another cysteine protease gene SAG-L1 to high expression levels in the detached leaf patches under dark conditions but failed to induce their expression in tobacco whole plants under light conditions. Furthermore, MeJA attenuates the RuBisCo activase (RCA) level in the detached leaves but has no effect on this protein in the whole plant under light conditions. A genome-wide transcriptional assay also supports the presence of a differential regulatory pattern of senescence-related genes during MeJA-induced whole-plant senescence under non-starvation conditions and results in the finding of a chlorophylase activity increase in this process. We also observed that the MeJA-induced senescence of tobacco whole plants is reversible, which is accompanied by a structural change of chloroplasts. This work provides novel insights into JA-induced plant senescence under non-starvation conditions and is helpful to dissect the JA-synchronized process of whole-plant senescence. [ABSTRACT FROM AUTHOR]

We examined the effects of Cd and Zn exposure on the photosynthetic function and the tolerant mechanisms of ROS metabolism in tobacco leaves. The results showed that the photosynthesis inhibition caused by Cd exposure was due to the limitation of both stomatal and non-stomatal factors, while Zn exposure only showed a significant effect on the Gs of tobacco leaves. Cd increased the generation rate of O2•– and the content of H2O2, but Zn did not lead to the ROS burst. Cd enhanced the POD activity, but inhibited SOD and CAT activities. The activities of SOD and POD significantly increased under Zn exposure. Cd inhibited the activity and expression of APX. The up regulation of GPX, GR and GST expression and the increase of their activities also play a positive role in the adaptation to Cd. Although Zn inhibited the activities of APX and GPX, it had little effect on other enzyme activities and protein expression in AsA-GSH cycle. TPX and TrxR activities, Trx-Prx pathway-related proteins are very sensitive to Cd. However, only PrxQ and 2-Cys Prx BAS1, which are located in chloroplast, and Trx-HFC164 were significantly down-regulated in Trx-Prx pathway under Zn exposure. [ABSTRACT FROM AUTHOR]

The effects of exogenous γ-glutamic acid (GABA) on photosynthetic gas exchange capacity, PSII function, proline (Pro) synthesis and ROS metabolism of tobacco leaves under cadmium (Cd) stress were studied. The results showed that both stomatal and non-stomatal factors were the important factors to limit the photosynthetic capacity of tobacco leaves under Cd stress. Pro accumulation and glutathione (GSH) content increase are the important ways for tobacco leaves to adapt to Cd stress. Exogenous GABA significantly increased the stability of oxygen-evolving complex (OEC) and the electron transfer rate of PSII in tobacco leaves under Cd stress, and increased Gs and Pn in varying degrees. Exogenous GABA also increased the expression of P5CS and P5CR genes in tobacco leaves under Cd stress, thus promoting Pro accumulation. In conclusion, 0.5 mmol·L−1 exogenous GABA can not only improve the carbon assimilation ability by increasing the Gs, but also alleviate the oxidative damage by promoting the synthesis and accumulation of Pro and GSH, and improve the stability of photosynthetic function of tobacco leaves under Cd stress. [ABSTRACT FROM AUTHOR]

To reveal the mechanism of photosynthesis inhibition by infection and the response of the MAPK signaling pathway to pathogen infection, tobacco leaves were inoculated with Pseudomonas syringae pv. tabaci (Pst), and the effects of Pst infection on photosynthesis of tobacco leaves were studied by physiological and proteomic techniques, with a focus on MAPK signaling pathway related proteins. Pst infection was observed to lead to the degradation of chlorophyll (especially Chl b) in tobacco leaves and the down-regulation of light harvesting antenna proteins expression, thus limiting the light harvesting ability. The photosystem II and I (PSII and PSI) activities were also decreased, and Pst infection inhibited the utilization of light and CO 2. Proteomic analyses showed that the number of differentially expressed proteins (DEPs) under Pst infection at 3 d were significantly higher than at 1 d, especially the number of down-regulated proteins. The KEGG enrichment of DEPs was mainly enriched in the energy metabolism processes such as photosynthesis antenna proteins and photosynthesis. The down-regulation of chlorophyll a - b binding protein, photosynthetic electron transport related proteins (e.g., PSII and PSI core proteins, the Cytb6/f complex, PC, Fd, FNR), ATP synthase subunits, and key enzymes in the Calvin cycle were the key changes associated with Pst infection that may inhibit tobacco photosynthesis. The effect of Pst infection on the PSII electron acceptor side was significantly greater than that on the PSII donor side. The main factor that decreased the photosynthetic ability of tobacco leaves with Pst infection at 1 d may be the inhibition of photochemical reactions leading to an insufficient supply of ATP, rather than decreased expression of enzymes involved in the Calvin cycle. At 1 d into Pst infection, the PSII regulated energy dissipation yield Y(NPQ) may play a role in preventing photosynthetic inhibition in tobacco leaves, but the long-term Pst infection significantly inhibited Y(NPQ) and the expression of PsbS proteins. Proteins involved in the MAPK signaling pathway were up-regulated, suggesting the MAPK signaling pathway was activated to respond to Pst infection. However, at the late stage of Pst infection (at 3 d), MAPK signaling pathway proteins were degraded, and the defense function of the MAPK signaling pathway in tobacco leaves was damaged. • The effects of Pst infection on photosynthesis of tobacco leaves were studied by physiological and proteomic techniques. • The KEGG enrichment of DEPs was mainly enriched in photosynthesis antenna proteins and photosynthesis. • The effect of Pst infection on the PSII electron acceptor side was significantly greater than that on the PSII donor side. • At the early stage of Pst infection, regulatory energy dissipation and the MAPK signaling pathway were activated. [ABSTRACT FROM AUTHOR]

Tobacco alkaloid metabolism is regulated by various transcription factors (TFs). Here, we have characterized a non- NIC2 locus gene, Ethylene Response Factor 91 (ERF91), function in regulation of alkaloid accumulation in tobacco. NtERF91 was preferentially expressed in roots and induced by jasmonic acid. Additionally, NtERF91 was able to in vitro bind to the NtPMT2 and NtQPT2 promoters via directly targeting the GCC-box elements and transactivate NtQPT2 gene expression. Ectopic overexpression of NtERF91 not only increased the expression of most nicotine biosynthetic genes, but also altered alkaloid accumulation profile, resulting in dramatically anatabine accumulation. We conclude that NtERF91 plays an overlapped but distinct role in regulating tobacco alkaloid accumulations. • NtERF91 locates at the aside of a NIC2-like NtERF gene cluster in tobacco genome. • NtERF91 is coexpressed with nicotine biosynthetic and regulatory genes in roots. • NtERF91 is able to transactivate the expression of nicotine biosynthetic genes. • Overexpression of NtERF91 significantly increases alkaloid accumulations, particularly in anatabine. [ABSTRACT FROM AUTHOR]

Brown spot of tobacco (Nicotiana tabacum L.), a fungal disease caused by Alternaria alternata, is widely spread across the world. In the present study, the physiological and transcriptional characteristics correlated with brown spot resistance were investigated using the resistant cultivar Beinhart 1000‐1 and a susceptible cultivar K326. The physiological assays revealed that Beinhart 1000‐1 was more sensitive to jasmonate (JA) than K326 in seed germination and root elongation assays. MYC2, a key regulator of the JA‐signaling pathway, exhibited a much higher expression level in Beinhart 1000‐1 than in K326 after pathogen challenge with A. Alternata or phytohormone treatment with JA, supporting the higher JA sensitivity of Beinhart 1000‐1. The transcriptional analyses showed that brown spot infection could provoke the expression of a set pathogenesis‐related (PR) genes and transcription factor genes from ethylene response factor (ERF), WRKY, and bHLH families, which are potentially involved in pathogen response. Furthermore, a number of these genes were induced to higher transcription levels by JA in Beinhart 1000‐1 than in K326. Cumulatively, this study revealed a set of JA‐mediated physiological and molecular factors that determine the brown spot resistance of tobacco and may provide cues for resistance breeding. [ABSTRACT FROM AUTHOR]

Basic helix-loop-helix (bHLH) transcription factor MYC2 regulates plant growth and development in many aspects through the jasmonic acid (JA) signaling pathway, while the role of MYC2 in plant carbohydrate metabolism has not been reported. Here, we generated NtMYC2a-overexpressing (NtMYC2a-OE) and RNA-interference-mediated knockdown (NtMYC2a-RI) transgenic plants of tobacco (Nicotiana tabacum L. cv. TN90) to investigate the role of NtMYC2a in carbohydrate metabolism and pollen development. Results showed that NtMYC2a regulates the starch accumulation and the starch-sugar conversion of floral organs, especially in pollen. The RT-qPCR analysis showed that the expression of starch-metabolic-related genes, AGPs, SS2 and BAM1, were regulated by NtMYC2a in the pollen grain, anther wall and ovary of tobacco plants. The process of pollen maturation was accelerated in NtMYC2a-OE plants and was delayed in NtMYC2a-RI plants, but the manipulation of NtMYC2a expression did not abolish the pollen fertility of the transgenic plants. Intriguingly, overexpression of NtMYC2a also enhanced the soluble carbohydrate accumulation in tobacco ovaries. Overall, our results demonstrated that the bHLH transcription factor NtMYC2a plays an important role in regulating the carbohydrate metabolism during pollen maturation in tobacco. [ABSTRACT FROM AUTHOR]

Ethylene responsive factors (ERFs) are important plant-specific transcription factors, some of which have been demonstrated to interact with the ethylene-responsive GCC box and the dehydration-responsive element (DRE); however, data on the roles of ERF proteins in connection with various signaling pathways are limited. In this research, we used the GCC box, an essential cis-acting element responsive to ethylene and methyl jasmonate (MeJA), as bait in a yeast one-hybrid system to isolate transcription factors from tomato (Lycopersicon esculentumMill.). One of the cDNAs, which was designatedJasmonate and Ethylene Response Factor 1(JERF1), encodes an ERF protein, containing a conserved ERF DNA-binding motif and functioning as a transcriptional activator in yeast through targeting to the nucleus in onion (Allium cepaL.) epidermal cells. Biochemical analysis revealed that JERF1 bound not only to the GCC box but also to the DRE sequence. Expression of theJERF1gene in tomato was induced by ethylene, MeJA, abscisic acid (ABA) and salt treatment, indicating that JERF1 might act as a connector among different signal transduction pathways. Further research with transgenicJERF1tobacco (Nicotiana tabacumL.) plants indicated that overexpressingJERF1activated expression of GCC box-containing genes such asosmotin,GLA,Prb-1bandCHN50under normal growth conditions, and subsequently resulted in enhanced tolerance to salt stress, suggesting that JERF1 modulates osmotic tolerance by activation of downstream gene expression through interaction with the GCC box or DRE. [ABSTRACT FROM AUTHOR]

The interaction between ethylene and osmotic stress pathways modulates the expression of the genes relating to stress adaptation; however, the mechanism is not well understood. In this paper, we report a novel ethylene responsive factor, tomato ethylene responsive factor 1 (TERF1), that integrates ethylene and osmotic stress pathways. Biochemical analysis indicated that TERF1 binds to the GCC box (an element responsive to ethylene) and to the dehydration responsive element, which is responsive to the osmoticum. Expression of TERF1 was induced by ethylene and NaCl treatment. Under normal growth conditions, overexpression of TERF1 in tobacco activated the expression of GCC box-containing pathogen related genes and also caused the typical ethylene triple response. Further investigation indicated that transgenic TERF1 tobacco exhibited salt tolerance, suggesting that TERF1 might function as a linker between the ethylene and osmotic stress pathways. [Copyright &y& Elsevier]

Thioredoxin-like protein CDSP32 (Trx CDSP32), a thioredoxin-like (Trx-like) protein located in the chloroplast, can regulate photosynthesis and the redox state of plants under stress. In order to examine the role of Trx CDSP32 in the photosynthetic apparatus of plants exposed to cadmium (Cd), the effects of Trx CDSP32 on photosynthetic function and photoprotection in tobacco leaves under Cd exposure were studied using a proteomics approach with wild-type (WT) and Trx CDSP32 overexpression (OE) tobacco plants. Cd exposure reduced stomatal conductance, blocked PSII photosynthetic electron transport, and inhibited carbon assimilation. Increased water use efficiency (WUE), cyclic electron flow (CEF) of the proton gradient regulation 5 pathway (PGR5-CEF), and regulated energy dissipation [Y(NPQ)] are important mechanisms of Cd adaptation. However, CEF of the NAD(P)H dehydrogenase pathway (NDH-CEF) was inhibited by Cd exposure. Relative to control conditions, the expression levels of violaxanthin de-epoxidase (VDE) and photosystem II 22 kDa protein (PsbS) in OE leaves were significantly increased under Cd exposure, but those in WT leaves did not change significantly. Moreover, the expression of zeaxanthin epoxidase (ZE) under Cd exposure was significantly higher than that in WT leaves. Thus, Trx CDSP32 increased Y(NPQ) and alleviated PSII photoinhibition under Cd exposure. Trx CDSP32 not only increased PGR5-like protein 1A and 1B expression, but also alleviated the down-regulation of NAD(P)H-quinone oxidoreductase subunits induced by Cd exposure. Thus, Trx CDSP32 promotes CEF in Cd-exposed tobacco leaves. Thus, Trx CDSP32 alleviates the Cd-induced photoinhibition in tobacco leaves by regulating two photoprotective mechanisms: CEF and xanthophyll cycle-dependent energy dissipation. [Display omitted] • Cd exposure reduced the stomatal conductance, blocked PSII electron transport, and inhibited carbon assimilation. • Trx CDSP32 alleviated the photoinhibition by regulating photoprotective mechanisms. • Trx CDSP32 up regulated PsbS and VDE expression, and promoted the regulated energy dissipation. • Trx CDSP32 increased in PGR5-CEF, and alleviated the decrease of NDH-CEF caused by Cd exposure. [ABSTRACT FROM AUTHOR]

Solanesol, an aliphatic terpene alcohol composed of nine isoprene units, is mainly found in solanaceous plants. Particularly, tobacco (Nicotiana tabacum), belonging to the Solanaceae family, is the richest plant source of solanesol, and its leaves have been regarded as the ideal material for solanesol extraction. Since the discovery of solanesol in tobacco, significant progress has been achieved in research on solanesol's bioactivities, medicinal value, accumulation, extraction technology, and determination methods. Solanesol possesses strong free radical absorption ability and antioxidant activity owing to the presence of several non-conjugated double bonds. Notably, solanesol's anti-inflammatory, neuroprotective, and antimicrobial activities have been previously demonstrated. Solanesol is a key intermediate in the synthesis of coenzyme Q10, vitamin K2, and the anticancer agent synergiser N-solanesyl-N,N′-bis(3,4-dimethoxybenzyl) ethylenediamine. Other applications of solanesol include solanesol derivative micelles for hydrophobic drug delivery, solanesol-derived scaffolds for bioactive peptide multimerization, and solanesol-anchored DNA for mediating vesicle fusion. Solanesol accumulation in plants is influenced by genetic and environmental factors, including biotic stresses caused by pathogen infections, temperature, illumination, and agronomic measures. Seven extraction technologies and seven determination methods of solanesol are also systematically summarized in the present review. This review can serve as a reference for solanesol's comprehensive application. [ABSTRACT FROM AUTHOR]

Cembranoids are carbocyclic diterpenes comprising four isoprene units and are natural products with a parent skeleton consisting of a 14-membered ring. They have gained wide interest in recent years and are a major hotspot in the research of natural product chemistry. Since 1962, various tobacco cembranoid diterpenes have been identified. This review systematically discusses and summarises the excellent antimicrobial, insecticidal, cytotoxic and neuroprotective activities of tobacco cembranoid diterpenes. These compounds show potential to be developed as botanical fungicides, cytotoxic drugs and drugs for the treatment of human immunodeficiency virus, Alzheimer's disease, Parkinson's disease, and other neurodegenerative diseases. However, there are relatively few studies on the structure–activity relationship (SAR) of tobacco cembranoid diterpenes. Therefore, future studies should focus on their structural modification, SAR and biogenic relationships. [ABSTRACT FROM AUTHOR]

Solanesol is a terpene alcohol composed of nine isoprene units that mainly accumulates in solanaceous plants, especially tobacco (Nicotiana tabacum). The present study aimed to investigate the regulation of solanesol accumulation in tobacco leaves induced by moderately high temperature (MHT). Exposure to MHT resulted in a significant increase in solanesol content, dry weight, and net photosynthetic rate in tobacco leaves. In MHT-exposed tobacco leaves, 492 and 1440 genes were significantly up- and downregulated, respectively, as revealed by RNA-sequencing. Functional enrichment analysis revealed that most of the differentially expressed genes (DEGs) were mainly related to secondary metabolite biosynthesis, metabolic pathway, carbohydrate metabolism, lipid metabolism, hydrolase activity, catalytic activity, and oxidation-reduction process. Moreover, 122 transcription factors of DEGs were divided into 22 families. Significant upregulation of N. tabacum 3-hydroxy-3-methylglutaryl-CoA reductase (NtHMGR), 1-deoxy-d-xylulose 5-phosphate reductoisomerase (NtDXR), geranylgeranyl diphosphate synthase (NtGGPS), and solanesyl diphosphate synthase (NtSPS) and significant downregulation of N. tabacum 1-deoxy-d-xylulose 5-phosphate synthase (NtDXS) and farnesyl diphosphate synthase (NtFPS) transcription upon MHT exposure were monitored by quantitative real-time PCR (qRT-PCR). This study indicated that solanesol accumulation in tobacco leaves can be manipulated through regulation of the environmental temperature and established a basis for further elucidation of the molecular mechanism of temperature regulation of solanesol accumulation. [ABSTRACT FROM AUTHOR]

Cembranoids are a group of natural diterpenoid compounds with pharmaceutical potentials, and the cembratriene-diols produced by Nicotiana (tobacco) species display activities in anti-nicotine addiction and neuron protection. Although the enzymes catalyzing cembratriene-diols' formation in tobacco have been investigated, the regulatory mechanism underlying this physiological process remains unknown. This study has investigated the roles of phytohormone jasmonic acid (JA) in regulating cembratriene-diol formation in N. tabacum cv. TN90 and found that JA and COI1, the receptor protein of the bioactive derivative of JA (i.e., JA-Ile), display critical roles in regulating cembratriene-diols' formation and the expression of cembranoid synthetic genes CBTS, P450 and NtLTP1. Further studies showed that over-expressing either the gene encoding bHLH transcription factor MYC2a or that encoding MYB transcription factor MYB305 could upregulate the cembranoid synthetic genes and enhance the cembranoid production in plants with dysfunction of COI1. Further studies suggest that COI1 and its downstream regulators MYC2a and MYB305 also modulate the trichome secretion, which is correlated with cembranoid formation. Taken together, this study has demonstrated a critical role of JA-signaling components in governing the cembratriene-diol formation and the transcription of cembratriene-diol synthetic genes in tobacco. Findings in this study are of great importance to reveal the molecular regulatory mechanism underlying cembranoid synthesis. [ABSTRACT FROM AUTHOR]

To reveal the response and adaptative mechanism of plants to the organic pollutants PBDEs, physiological and transcriptomic techniques were used to study the effects of exposure to BDE47 and BDE209 on tobacco (Nicotiana tabacum L.) plant growth, physiological function and response of key genes. Exposure to both BDE47 and BDE209 inhibited the growth of tobacco plants. The number of down-regulated DEGs following exposure to BDE47 was significantly higher than that following exposure to BDE209. Enrichment analysis using the KEGG showed that BDE47 and BDE209 primarily affected tobacco leaf photosynthesis-antenna proteins, photosynthesis, plant hormone signal transduction and α-linolenic acid metabolism. BDE47 primarily inhibits the synthesis of Chl a, and BDE209 has a more significant impact on Chl b. Most photosynthesis-related DEGs were concentrated in PSII and PSI; the number of down-regulated DEGs in PSI was significantly higher than that in PSII, and the range in which the PSI activity was reduced was also higher than that of PSII, i.e., PSII and PSI (particularly PSI) were sensitive to the effects of exposure to BDE47 and BDE209 on photosynthesis. The increase of the ratio of regulatory energy dissipation played an important protective role in alleviating the photoinhibition of PSII. Exposure to BDE47 and BDE209 can lead to the accumulation of ROS in tobacco leaves, but correspondingly, the activities of antioxidant enzymes SOD, POD, CAT, APX and GPX and the up-regulated expression of their coding genes play an important role in preventing excessive oxidative damage. Exposure to BDE47 and BDE209 promoted the up-regulation of gene expression related to Pro synthesis. In particular, the Pro synthetic process of the Orn pathway was promoted. Exposure to BDE47 and BDE209 induced the up-regulated expression of genes related to the synthesis of ABA and JA, promoted the synthesis of ABA and JA, and activated ABA and JA signal transduction pathways. In conclusion, both BDE47 and BDE209 inhibit the synthesis of chlorophyll and hinder the process of light energy capture and electron transfer in tobacco leaves. BDE47 was more toxic than BDE209. However, tobacco leaves can also adapt to BDE47 and BDE209 by regulating the antioxidant system, accumulating Pro and initiating the hormone signal transduction process. The results of this study provide a theoretical basis for the phytotoxicity mechanism of PBDEs. [Display omitted] • PBDEs disturb the photosynthetic electron transfer and cause peroxidative damage. • Tobacco leaves adapts to PBDEs by regulating the antioxidant system and accumulating proline. • Initiating hormone signal transduction is an important mechanism to adapt to PBDEs. • The toxicity of BDE47 to tobacco plants was higher than that of BDE209. [ABSTRACT FROM AUTHOR]

Plant 2-cysteine peroxiredoxin (2-Cys Prx) is a mercaptan peroxidase localized in chloroplasts and has unique catalytic properties. To explore the salt stress tolerance mechanisms of 2-Cys Prx in plants, we analyzed the effects of overexpressing the 2-Cys Prx gene on the physiological and biochemical metabolic processes of tobacco under NaHCO 3 stress through joint physiological and transcriptomic analysis. These parameters included growth phenotype, chlorophyll, photosynthesis, and antioxidant system. After NaHCO 3 stress treatment, a total of 5360 differentially expressed genes (DEGs) were identified in 2-Cys prx overexpressed (OE) plants, and the number of DEGs was significantly lower than 14558 in wild-type (WT) plants. KEGG enrichment analysis showed that DEGs were mainly enriched in photosynthetic pathways, photosynthetic antenna proteins, and porphyrin and chlorophyll metabolism. Overexpressing 2-Cys Prx significantly reduced the growth inhibition of tobacco induced by NaHCO 3 stress, alleviating the down-regulation of the DEGs related to chlorophyll synthesis, photosynthetic electron transport and the Calvin cycle and the up-regulation of those related to chlorophyll degradation. In addition, it also interacted with other redox systems such as thioredoxins (Trxs) and the NADPH-dependent Trx reductase C (NTRC), and mediated the positive regulation of the activities of antioxidant enzymes such as peroxidase (POD) and catalase (CAT) and the expression of related genes, thereby reducing the accumulation of superoxide anion (O 2· -), hydrogen peroxide (H 2 O 2) and malondialdehyde (MDA). In conclusion, 2-Cys Prx overexpression could alleviate the NaHCO 3 stress-induced photoinhibition and oxidative damage by regulating chlorophyll metabolism, promoting photosynthesis and participating in the regulation of antioxidant enzymes, and thus improve the ability of plants to resist salt stress damage. • ROS burst induced by NaHCO 3 stress damages the growth and photosystem of tobacco. • Overexpression of 2-Cys Prx alleviates photoinhibition and ROS accumulation. • 2-Cys Prx positively regulates photosynthesis and antioxidant-related genes. • 2-Cys Prx may cooperate with antioxidant systems such as NTRC under stress. [ABSTRACT FROM AUTHOR]