Development of a stable attenuated double-mutant of tobacco mosaic virus for cross-protection

Tobacco(Nicotiana tabacum)and tomato(Solanum lycopersicum)are two major economic crops in China.Tobacco mosaic virus(TMV;genus Tobamovirus)is the most prevalent virus infecting both crops.Currently,some widely cultivated tobacco and tomato cultivars are susceptible to TMV and there is no effective strategy to control this virus.Cross-protection can be a safe and environmentally friendly strategy to prevent viral diseases.However,stable attenuated TMV mutants are scarce.In this study,we found that the substitutions in the replicase p126,arginine at position 196(R^(196))with aspartic acid(D),glutamic acid at position 614(E^(614))with glycine(G),serine at position 643(S^(643))with phenylalanine(F),or D at position 730(D^(730))with S,significantly reduced the virulence and replication of TMV.However,only the mutation of S^(643) to F reduced the RNA silencing suppression activity of TMV p126.A double-mutant TMV-E614G-S643F induced no visible symptom and was genetically stable through six successive passages in tobacco plants.Furthermore,our results showed that TMV-E614G-S643F double-mutant could provide effective protection against the wild-type TMV infection in tobacco and tomato plants.This study reports a promising mild mutant for cross-protection to control TMV in tobacco and tomato plants.

Comparison of Combustion Characteristics of Tars Produced with Tobacco Stem Biomass Gasification

In order to study the combustion characteristics of tar in biomass gasifier inner wall and gasification gas,“tobacco stem semi-tar inside furnace”,“tobacco stem tar inside furnace”and“tobacco stem tar out-of-furnace”were subjected to thermogravimetric experiments,and the combustion characteristics and kinetic characteristics were analyzed.The result shows that“tobacco stem semi-tar inside furnace”has the highest value and“tobacco stem tar out-of-furnace”is has the lowest value on ignition characteristics,combustion characteristics and combustible stability;“tobacco stem semi-tar inside furnace”has the lowest value and“tobacco stem tar outside furnace”has the highest value on burnout characteristics;“tobacco stem tar outside furnace”has the highest value and“tobacco stem tar inside furnace”has the lowest value on integrated combustion characteristics.

Plant Chemical Defenses against Insect Herbivores—Using theWild Tobacco as a Model

The Nicotiana genus, commonly known as tobacco, holds significant importance as a crucial economic crop. Confrontedwith an abundance of herbivorous insects that pose a substantial threat to yield, tobacco has developed adiverse and sophisticated array of mechanisms, establishing itself as a model of plant ecological defense. Thisreview provides a concise overview of the current understanding of tobacco’s defense strategies against herbivores.Direct defenses, exemplified by its well-known tactic of secreting the alkaloid nicotine, serve as a potent toxinagainst a broad spectrum of herbivorous pests. Moreover, in response to herbivore attacks, tobacco enhancesthe discharge of volatile compounds, harnessing an indirect strategy that attracts the predators of the herbivores.The delicate balance between defense and growth leads to the initiation of most defense strategies only after aherbivore attack. Among plant hormones, notably jasmonic acid (JA), play central roles in coordinating thesedefense processes. JA signaling interacts with other plant hormone signaling pathways to facilitate the extensivetranscriptional and metabolic adjustments in plants following herbivore assault. By shedding light on these ecologicaldefense strategies, this review emphasizes not only tobacco’s remarkable adaptability in its natural habitatbut also offers insights beneficial for enhancing the resilience of current crops.

Variations of phyllosphere microorganisms in asymptomatic and tobacco brown spot leaves before and after spraying 12% difenoconazole + fluxapyroxad SC

12%difenoconazole+fluxapyroxad SC(commercial name:Jiangong)was first released by BASF in China in 2016.It has been registered to control many diseases,including pear scab,apple Alternaria leaf spot,tomato early blight,cucumber powdery mildew,etc.This study evaluated the bioactivity of Jiangong against Alternaria alternata and explored variations of phyllosphere microorganisms in both asymptomatic and tobacco brown spot leaves at different persistence periods(0,5,10,and 15 days post-fungicide application)using high-throughput sequencing technology.The results indicated that Jiangong effectively inhibited mycelial growth(average EC_(50) value of 0.51μg/mL),conidia germination(average EC_(50) value of 3.47μg/mL),and the carbon metabolism of A.alternata.Both asymptomatic and symptomatic leaves presented complex microbial communities.Higher fungal diversity was noted in asymptomatic leaves,while higher bacterial diversity was found in symptomatic leaves.After application,the diversity and abundance of microbial community structures in both types of leaves changed over time.Fungal microbiome communities showed greater sensitivity than bacterial groups,with the microbiome communities of asymptomatic leaves being more affected than those of symptomatic leaves.Fungal community diversity decreased for both symptomatic and asymptomatic leaves after 5 days of application,while the diversity of fungal community in symptomatic leaves showed an upward trend after 10 days of application.Meanwhile,bacterial community diversity increased in both symptomatic and asymptomatic leaves after 5 days of application but then declined in asymptomatic leaves after 15 days.The abundance of the dominant function group of phyllosphere bacteria(metabolism,genetic information processing,environmental information processing)was not affected by the application of Jiangong.However,the abundance of the dominant function group of phyllosphere fungi(animal pathogen-endophyte-wood saprotroph,endophyte-plant pathogen,plant pathogen-undefined saprotroph)was significantly affected by the application of Jiangong,and high variation was found in symptomatic leaves than that of asymptomatic leaves.The application of Jiangong-induced alterations in the community structure of the tobacco phyllosphere microbiome provides a basis for future tobacco brown spot control strategies based on phyllospheric microecology.

Smokeless Tobacco Use among Women in Kasama District-Zambia

Background: Smokeless tobacco is defined as a product that contains tobacco, is not smoked or burned at the time of use, and commonly consumed orally or nasally. These products can be placed in the mouth, cheek or the lip and are sucked or chewed. The Zambian government, in the 2019 country report, gave an estimated figure of 4.5% of females aged 15 years and above in 2017 used smokeless tobacco and by 31st December, 2018, there was an increase of smokeless tobacco users to 6.8% women of the same age group. This study aimed to explore the extent of smokeless tobacco use among women in Kasama district-Zambia. Methodology: An analytical cross-sectional quantitative study design was used to collect data using the modified structured interview schedule, adopted from Medicine for Global Health. Simple random sampling method using rotary technique was used to select 430 respondents after meeting the inclusion criteria. Informed consent to participate in the study was obtained. Data was analysed using version 26.0 of the Statistical Package for Social Sciences. Appropriate parametric or non-parametric statistical tests (Chi-squared or Fisher’s exact test) were adopted in testing for associations between variables. Univariable and multivariable binary logistic regression analysis were employed in identifying smokeless tobacco use among women using an investigator-led stepwise approach, guided by various fit statistics and the likelihood ratio test. All statistical analyses adopted a 5% significance level at 95% confidence interval. Results: The results showed that most of the respondents were aged between 18 and 25 years (45.6%), (53.7%) lived in urban settlements and the majority (80%) were unemployed. The majority of respondents (83.5%) had a friend/relative who used smokeless tobacco and over half (53.5%) thought smokeless tobacco was beneficial to them. The commonly mentioned benefits of smokeless tobacco included body warmth (13.6%) and vaginal tightening (7.9%). The results revealed that most of the respondents attained a secondary level of education (38.4%). According to the study, smokeless tobacco use among women of Kasama-Zambia was significantly associated with the following;age (p Conclusion: Based on these findings, the study recommends that efforts should be channeled towards the dissemination of information on the impacts of smokeless tobacco use in order to overcome cultural beliefs attached to smokeless tobacco use.

Determinants of Tobacco Cultivation and the Associated Impacts of Adoption in Hurungwe District, Zimbabwe

Tobacco is an essential cash crop in Zimbabwe and a strategic livelihood option for hundreds of thousands of rural households. However, the crop is linked to negative environmental, economic, and social impacts. The existing studies on tobacco cultivation in Zimbabwe present contradictory findings on the determinants and impacts of adoption, leaving unanswered questions about the crop’s sustainability impact in the country. This article investigates the determinants of smallholder farmers’ decisions to grow tobacco and the associated impacts of adoption. Random and purposive sampling were used to select 273 household surveys, including tobacco and non-tobacco smallholder farmers, and 56 expert interviews to answer the research questions. We employed regression models alongside expert interviews and document analysis to identify the determinants influencing the decision-making process of smallholder farmers in Zimbabwe regarding tobacco cultivation. Additionally, our investigation aimed to elucidate the perceived impacts associated with the adoption of this agricultural practice. The regression analysis indicated that the farmer’s age, education level, farming experience, family size, household income, and perceived high farm profitability are significant drivers of tobacco adoption. We also discovered divergent and convergent perceptions of the critical impacts of tobacco cultivation. The study highlights the need for proactive multi-stakeholder collaboration and sustainable financial arrangements to address the negative impacts of tobacco production. As the primary stakeholder responsible for regulating and promoting agricultural activities, the Zimbabwean government should provide meaningful financial support, increase access to credit, and ensure better market facilities for alternative crops to reduce the over-dependence on tobacco.

Field Prevention and Control of Tobacco Black Shank in Guizhou Province

[Objectives]The paper was to explore the prevention and therapeutic schedule of tobacco black shank.[Methods]Different concentrations of 25 g/L fludioxonil·37.5 g/L metalaxyl-M,10 billion/mL Bacillus amyloliquefaciens,110 g/L amino acids·24 g/L manganese zinc,120 g/L calcium·20 g/L magnesium,and 4%metalaxyl-M·64%mancozeb were employed to assess their efficacy in controlling tobacco black shank.The disease index was subsequently evaluated.[Results]25 g/L fludioxonil·37.5 g/L metalaxyl-M+10 billion/mL B.amyloliquefaciens+110 g/L amino acids·24 g/L manganese zinc(transplanting dosage)or 120 g/L calcium·20 g/L magnesium(sealing dosage)(transplanting dosage:750 mL/hm 2+1.2×104 mL/hm 2+1.5×103 mL/hm 2,sealing dosage:1.5×103 mL/hm 2+1.2×104 mL/hm 2+1.5×103 mL/hm 2)resulted in a notable impact on the prevention of tobacco black shank.The incidence in the treated area was 10.78%,a 35.72%reduction compared to the control.The estimated yield was 99700 yuan/hm 2,a 34.91%increase compared to the control.25 g/L fludioxonil·37.5 g/L metalaxyl-M+10 billion/mL B.amyloliquefaciens+120 g/L calcium·20 g/L magnesium+4%metalaxyl-M·64%mancozeb(control dosage:1.5×103 mL/hm 2+1.2×104 mL/hm 2+1.5×103 mL/hm 2+1.5×103 g/hm 2,1.5×103 mL/hm 2+1.2×104 mL/hm 2+1.5×103 mL/hm 2+1.5×103 g/hm 2,with an interval of 7 d between applications)demonstrated a significant efficacy in controlling tobacco black shank.At 7 d following the second application,the relative preventive efficacy was observed to be 88.99%.Additionally,the estimated yield was 109900 yuan/hm 2,representing an increase of 244.51%compared to the control.[Conclusions]During the transplanting and sealing stages,25 g/L fludioxonil·37.5 g/L metalaxyl-M+10 billion/mL B.amyloliquefaciens+110 g/L amino acids·24 g/L manganese zinc(transplanting dosage)or 120 g/L calcium·20 g/L magnesium(sealing dosage)may be employed to enhance the growth of tobacco plants and mitigate the occurrence of tobacco black shank.Additionally,25 g/L fludioxonil·37.5 g/L metalaxyl-M+10 billion/mL B.amyloliquefaciens+120 g/L calcium·20 g/L magnesium+4%metalaxyl-M·64%mancozeb can be utilized for the treatment of tobacco black shank during the initial incidence stage.

Association of cannabis use disorder with atrial fibrillation in young men without concomitant tobacco use:Insights from nationwide propensity matched analysis

BACKGROUND Recent data are inconclusive regarding the risk of arrhythmias among young cannabis users.Furthermore,many young adults use both cannabis and tobacco,which could add a residual confounding effect on outcomes.So,we studied young men who have cannabis use disorder(CUD)excluding tobacco use disorder(TUD)to understand their independent association with atrial fibrillation(AF)and related outcomes.AIM To study the association of CUD with AF and related outcomes.METHODS We used weighted discharge records from National Inpatient Sample(2019)to assess the baseline characteristics and mortality rates for AF-related hospitalizations in young(18-44 years)men in 1:1 propensity-matched CUD+vs CUD-cohorts without TUD.RESULTS Propensity matched CUD+and CUD-cohorts consisted of 108495 young men in each arm.Our analysis showed an increased incidence of AF in black population with CUD.In addition,the CUD+cohort had lower rates of hyperlipidemia(6.4%vs 6.9%),hypertension(5.3%vs 6.3%),obesity(9.1%vs 10.9%),alcohol abuse(15.5%vs 16.9%),but had higher rates of anxiety(24.3%vs 18.4%)and chronic obstructive pulmonary disease(COPD)(9.8%vs 9.4%)compared to CUD-cohort.After adjustment with covariates including other substance abuse,a non-significant association was found between CUD+cohort and AF related hospitalizations(odd ratio:1.27,95%confidence interval:0.91-1.78,P=0.15).CONCLUSION Among hospitalized young men,the CUD+cohort had a higher prevalence of anxiety and COPD,and slightly higher proportion of black patients.Although there were higher odds of AF hospitalizations in CUD+cohort without TUD,the association was statistically non-significant.The subgroup analysis showed higher rates of AF in black patients.Large-scale prospective studies are required to evaluate long-term effects of CUD on AF risk and prognosis without TUD and concomitant substance abuse.

Correlation Analysis between Well-cellar Early Transplanting of Robust Seedlings and Diseases in Shiyan Tobacco-growing Area

[Objectives]The paper was to investigate the relationship between the well-cellar early transplanting of robust seedlings and the prevalence of diseases in the Shiyan tobacco-growing area.[Methods]The relationship between disease occurrence and meteorological factors during the field growth period was examined by analyzing the prevalence of flue-cured tobacco virus diseases,brown spot,and total disease in the Shiyan tobacco-growing area before(2013-2017)and after(2018-2022)the well-cellar early transplanting of robust tobacco seedlings.[Results]The implementation of a well-cellar early transplanting technique of robust seedlings resulted in a reduction in the average incidence of tobacco virus disease,brown spot,and total disease by 0.83%,8.85%,and 7.91%,respectively,in comparison to the incidence observed prior to early transplanting.These findings suggest that early transplanting can significantly reduce the incidence of flue-cured tobacco diseases.Prior to the well-cellar early transplanting of robust tobacco seedlings,there was a significant(including highly significant)positive correlation between the incidence of brown spot and total disease and precipitation in August and September.The incidence of brown spot and total disease in tobacco plants was found to be significantly positively correlated with May precipitation and significantly negatively correlated with May sunshine hours following the well-cellar early transplanting of robust seedlings.The advancement of the transplanting period by 20 d resulted in a reduction in the growing period of tobacco plants in the field under autumn rains(late August to November)in western China.This effectively circumvented the suitable conditions for disease occurrence and can reduce the incidence of disease.[Conclusions]This study offers a framework for enhancing the quality and efficiency of flue-cured tobacco production in the northwest tobacco-growing area of Hubei.

Effects of Regulation of C/N Ratio Wheat Straw Application on Nitrogen,Phosphorus and Potassium Uptake in Tobacco

[Objective]The aim was to study the effects of regulation of C/N ratio wheat straw application on tobacco nitrogen,phosphorus and potassium uptake. [Method]Effects of regulation C/N ratio wheat straw application on the flue-cured tobacco yield,output value,nitrogen,phosphorus and potassium content and cumulative uptake of the upper,middle and bottom leaf were studied by using the field plot experiments at Banqiao town,Qujing city,Yunnan Province during the 2008-2009 summer growing seasons. [Result]The results showed that the application of wheat straw alone or after C/N regulation,could significantly increase tobacco production,potassium content,the potassium and nitrogen accumulation amount of leaf,and was more conducive to the potassium uptake of tobacco leaf with wheat straw application after C/N regulation. Compared with non-straw application,the yield of tobacco increased by 6.59%,3.58%,5.98%,8.80% with application of wheat straw alone,wheat straw and vetch,wheat straw and oilseed cake,wheat straw and urea nitrogen,the potassium content in tobacco leaf increased by 3.85%,7.76%,8.82%,11.21%,respectively,the total potassium cumulative amount of leaf increased by 10.71%,11.62%,15.32% ,21.01% and the total nitrogen cumulative amount increased by 9.76%,1.22%,8.14%,14.00%. However,the differences of tobacco leaf nitrogen content among the different treatments were not significant,the phosphorus uptake of tobacco leaf decreased. [Conclusion]application of high C/N ratio wheat straw in flue-cured tobacco production,which should be concerned not only to adjust C/N ratio by adding nitrogen,but also considering additional phosphorus application.

Cloning of cDNA Encoding Choline Monooxygenase from Suaeda liaotungensis and Salt Tolerance of Transgenic Tobacco

Betaine is a very effective osmoprotectant found in many organisms. In high plants, betaine is synthesized by oxidation of choline in two sequential steps: choline-->betaine aldehyde-->betaine. The first step is catalyzed by choline monooxygenase (CMO). In this study, the full-length CMO cDNA (1 820 bp) was cloned from halophyte Suaeda liaotungensis Kitag by RT-PCR and RACE. It included a 123 bp 5' UTR, a 368 bp 3' UTR and a 1 329 bp open reading frame encoding a 442-amino-acid polypeptide with 77%, 72% and 74% sequence identity compared to CMOs from spinach, sugar beet and Atriplex hortensis, respectively. The CMO open reading frame (ORF) was cloned and the plant expression vector pBI121-CMO was constructed. It was transferred into tobacco ( Nicotiana tabacum L. ev. 89) via Agrobacterium mediation. PCR and Southern blotting analysis showed that the CMO gene was integrated into tobacco genome. Transgenic tobacco plants contained higher amount of betaine than that of control plants and were able to survive on MS medium containing 250 mmol/L NaCl. Relative electronic conductivity demonstrated less membrane damage in transgenic plants as in the wild type.

Soil Fertility Properties of Tobacco Growing Area in Jiyuan

Soil fertility properties of the main tobacco growing area in Jiyuan （Shaoyuan,Wangwu,Xiaye and Daiyu） in west Henan Province were analyzed. Results showed that Jiyuan was one of the potential areas which could produce tobacco leaves with high quality. Its main properties of soli fertility were as follows：the content of total nitrogen,alkali-hydrolysable nitrogen,olsen-phosphorus and organic matters were suitable for high-quality tobacco production; especially,all the flue-cured tobacco growing areas in Henan Province were rich in available potassium; besides,the concentrate of water soluble chloride ion was at reasonable level. The problem was that the micro-elements such as Zn-DTPA and available boron content were at a low level in individual areas. Based on this survey,the recommendations for fertilization in Jiyuan such as stabilizing nitrogen rate,increasing phosphorus,stabilizing potassium,and applying boron commonly and supplementing zinc for the deficient soils were put forward.

Aphid-resistant Transgenic Tobacco Plants Expressing Modified gna Gene

A gene sequence coding for the precursor of Galanthus nivalis agglutinin (GNA) was modified by site-directed mutagenesis to change very low usage bias codons to higher usage bias ones for improvement of the gene expression in transgenic tobacco (Nicotiana tabacum L.) plants. Results from Western blot analysis of some of the transgenic tobacco plants showed that the expression level of GNA in plants transformed with the modified gene GNA34m reached 0.25% of total soluble proteins, while that of the GNA34 gene transgenic plants was 0.17%. Since the GNA expression level increased, the aphid resistance of GNA34m transgenic plants were also enhanced significantly as judged by a 71.0% aphid population inhibition in insect bioassay of GNA34m transformed plants and 63.7% for the plants transformed with the natural GNA34 gene.

Translocation and Distribution of Imidacloprid in Tobacco with Two Application Methods

[Objective] To compare the translocation and distribution of imidacloprid in tobacco with spray and root irrigation application methods. [Methods] Pot experiment in the greenhouse was carried out, and LC-MSMS was used to determine the con- tent of imidacloprid in different parts of tobacco plants （roots, stems, the upper, middle and lower leaves） at different time. [Results] The imidacloprid could be absorbed by root and could be transported to all parts of the tobacco plant after irrigating root, but the original deposition amount was larger and the transport efficiency was lower after spraying. [Conclusion] The translocation and distribution of imidacloprid by spraying was more uniform and the holding efficiency was better, but imidacloprid with root irrigation could act on leaf directly, and had better readily availability.

Study on Improving the Internal Quality of Tobacco Stems by Using Pectinase

[Objective] This study aimed to reduce the content of cell wall materials in tobacco stems and improve their internal quality. [Method] Pectinase was used to decompose cell wall materials in tobacco stems, followed by determination of the contents of four cell wall materials, six routine chemical components, as well as aroma constituents. [Result] Pectinase could effectively reduce the contents of cell wall materials in tobacco stems, with the largest decrease of 6.84%; after pectinase treatment,the content of reducing sugar in tobacco stems increased obviously, and the contents of total sugar, potassium ion, chloride ion and total nitrogen increased to varying degrees, of which the contents of potassium ion and reducing sugar displayed upward trends with the increase of pectinase concentration. Pectinase treatment significantly increased the contents of Maillard reaction products, with the most increase of 67.2%;the contents of carotenoid degradation products, phenylalanine degradation products and neophytadiene all increased to varying extents, and the contents of both Maillard reaction products and phenylalanine degradation products revealed ascending trends with the increase of pectinase concentration. [Conclusion] Pectinase treatment can effectively decompose cell wall materials in tobacco stems, improve routine chemical constituents, and increase the contents of aroma constituents.

Effects of Three Major Tobacco Curing Techniques on Raw Tobaccos

[Objective] The aim was to compare effects of three curing techniques （Chinese tobacco curing-method for improving tobacco quality and fragrance, Chi-nese （three-phase） tobacco curing technique, and Zimbabwe tobacco curing tech-nique） on quality of tobacco and to select optimal curing method. [Method] In Peng-shui county in Chongqing, tobacco variety K326 was chosen as test materials to conduct tobacco curing tests as per three techniques to analyze key components of raw tobacco, grade quality and evaluation quality. [Result] The content of starch in tobacco was reduced by Chinese tobacco curing-method for improving tobacco quality and fragrance, and the ratio of middle and high quality grade tobaccos improved by 1.8%-7.95%; average price increased by 1.64-3.21 yuan/kg; evaluation grade grew by 1.5-4.4. The technique is proved in enhancing tobacco fragrance quality and quantity as wel as improving and adjusting fragrance, taste and flavor. [Conclusion] Chinese （three-phase） tobacco curing technique improves tobacco quality and provides references for production demonstration areas of tobacco curing.

Novel Halophyte EREBP/AP2-type DNA Binding Protein Improves Salt Tolerance in Transgenic Tobacco

EREBP/AP2-type proteins are members of a large DNA binding protein (DBP) family found in plants. Some members like APETALA2 and AtDREB/CBF can regulate flower development and response to environmental stresses, respectively. To characterize transcription factors involved in plant responses to salt stress, we constructed cDNA library from salt-treated halophyte (Atriplex hortensis) and isolated a novel gene encoding EREBP/AP2-type protein from this library. This cDNA contained an ORF of 723 bp and a long 3'-Untranslated-Region (UTR) of 655 bp. The deduced amino acid sequence showed one conserved DNA binding domain of EREBP/AP2, thus the corresponding gene was named AhDREB1 with a calculated molecular mass of 26.1 kD. AhDREB1 under the control of CaMV 35S promoter was then transformed into tobacco and nine independent transgenic lines were obtained and subjected to long term salt stress. The results suggested that overexpression of AhDREB1 improved the salt tolerance in transgenic tobacco through functioning as a regulatory molecule in response to salt stress. Analysis of Arabidopsis genome in database resulted in dozens of EREBP/AP2-type homologous proteins, of which seven members showed high similarity to AhDREB1. Secondary structure analysis predicted similar arrangement of a-helix in their DNA binding domains.

Effects of Tobacco Curing on Accumulation of Chemical Components and Aroma Components in Tobaccos

[Objective]The aim was to explore effects of curing technique parameters on chemical components and aromatic material accumulation to formulate a suitable curing technique and for and to achieve tobacco scalding, drying and giving aromat- ic flavor. [Method] With tobacco variety KRK 26 as test materials, the test involved parameters of three curing-techniques in down, middle and upper parts of flue-cured tobaccos in an oven to measure chemical components and aromatic substances in tobaccos. [Result] The effects of curing techniques on total sugar and reducing sug- ar differed upon temperature and humidity. The contents of chemical components, such as total alkaloid, total N and the ratio of sugar/ alkali by moderate temperature and high humidity technique were of significant differences with those by moderate temperature and moderate humidity technique and with low temperature and low hu- midity technique; the chemical components by moderate temperature and moderate humidity were of insignificant differences with the treatment by low temperature and low humidity technique. Total amount of aroma components by different curing tech- niques from high to low was the treatment by low temperature and low humidity technique （461.72 μg/g）, the treatment by moderate temperature and moderate hu- midity technique （450.06μg/g） and the treatment by moderate temperature and high humidity technique （385.12μg/g）, suggesting the content of aromatic substances is high at low temperature and low humidity. [Conclusion] Moderate temperature and high humidity curing technique has significant effects on total alkaloid, total N and the ratio of sugar/ alkali of tobaccos and different curing techniques also affect the total amount of aromatic substances of flue-cured tobaccos.

Agroinoculation as a Simple Way to Deliver a Tobacco Mosaic Virus- Based Expression Vector

烟草花叶病毒(TMV)表达载体30B是一个目前广泛应用的植物病毒表达载体,但用其生产外源蛋白时,必须先将它体外转录成RNA,才能被用来接种宿主植物。由于RNA体外转录费用昂贵、操作复杂,因此限制了30B表达载体的进一步应用。针对这一不足,我们用农杆菌接种法(agroinoculation)接种该病毒载体,即将30B cDNA置于花椰菜花叶病毒(CaMV)的35S启动子和终止子之间,再将整个表达框架插入到农杆菌T-DNA的左边界和右边界之内,构建成质粒p35S-30B,将转入该质粒的农杆菌注射到植物的叶片中,30B cDNA随T-DNA进入植物细胞后,被转录成可自我复制的RNA形式,进而发生系统侵染。为了检测此接种方式的可行性,绿色荧光蛋白(GFP)报告基因被克隆到p35S-30B中,构建成p35S-30B∶∶GFP,用含有该质粒的农杆菌进行注射操作。证实该病毒载体可通过简便的农杆菌接种法侵染Nicotiana benthamiana,在被接种植物的系统叶中,GFP的表达量可占植物总可溶蛋白的5.2％。

Determination of Growth-promoting and Antagonistic Action of Endophytic Bacteria Strains Itb57 and Itb295 of Tobacco

[ Objective ] The paper was to study the growth-promoting and antagonistic action of endophytic bacteria strains Itb57 and Itb295 of tobacco to explore their functions in biological control. [ Method] The growth-promoting effects of bacterial suspension ~ff endophytic bacteria Itb57 and Itb295 on tobacco seedling un- der different treatment modes were studied using potting method in greenhouse. The antagonistic action of bacterial suspension of endophytic bacteria Itb57 and Itb295 on Phytophthora nicotianae, Alternaria alternata and Botrytis cinerea were measured by duel culture method. [ Result] Bacterial suspensions of enduphytic bacteria Itb57 and Itb295 had certain growth-promoting effects on tobacco seedling, which could significantly increase the fresh weight and dry weight in aerial part; the growth-promoting effect of soaking ＋ spraying and irrigating treatment was the best. Itb57 strain had good antagonistic action against P. nicotianae. A. alterna- ta and B. cinerea, while Itb295 strain only had good antifungal effect against P. nicotianae. [ Conclusion] The results provided basis for the study and application of tobacco endophytic bacteria strains Itb57 and Itb295 in biocontrol of tobacco diseases.