Nicotiana Tabacum Research Articles

EjWRKY6 Is Involved in the ABA-Induced Carotenoid Biosynthesis in Loquat Fruit during Ripening.

The yellow-fleshed loquat is abundant in carotenoids, which determine the fruit's color, provide vitamin A, and offer anti-inflammatory and anti-cancer health benefits. In this research, the impact of abscisic acid (ABA), a plant hormone, on carotenoid metabolism and flesh pigmentation in ripening loquat fruits was determined. Results revealed that ABA treatment enhanced the overall content of carotenoids in loquat fruit, including major components like β-cryptoxanthin, lutein, and β-carotene, linked to the upregulation of most genes in the carotenoid biosynthesis pathway. Furthermore, a transcription factor, EjWRKY6, whose expression was induced by ABA, was identified and was thought to play a role in ABA-induced carotenoid acceleration. Transient overexpression of EjWRKY6 in Nicotiana benthamiana and stable genetic transformation in Nicotiana tabacum with EjWRKY6 indicated that both carotenoid production and genes related to carotenoid biosynthesis could be upregulated in transgenic plants. A dual-luciferase assay proposed a probable transcriptional control between EjWRKY6 and promoters of genes associated with carotenoid production. To sum up, pre-harvest ABA application could lead to carotenoid biosynthesis in loquat fruit through the EjWRKY6-induced carotenoid biosynthesis pathway.

Evaluating the Forensic Inferences of Oral Nicotine Ingestion: Autopsy Case Review, Animal Experimentation, and Legal Implications

Nicotine, a highly lipophilic alkaloid derived from Nicotiana tabacum and Nicotiana rustica, can be lethal even in small doses when ingested in concentrated forms like e-cigarette liquids. This study examined a murder case in South Korea where a 52-year-old man was allegedly killed by oral administration of nicotine. Despite the absence of typical signs, such as chemical burns or vomiting, the case posed questions about the lethal concentration of nicotine and the presence of gastrointestinal symptoms in nicotine poisoning. Through literature review, autopsy analysis, and animal experiments, this study evaluated the forensic evidence presented in court. The results indicated that lethal nicotine levels could be lower than established previously, and death could occur without gastrointestinal injury or vomiting. Our findings supported the court's conviction decision, emphasizing the variability of symptoms in nicotine toxicity and the importance of scientific evidence in legal proceedings. The results of this study highlight the role of forensic medicine in clarifying scientific uncertainties in judicial contexts, particularly in cases involving toxic substances.

Overexpressing a cotton terpene synthase for (E)-β-ocimene biosynthesis in Nicotiana tabacum to recruit the parasitoid wasps

(E)-β-ocimene is a predominant component of volatile terpenes emitted from many plant species in response to herbivore attack, which plays an impotant role in direct and indirect defense of plants. In the current study, (E)-β-ocimene was induced and released in upland cotton Gossypium hirsutum plants infested by chewing caterpillars or sucking bugs. Using genome data mining, a key terpene synthase for (E)-β-ocimene biosynthesis in cotton, GhTPS16, was initially identified. In vitro, recombinant GhTPS16 catalyzed the formation of (E)-β-ocimene using geranyl diphosphate as a substrate. Besides, the GhTPS16 was transferred into Nicotiana tabacum to generate (E)-β-ocimene synthase overexpression lines. Consequently, compared with wild type plants both GhTPS16 expression and (E)-β-ocimene emission of transgenic plants were up-regulated. In behavioral trials, two parasitoid wasps, Peristenus spretus parasitizing green bug Apolygus lucorum and Microplitis mediator parasitizing cotton bollworm Helicoverpa armigera, showed tendency preference for synthetic (E)-β-ocimene and transgenic tobacco plants, respectively. These findings provide new insights into understanding the roles of (E)-β-ocimene in plant-insect interaction. Oversynthesis of (E)-β-ocimene in plants could enhance indirect defense by recruiting parasitoids to facilitate control of the two target pests, green bug and cotton bollworm.

Biochar modulates the antioxidant system and hormonal signaling in tobacco under continuous-cropping conditions

ABSTRACT As an important economic crop, tobacco faces the common challenges of continuous cropping due to the limited amount of arable land. Biochar has certain preventive and control effects on continuous cropping obstacles and can improve crop yield and quality. This study aims to explore the regulation of the antioxidant system and hormone signaling in tobacco under continuous cropping conditions by biochar. We studied the impact of biochar (Nicotiana tabacum LJ911 and LY101) on plant physiological functions and transcriptomes of tobacco under continuous cropping conditions. The results showed that biochar regulates photosynthetic gas exchange parameters in both tobacco varieties. Biochar significantly increased the activity of antioxidant enzymes in the leaves of both tobacco varieties under continuous-cropping conditions. Additionally, biochar up-regulated endogenous abscisic acid, auxin, and jasmonic acid in the leaves of both tobacco varieties, with higher levels observed in LY101 than in LJ911. Through Weighted Gene Co-expression Network Analysis (WGCNA), it was found that the tobacco antioxidant system and hormones showed a significant response. Biochar improved photosynthetic efficiency, enhanced antioxidant capacity, and promoted tobacco growth through hormone synthesis and signaling. In summary, biochar application can serve as a promising strategy to mitigate the challenges associated with continuous cropping in tobacco cultivation.

A novel mutation in non-constitutive lycopene beta cyclase (CstLcyB2a) from Crocus sativus modulates carotenoid/apocarotenoid content, biomass and stress tolerance in plants.

Mutation at A126 in lycopene-β-cyclase of Crocus (CstLcyB2a) sterically hinders its binding of δ-carotene without affecting lycopene binding, thereby diverting metabolic flux towards β-carotene and apocarotenoid biosynthesis. Crocus sativus, commonly known as saffron, has emerged as an important crop for research because of its ability to synthesize unique apocarotenoids such as crocin, picrocrocin and safranal. Metabolic engineering of the carotenoid pathway can prove a beneficial strategy for enhancing the quality of saffron and making it resilient to changing climatic conditions. Here, we demonstrate that introducing a novel mutation at A126 in stigma-specific lycopene-β-cyclase of Crocus (CstLcyB2a) sterically hinders its binding of δ-carotene, but does not affect lycopene binding, thereby diverting metabolic flux towards β-carotene formation. Thus, A126L-CstLcyB2a expression in lycopene-accumulating bacterial strains resulted in enhanced production of β-carotene. Transient expression of A126L-CstLcyB2a in C. sativus stigmas enhanced biosynthesis of crocin. Its stable expression in Nicotiana tabacum enhanced β-branch carotenoids and phyto-hormones such as abscisic acid (ABA) and gibberellic acids (GA's). N. tabacum transgenic lines showed better growth performance and photosynthetic parameters including maximum quantum efficiency (Fv/Fm) and light-saturated capacity of linear electron transport. Exogenous application of hormones and their inhibitors demonstrated that a higher ratio of GA4/ABA has positive effects on biomass of wild-type and transgenic plants. Thus, these findings provide a platform for the development of new-generation crops with improved productivity, quality and stress tolerance.

Efficacy of Ascorbic Acid on Anti-Infertility Effects of Alcoholic Extract of Nicotiana Tabacum Leaf in Male Wistar Rat

Background: Tobacco intake has led to negative impacts on the neurological and endocrine systems, possibly due to the compromised immune system that is linked to tobacco use. Despite the long history of using the tobacco plant (Nicotiana tabacum L.), cigarettes dominate the global market, making up 96% of all sales of manufactured tobacco products. Despite being taken in smokeless form, reports indicate that the plant is toxic and has negatively affected several bodily cellular activities. This study looked at how an alcoholic extract made from Nicotiana tabacum leaf affected the Wistar male rats' reproductive parameters. According to estimates from the World Health Organization, tobacco usage resulted in 100 million deaths worldwide throughout the 20th century, and 5.4 million fatalities in 2004. Except for humans, non-human primates, and guinea pigs, the livers of most mammalian species synthesis vitamin C, also known as ascorbic acid, a six- carbon lactone molecule. Scurvy, also known as scorbutus, is a life-threatening disorder caused by a shortage of vitamin C. It can only be cured via proper treatment. Therefore, humans must consume vitamin C to ensure their survival. The testis is the primary male reproductive organ. The structure is analogous to the ovaries in females. The testes are the main endocrine and reproductive organs in the male body. They generate sex steroid hormones and mature haploid sperm. The testes are located in two pairs within the scrotum, with the epididymis situated at the back edge.  Material and Method: The extract was obtained from the plant's leaf using the process of alcoholic extraction. The experiment utilized a sample of 30 male Wistar rats, which were assigned randomly to five groups: A, B, C, D, and E. Each group consisted of six rats with an average weight of 115g.  Result: Changes in body weight, testis weight, semen quality, and morphology were all studied in this investigation. Furthermore, testicular histology evaluations were carried out. Overall, the alcoholic extract derived from the leaf of Nicotiana tabacum had a significant negative impact on various male reproductive indices. This study demonstrates that ascorbic acid possesses prospective and restorative effects against testicular damage caused by the alcoholic extract of Nicotiana tabacum leaf. However, it should be noted that these effects were not fully observed at the current dosage. Further investigation is necessary to fully understand the long-lasting effects on reproductive health.

Evaluating the impact of alyssum flower strips on biological control of key pests in flue‐cured tobacco agroecosystems

AbstractFlue‐cured tobacco, Nicotiana tabacum (L.), is often attacked by various pests such as aphids, whiteflies and tobacco budworm. Insecticide application has been the primary method in managing these pests for Yunnan Province. However, it is necessary to look for more sustainable strategies that can help control pests. In this context, conservation biological control is a highly promising alternative, involving the cultivation or conservation of flowering plants within the agricultural ecosystem to attract and support natural enemies. The objective of this study was to evaluate the potential of alyssum, Lobularia maritima (L.) Desv., in attracting natural enemies and managing pests in flue‐cured tobacco cultivation. The study conducted two field experiments over successive years, each with of two treatments and three replicates, arranged in a completely randomized design. The treatments were (1) tobacco monoculture and (2) tobacco intercropped with alyssum flower strips. The population density of natural enemies and pests was monitored weekly throughout the study period. The results showed that the presence of alyssum flowers in the tobaccosalyssum treatment significantly increased the abundance of generalist predators such as syrphids, rove beetles, carabids, Orius sp. and spiders during both experiments. This increase in predator population led to a substantial reduction in tobacco pests, particularly aphids. Intercropping alyssum with tobacco can serve as an effective strategy for managing pests specific to the Nicotiana plant, as well as addressing the limited availability of approved insecticides for this crop. This approach may help to mitigate pest‐related issues and reduce the reliance on insecticides in tobacco cultivation, contributing to more sustainable pest management practices.

Crop Management System Consisting of Biodegradable Mulching Film + Drip Irrigation Increases Yield and Quality of Flue-Cured Tobacco

Mulching is one of the most recommended practices in agriculture due to its positive effects on the plant/soil system. Very few experiments have been conducted to date to investigate the effect of mulching, with both organic and inorganic materials, on tobacco. The main aim of this study was to test the synergic effect of a soil-biodegradable (according to standard EN17033) mulching film (the commercial Mater-Bi®, Novamont SpA, Novara, Italy) and drip irrigation (M-D) compared with that of bare soil and sprinkler/drip irrigation (first/second part of the growing season; BS-SD) on a tobacco crop (Nicotiana tabacum L., flue-cured Virginia) grown in the Tiber Valley (the tobacco cultivation district of Central Italy). BS-SD represents the standard practice applied by tobacco growers in the study area. The plants grown under the M-D management system grew more and developed faster than the plants grown under BS-SD conditions. Under the M-D system, yields increased in comparison with the BS-SD conditions (+29%, on average). The gross revenue obtained via the M-D-cured products also increased (+63%, on average) thanks to higher prices assigned by expert evaluators on the basis of the extrinsic quality traits (color, structure and texture, degree of ripeness, elasticity, lamina integrity, handling defects, and vein incidence). The economic value of the cured products increased with the leaf crowns; it was the lowest in the basal (B) leaves and the highest in the middle-upper (MU) leaves. The intrinsic quality traits of the cured leaves (total N and nitrate contents, alkaloids, and reducing sugars) also confirmed that the best quality was found in the M-D-cured products, as determined by expert evaluation. Interestingly, the reducing sugar (RS) contents of tobacco obtained using the M-D management system were 2.5-, 1.1-, and 0.9-fold greater than those under the BS-SD conditions (B, M, and MU products, respectively). An additional commercial value of the cured products was thus obtained with the M-D crop management system due to RS, an intrinsic quality trait considered by manufacturing industries.

Establishing a High-Yield Chloroplast Cell-Free System for Prototyping Genetic Parts.

Plastid engineering offers the potential to carry multigene traits in plants; however, it requires reliable genetic parts to balance expression. The difficulty of chloroplast transformation and slow plant growth makes it challenging to build plants just to characterize genetic parts. To address these limitations, we developed a high-yield cell-free system from Nicotiana tabacum chloroplast extracts for prototyping genetic parts. Our cell-free system uses combined transcription and translation driven by T7 RNA polymerase and works with plasmid or linear template DNA. To develop our system, we optimized lysis, extract preparation procedures (e.g., runoff reaction, centrifugation, and dialysis), and the physiochemical reaction conditions. Our cell-free system can synthesize 34 ± 1 μg/mL luciferase in batch reactions and 60 ± 4 μg/mL in semicontinuous reactions. We apply our batch reaction system to test a library of 103 ribosome binding site (RBS) variants and rank them based on cell-free gene expression. We observe a 1300-fold dynamic range of luciferase expression when normalized by maximum mRNA expression, as assessed by the malachite green aptamer. We also find that the observed normalized gene expression in chloroplast extracts and the predictions made by the RBS Calculator are correlated. We anticipate that chloroplast cell-free systems will increase the speed and reliability of building genetic systems in plant chloroplasts for diverse applications.

A P450 superfamily member NtCYP82C4 promotes nicotine biosynthesis in Nicotiana tabacum

In plants, cytochrome P450s are monooxygenase that play key roles in the synthesis and degradation of intracellular substances. In tobacco, the majority of studies examining the P450 superfamily have concentrated on the CYP82E subfamily, where multiple family members function as demethylases, facilitating the synthesis of nornicotine. In this study, NtCYP82C4, a tobacco P450 superfamily member, was identified from a gene-edited tobacco mutant that nicotine biosynthesis in tobacco leaves is evidently reduced. Compared to the wild-type plants, the knockout of NtCYP82C4 resulted in a significantly lower nicotine content and biomass in tobacco leaves. Transcriptome and metabolome analyses indicated that the knockout of NtCYP82C4 inhibites secondary metabolic processes in tobacco plants, leading to the accumulation of some important precursors in the nicotine synthesis process, including aspartic acid and nicotinic acid, and increases nitrogen partitioning associated with those processes such as amino acid synthesis and utilization. It is speculated that NtCYP82C4 may function as an important catalase downstream of the nicotine synthesis. Currently, most of the steps and enzymes involved in the nicotine biosynthesis process in tobacco have been elucidated. Here, our study deepens the current understanding of nicotine biosynthesis process and provides new enzyme targets for nicotine synthesis in tobacco plants.

Catecholamine levels with use of electronic and combustible cigarettes.

Smoking elevates catecholamines that increase the risk for cardiovascular disease. Sparse evidence exists about the effects of e-cigarettes and catecholamines. Higher levels of catecholamines could trigger the increased heart rate, blood pressure, and decreased vascular function reported with the use of e-cigarettes. We investigated the difference in urinary catecholamines and their metabolites before and after the use of an e-cigarette containing nicotine or cigarettes compared to no tobacco use. In our observational cohort exposure study, healthy adults aged 21-45 years who were currently using e-cigarettes, cigarettes, or had never used tobacco, participated in an acute exposure visit using their most common tobacco product. Urine was collected before, 1, and 2 hours after a 3-second puff every 30 seconds for 10 minutes on an e-cigarette or straw or use of 1 cigarette. Urinary catecholamines and their metabolites were measured by ultra-high-performance liquid chromatography. Participants (n=323) were grouped by the product used at the visit. We compared levels of creatinine normalized log-transformed urinary catecholamines and their metabolites across groups using Dunn's test following a Kruskal-Wallis test in unadjusted and demographically adjusted models. Prior to use, individuals who used cigarettes (n=70) had lower urinary metabolites from epinephrine, serotonin, and norepinephrine. No differences were seen in those who used e-cigarettes (n=171) and those who did not use tobacco (n=82). In fully adjusted models, 1 h after the use of a combustible or e-cigarette, log-transformed urinary metabolites from norepinephrine (β=1.22; 95% CI: 0.39-2.05, p=0.004 and β=1.06; 95% CI: 0.39-1.74, p=0.002), dopamine (β=0.37; 95% CI: 0.24-0.5, p<0.001 and β=0.15; 95% CI: 0.05-0.26, p<0.001), and epinephrine (β=1.89; 95% CI: 0.51-3.27, p=0.008 and β=1.49; 95% CI: 0.38-2.61, p=0.009) were elevated. In fully adjusted models, combustible cigarette use was associated with elevated urinary norepinephrine (β=0.46; 95% CI: 0.13-0.81, p=0.007) and dopamine (β=0.19; 95% CI: 0.06-0.31, p=0.003) 1 h after use. We found that the use of both e-cigarettes and cigarettes was associated with elevated urinary catecholamines or their metabolites. Catecholamines could be useful as a biomarker of harm for tobacco use and considered by tobacco regulatory scientists in future research.

Effect of mutation of phaC on carbon supply, extracellular polysaccharide production, and pathogenicity of Xanthomonas oryzae pv. oryzae

Xanthomonas oryzae pv. oryzae (Xoo) causes bacterial blight in rice. Polyhydroxyalkanoates (PHAs) consitute a diverse group of biopolyesters synthesized by bacteria under nutrient-limited conditions. The phaC gene is important for PHA polymerization. We investigated the effects of phaC gene mutagensis in Xoo strain PXO99A. The phaC gene knock-out mutant exhibited reduced swarming ability relative to that of the wild-type. Under conditions where glucose was the sole sugar source, extracellular polysaccharide (EPS) production by ΔphaC declined by 44.8%. ΔphaC showed weak hypersensitive response (HR) induction in the leaves of non-host Nicotiana tabacum, concomitant with downregulation of hpa1 gene expression. When inoculated in rice leaves by the leaf-clipping method, ΔphaC displayed reduced virulence in terms of lesion length compared with the wild-type strain. The complemented strain showed no significant difference from the wild-type strain, suggesting that the deletion of phaC in Xoo induces significant alterations in various physiological and biological processes. These include bacterial swarming ability, EPS production, transcription of hrp genes, and glucose metabolism. These changes are intricately linked to the energy utilization and virulence of Xoo during plant infection. These findings revealed involvement of phaC in Xoo is in the maintaining carbon metabolism by functioning in the PHA metabolic pathway.

Efficacy of Fusarium caatingaense and botanical extracts in controlling Dactylopius opuntiae (Hemiptera: Dactylopiidae) in the field

In this study, we evaluated the effectiveness of Fusarium caatingaense URM 6778 and URM 6779 alone and combined with aqueous extracts of Ricinus communis 5% and Nicotiana tabacum 10% against Dactylopius opuntiae in the field. The effectiveness of the extracts alone was also evaluated. The botanical extracts were subjected to phytochemical screening to identify biologically active chemical compounds. Total mortality data were corrected using the Schneider-Orelli formula. The results were submitted for analysis of variance (ANOVA), and the means were compared using Tukey’s test at 5% probability. The phytochemical screening of R. communis and N. tabacum showed that both extracts contained alkaloids, flavonoid glycosides, saponins, and tannins. According to the confirmed mortality, URM 6779 (61.67%) and URM 6778 + aqueous extract of R. communis at 5% (43.89%) were the best treatments for the control of D. opuntiae in the field. The aqueous extracts of N. tabacum at 10% and R. communis at 5% resulted in mortality rates of 75.14% and 65.32%, respectively, and are also options for controlling this insect. Despite promising results, for the applicability of such agents to be safe, investigations into their toxicity to non-target organisms and their permanence in the environment are necessary.

Functional characterization of WsPR-1 reveals its interplay with cytokinin and gibberellin signaling pathways

Pathogenesis-related protein 1 (PR-1) is an antimicrobial protein involved in systemic acquired resistance (SAR) in plants, but its regulatory role and interactions with other pathways remain unclear. In this study, we functionally characterize WsPR-1 gene of Withania somnifera in Nicotiana tabacum to elucidate its role in plant defense, growth, and development. Interestingly, transgenic tobacco plants with increased levels of cytokinin (CK) and decreased gibberellins (GAs) exhibited stunted shoot growth, an underdeveloped root system, modified leaf morphology, reduced seed pod production, and delayed leaf senescence. Transcriptional analysis revealed that WsPR-1 overexpression downregulated the GA 20-oxidase (GA20ox) gene involved in GA biosynthesis while upregulating GA 2-oxidase (GA2ox), a GA catabolic enzyme. Moreover, transcript levels of FRUITFULL (FUL) and LEAFY (NFL2) flowering genes exhibited a decrease in WsPR-1 plants, which could explain the delayed flowering and reduced seed pod development in transgenic plants. Confocal microscopy confirmed increased lignin deposition in stem cross-sections of WsPR-1 transgenic plants, supported by gene expression analysis and lignin content quantification. Additionally, our findings also suggest the involvement of Knotted1-like homeobox (KNOX) gene in enhancing cytokinin levels. This study highlights PR-1's regulatory role in plant growth and development, with potential to boost crop yields and enhance resilience.

Function of the NAC1 Gene from Fraxinus mandshurica in Cold Resistance and Growth Promotion in Tobacco

To elucidate the function of the cold-resistance regulatory gene FmNAC1 from Fraxinus mandshurica Rupr., this study identified the role that overexpression of the FmNAC1 gene plays in tobacco growth and cold-stress regulation. The cloned FmNAC1 gene from F. mandshurica is 891 bp in length and encodes 296 amino acids. Our subcellular localization analysis confirmed that FmNAC1 is primarily located in the nucleus and functions as a transcription factor. FmNAC1 is responsive to cold and NaCl stress, as well as to the induction of IAA, GA, and ABA hormone signals. To further elucidate its function in cold resistance, four transgenic tobacco lines expressing FmNAC1 (FmNAC1-OE) were generated through tissue culture after the Agrobacterium-mediated transformation of wild-type (WT) Nicotiana tabacum L.. These FmNAC1-OE plants exhibited accelerated growth after transplantation. When exposed to low-temperature conditions at −5 °C for 24 h, the rates of wilting and yellowing of the FmNAC1-OE plants were significantly lower than those of the WT tobacco plants. Additionally, the membrane integrity, osmotic regulation, and reactive oxygen species (ROS)-scavenging abilities of the FmNAC1-OE tobacco lines were better than those of the WT plants, indicating the potential of the FmNAC1 gene to improve plant cold resistance. The gene expression results further revealed that the FmNAC1 transcription factor exhibits regulatory interactions with growth-related genes such as IAA and AUX1; cold-resistance-related genes such as ICE, DREB, and CBF1; and genes involved in the clearance of reactive oxygen species (ROS), such as CAT and SOD. All of this evidence shows that the FmNAC1 transcription factor from F. mandshurica plays a key role in contributing to the enhancement of growth, cold resistance, and ROS clearance in transgenic tobacco plants.

Genome-wide analysis of Citrus medica ABC transporters reveals the regulation of fruit development by CmABCB19 and CmABCC10

ATP-binding cassette (ABC) transporters are vital for plant growth and development as they facilitate the transport of essential molecules. Despite the family's significance, limited information exists about its functional distinctions in Citrus medica. Our study identified 119 genes encoding ABC transporter proteins in the C. medica genome. Through an evolutionary tree and qPCR analysis, two ABC genes, CmABCB19 and CmABCC10, were implicated in C. medica fruit development, showing upregulation in normal fruits compared to malformed fruits. CmABCB19 was found to localize to the plasma membrane of Nicotiana tabacum, exhibiting indole-3-acetic acid (IAA) efflux activity in the yeast mutant strain yap1. CmABCC10, a tonoplast-localized transporter, exhibited efflux of diosmin, nobiletin, and naringin, with rutin influx in strain ycf1. Transgenic expression of CmABCB19 and CmABCC10 in Arabidopsis thaliana induced alterations in auxin and flavonoid content, impacting silique and seed size. This effect was attributed to the modulation of structural genes in the auxin biosynthesis (YUC5/9, CYP79B2, CYP83B1, SUR1) and flavonoid biosynthesis (4CL2/3, CHS, CHI, FLS1/3) pathways. In summary, the functional characterization of CmABCB19 and CmABCC10 illuminates auxin and flavonoid transport, offering insights into their interplay with biosynthetic pathways and providing a foundation for understanding the transporter's role in fruit development.

Effect of 25% Tobacco Leaf Extract (Nicotiana Tabacum L.) as a Denture Cleaning Paste on Surface Roughness and Color Change Thermoplastic Nylon

Thermoplastic nylon as a denture base requires mechanical cleaning with denture paste. Previous research showed that tobacco leaf extract paste (TLEP) 25% was fungistatic on thermoplastic nylon denture bases. The aim is to evaluate the roughness and colour changes of thermoplastic nylon against tobacco leaf extract paste 25% during one year of simulated use. This research hypothesizes that thermoplastic nylon's roughness and colour value will decrease further after brushing using 25% TLEP. Sample groups include brushing without paste, paste without TLEP 25% and TLEP 25%. The sample size for each group was 15 samples; measurements use a surface roughness tester and a colour reader. Brushing was carried out for 23.5 minutes on a plate measuring 60x10x2.5 mm as a surface roughness test and 3.90 minutes on a plate measuring 10x10x2.5 mm as a colour change test. The sample size for each group was 15 samples; measurements use a surface roughness tester and a colour reader. The research results were tested using Kolmogorov-Smirnov and Levene and One-way ANOVA with a significance level of 0.05. There were no differences in surface roughness and colour changes on thermoplastic nylon plates after brushing with 25% TLEP (p0.05). This study concluded that 25% TLEP did not affect increasing surface roughness and changing the colour of thermoplastic nylon plates with values below the threshold.

Characteristics of Corynespora cassiicola, the causal agent of tobacco Corynespora leaf spot, revealed by genomic and metabolic phenomic analysis

Corynespora cassiicola is a highly diverse fungal pathogen that commonly occurs in tropical, subtropical, and greenhouse environments worldwide. In this study, the isolates were identified as C. cassiicola, and the optimum growth and sporulation were studied. The phenotypic characteristics of C. cassiicola, concerning 950 different growth conditions, were tested using Biolog PM plates 1–10. In addition, the strain of C. cassiicola DWZ from tobacco hosts was sequenced for the using Illumina PE150 and Pacbio technologies. The host resistance of tobacco Yunyan 87 with different maturity levels was investigated. In addition, the resistance evaluation of 10 common tobacco varieties was investigated. The results showed that C. cassiicola metabolized 89.47% of the tested carbon source, 100% of the nitrogen source, 100% of the phosphorus source, and 97.14% of the sulfur source. It can adapt to a variety of different osmotic pressure and pH environments, and has good decarboxylase and deaminase activities. The optimum conditions for pathogen growth and sporulation were 25–30 °C, and the growth was better on AEA and OA medium. The total length of the genome was 45.9 Mbp, the GC content was 51.23%, and a total of 13,061 protein-coding genes, 202 non-coding RNAs and 2801 and repeat sequences were predicted. Mature leaves were more susceptible than proper mature and immature leaves, and the average diameter of diseased spots reached 17.74 mm at 12 days. None of the tested ten cultivars exhibited obvious resistance to Corynespora leaf spot of tobacco, whereby all disease spot diameters reached > 10 mm and > 30 mm when at 5 and 10 days after inoculation, respectively. The phenotypic characteristics, genomic analysis of C. cassiicola and the cultivar resistance assessment of this pathogen have increased our understanding of Corynespora leaf spot of tobacco.

Integrating Transcriptome and Metabolome Analysis Unveils the Browning Mechanism of Leaf Response to High Temperature Stress in Nicotiana tabacum

During the process of flue-curing and processing, leaves from cash crops such as tea and tobacco frequently undergo a phenomenon of browning, leading to reduced quality and significant economic losses. Despite a variety of approaches developed to suppress browning, little is known about the role that flue-curing of postharvest leaves with stems plays in delaying browning. This study investigated the impact of leaf-with-stem (LWS) flue-curing on the browning of tobacco and its underlying mechanisms. Physiological results indicated that LWS flue-curing effectively delayed browning by enhancing antioxidant capacity and maintaining reactive oxygen species (ROS) levels during the yellowing stage. Comprehensive transcriptome and metabolome analyses showed that LWS flue-curing significantly influenced various metabolic pathways. Specifically, 196, 218, and 402 metabolites, and 65, 131, and 718 genes exhibited significant changes at the 38 °C, 40 °C, and 42 °C stages, respectively, inhibiting membrane lipid degradation and enhancing the supply of reducing hydrogen through the oxidative pentose-phosphate pathway. Additionally, hormone signaling pathways were found to be associated with LWS flue-curing. These findings highlight the complex interplay of metabolic pathways and signaling networks in attenuating browning, providing valuable insights for minimizing postharvest leaf browning during flue-curing and processing.

Influence of Weather Conditions and the Aphid Population on the Potato Virus Y Infection of Tobacco in the Field

Potato virus Y (PVY) is a major tobacco (Nicotiana tabacum L.) pathogen that causes severe crop losses. We studied the influence of meteorological factors and a population of twelve aphid species on the development of PVY in field-grown tobacco from 1996 to 2010 in Poland. Three PVY-susceptible tobacco varieties were used in the study. The mean virus incidence ranged from 18% in 2010 to almost 99% in 1996, 2004, and 2009. For determining the relationship between tobacco plant infection and meteorological conditions and aphid populations, logistic regression analysis was used. It was found that the probability of PVY infection is significantly dependent on the average air temperature, relative humidity, number of days with an average temperature of at least 25 °C, and the abundance of Aphis fabae and Brachycaudus helichrysi. The probability of infection of tobacco plants with potato virus Y decreased with increasing air temperature and relative humidity. In addition, with each subsequent day with a temperature of at least 25 °C, the risk of infection decreased by 24%. Furthermore, it was often observed that high populations of Aphis fabae and Brachycaudus helichrysi were associated with a high incidence of virus infection in tobacco plants.