Tobacco (Nicotiana tabacum L.) is a globally important cash crop and the predominant natural source of nicotine. Previously, integrated transcriptomic and proteomic analyses identified NtABCG6L, an ABCG-family transporter, as a candidate mediator of nicotine transport. However, its specific function and underlying mechanism of action remain unresolved. In the present study, NtABCG6L co-localised with a plasma membrane marker and is preferentially expressed in roots. Root NtABCG6L transcript abundance was positively correlated with the nicotine translocation coefficient across developmental stages. Overexpression markedly increased nicotine translocation efficiency, leading to elevated nicotine accumulation in leaves. Yeast assays supported the involvement of NtABCG6L in nicotine transport. Transcriptomic profiling revealed that NtABCG6L overexpression triggered the co-expression of additional transport-related genes, thereby synergistically enhancing nicotine movement. Reduced root nicotine levels relieved feedback repression of negative regulators of nicotine biosynthesis (ASNA, speD and ETR), stimulated de novo nicotine synthesis, and promoted further transfer to leaves. Together, these results indicate that NtABCG6L contributes to root-to-leaf nicotine translocation and interacts with NtWBC in tobacco.

Nicotine is the major alkaloid in tobacco and plays a key role in determining tobacco quality. Previous studies have shown that overexpression of NtGSTU10 enhances nicotine accumulation in tobacco hybrids; however, the molecular mechanisms underlying this process remain largely unclear. In this study, we investigated the regulatory role of NtGSTU10 in nicotine synthesis and distribution using integrated transcriptomic and metabolomic analyses in NtGSTU10-overexpressing tobacco plants. Nicotine content and distribution between roots and leaves were quantified, and global transcriptional and metabolic profiles were analyzed to reveal molecular changes associated with NtGSTU10 overexpression. The results showed that NtGSTU10 overexpression was associated with increased nicotine accumulation in leaves and reduced nicotine levels in roots, resulting in significantly higher nicotine transport coefficients compared with wild-type plants. Transcriptomic analysis revealed coordinated changes in genes involved in nicotine biosynthesis, transport, and secondary metabolism. Metabolomic profiling indicated significant alterations in amino acid metabolism, nicotinic acid and nicotinamide metabolism, purine metabolism, sugar metabolism, and alkaloid biosynthesis pathways. Integrated transcriptome–metabolome analysis further identified coordinated regulation of glutathione metabolism, ABC transporters, and MATE transporter–encoding genes. Overall, these results reveal a regulatory network associated with NtGSTU10-mediated nicotine biosynthesis and transport, providing new insights into the molecular mechanisms underlying nicotine metabolism in tobacco.

Nicotine exhibits positive heterosis, and through its utilization, new tobacco varieties with ideal nicotine content have been bred. However, the potential mechanism underlying the increased transport and nicotine accumulation capacity in hybrids remain poorly understood. The purpose of this study was to reveal the regulatory role of the key gene NtGSTU10, which was identified during the early stages of nicotine heterosis. NtGSTU10-over expression lines were created through genetic transformation, and the nicotinic content, transport coefficient, and heterosis of NtGSTU10-over expression lines and wild-type tobacco plants were compared. The results suggested that the nicotine content in the leaves of V×OB7 (The over expression hybrids were produced by crossing Va116 as the female parent with OB7 as the male parent.) and V×OB12 (The over expression hybrids were produced by crossing Va116 as the female parent with OB12 as the male parent.) was significantly higher than that of the wild-type hybrid (V×B). Compared to the V×B, the nicotine transport coefficients of V×OB7 and V×OB12 were significantly increased by 39.50

Nicotine exhibits obvious heterosis, which can be used to create Nicotiana tabacum L. (tobacco) varieties with varying nicotine content. However, the reasons for the formation of nicotine heterosis and its relationship to nicotine transport and accumulation remain unknown. This study conducted a comprehensive analysis of six tobacco hybrids with varying heterosis levels and their parent materials from various aspects, such as phenotype, physiology, and transcriptomics. The results showed that the direct path coefficient of transport heterosis to nicotine heterosis was highest in hybrids, at 0.98, and a highly significant positive correlation between the two. The plant height, thick stalk circumference, large flow of tissue fluid in the stalk, and high nicotine concentration of tobacco were the underlying factors that led to the strong nicotine transport capacity of hybrids. The formation of nicotine transport heterosis in hybrids was mainly influenced by non-additive gene effects (accounting for 89.93%), with over-dominant effects playing a dominant role (accounting for 58.79%). Among non-additive expression DEGs, nicotine transporter related multi antimicrobial extrusion protein, drug/metabolite transporter, ABC family transporter, and glutathione S-transferase were significantly upregulated in hybrid strains. The RT-qPCR results indicated that these genes related nicotine transport also exhibited heterosis at the expression level. Our results revealed that the formation of nicotine heterosis is mainly achieved by enhancing the nicotine transport capacity in hybrids. The results are not only beneficial for promoting the theoretical study of nicotine heterosis in tobacco and the breeding and utilization of hybrids, but are also of great significance for guiding nicotine production and promoting its multipurpose utilization.

The photothermal sensitivity of tobacco refers to the degree to which tobacco responds to changes in light and temperature conditions in its growth environment, which is crucial for determining the planting area of cultivars and improving tobacco yield and quality. In order to accurately and effectively evaluate the photothermal sensitivity of tobacco cultivars, this study selected five cultivars and their hybrid combinations with significant differences planted under different ecological conditions from 2021 to 2022 as materials. The experiment was conducted in two locations with significant differences in temperature and light. We measured the agronomic traits and biomass of the experimental materials, and constructed an effective tobacco photothermal sensitivity evaluation model using principal component analysis, membership function, and regression analysis. The reliability of the model was evaluated by utilizing the photosynthetic characteristics, chlorophyll content, and antioxidant enzyme system activity of the experimental materials. The results showed that tobacco biomass is the most important principal component in agricultural traits, and the comprehensive evaluation model for tobacco photothermal sensitivity is: y = 0.4571y1 + 0.2406y2 + 0.1725y3, where the fitting coefficients R2 of y1, y2, and y3 are 0.945, 0.851, and 0.977, respectively; The photothermal sensitivity of the experimental materials was calculated using this model, and the comprehensive ranking of the 11 experimental materials is: G3 < G5 < G10 < G9 < G11 < G6 < G7 < G2 < G4 < G8 < G1. Conventional identification methods have found that G2, G4, G6, G7, G8, and G11 are sensitive materials, G3, G5, and G10 are insensitive materials, and G1 and G9 are intermediate materials. The consistency rate of the evaluation results of the two methods reached 90.91%. And there is a significant correlation between the agronomic traits selected in the model and the physiological indicators selected by conventional evaluation methods, providing a scientific basis for evaluating the light temperature sensitivity of tobacco cultivars using agronomic traits in this study. The results indicate that the photothermal sensitivity evaluation model established in this study provides an efficient, convenient, and reliable method for evaluating the photothermal sensitivity of tobacco.

BACKGROUND:Leaves are the nutritional and economic organs of tobacco, and their biomass directly affects tobacco yield and the economic benefits of farmers. In the early stage, our research found that tobacco hybrids have more leaves and larger leaf areas, but the performance and formation reasons of biomass heterosis are not yet clear.RESULTS:This study selected 5 parents with significant differences in tobacco biomass and paired them with hybrid varieties. It was found that tobacco hybrid varieties have a common biomass heterosis, and 45 days after transplantation is the key period for the formation of tobacco biomass heterosis; By analyzing the biomass heterosis of hybrids, Va116×GDH94 and its parents were selected for transcriptome analysis. 76.69% of the differentially expressed genes between Va116×GDH94 and its parents showed overdominant expression pattern, and these overdominant expression genes were significantly enriched in the biological processes of photosynthesis and TCA cycle; During the process of photosynthesis, the overdominant up-regulation of genes such as Lhc, Psa, and rbcl promotes the progress of photosynthesis, thereby increasing the accumulation of tobacco biomass; During the respiratory process, genes such as MDH, ACO, and OGDH are overedominantly down-regulated, inhibiting the TCA cycle and reducing substrate consumption in hybrid offspring; The photosynthetic characteristics of the hybrid and its parents were measured, and the net photosynthetic capacity of the hybrid was significantly higher than that of the parents.CONCLUSION:These results indicate that the overdominant expression effect of differentially expressed genes in Va116×GDH94 and its parents plays a crucial role in the formation of tobacco biomass heterosis. The overdominant expression of genes related to photosynthesis and respiration enhances the photosynthetic ability of Va116×GDH94, reduces respiratory consumption, promotes the increase of biomass, and exhibits obvious heterosis.

Heterosis, recognized for improving crop performance, especially in the first filial (F1) generation, remains an area of significant study in the tobacco industry. The low utilization of leaf veins in tobacco contributes to economic inefficiency and resource waste. Despite the positive impacts of heterosis on crop genetics, investigations into leaf-vein ratio heterosis in tobacco have been lacking. Understanding the mechanisms underlying negative heterosis in leaf vein ratio at the molecular level is crucial for advancing low vein ratio leaf breeding research. This study involved 12 hybrid combinations and their parental lines to explore heterosis associated with leaf vein ratios. The hybrids displayed diverse patterns of positive or negative leaf vein ratio heterosis across different developmental stages. Notably, the F1 hybrid (G70 × Qinggeng) consistently exhibited substantial negative heterosis, reaching a maximum of -19.79

BACKGROUND:Glutathione S-transferases (GSTs) are large and multifunctional proteases that play an important role in detoxification, protection against biotic and abiotic stresses, and secondary metabolite transportation which is essential for plant growth and development. However, there is limited research on the identification and function of NtGSTs.RESULTS:This study uses K326 and other six tobacco varieties (Hongda, HG, GDH11, Va116, VG, and GDH88) as materials to conduct comprehensive genome-wide identification and functional characterization of the GST gene in tobacco. A total of 59 NtGSTs were identified and classified into seven subfamilies via the whole-genome sequence analysis, with the Tau type serving as the major subfamily. The NtGSTs in the same branch of the evolutionary tree had similar exon/intron structure and motif constitution. There were more than 42 collinear blocks between tobacco and pepper, tomato, and potato, indicating high homology conservation between them. Twelve segmental duplicated gene pairs and one tandem duplication may have had a substantial impact on the evolution and expansion of the tobacco GST gene family. The RT-qPCR results showed that the expression patterns of NtGSTs varied significantly among tissues, varieties, and multiple abiotic stresses, suggesting that NtGST genes may widely respond to various abiotic stresses and hormones in tobacco, including NtGSTF4, NtGSTL1, NtGSTZ1, and NtGSTU40.CONCLUSIONS:This study provides a comprehensive analysis of the NtGST gene family, including structures and functions. Many NtGSTs play a critical regulatory role in tobacco growth and development, and responses to abiotic stresses. These findings offer novel and valuable insights for understanding the biological function of NtGSTs and the reference materials for cultivating highly resistant varieties and enhancing the yield and quality of crops.

Cytoplasmic male sterility (CMS) is critical in maximizing crop yield and quality by utilizing tobacco heterosis. However, the mechanism of tobacco CMS formation remains unknown. Using paraffin section observation, transcriptome sequencing, and TMT proteomic analysis, this study describes the differences in expression profiles in morphology, transcription, and translation between the sua-CMS tobacco line (MSYY87) and its corresponding maintainer line (YY87). According to the microspore morphology, MSYY87 began to exhibit abnormal microspore development during the early stages of germination and differentiation (androgynous primordium differentiation stage). According to transcriptomic and proteomic analyses, 17 genes/proteins involved in lipid transport/binding and phenylpropane metabolism were significantly down-regulated at both the mRNA and protein levels. Through further analysis, we identified some key genes that may be involved in tobacco male sterility, including β-GLU related to energy metabolism, 4CL and bHLHs related to anther wall formation, nsLTPs related to pollen germination and anther cuticle, and bHLHs related to pollen tapetum degradation. We speculate that the down-regulation of these genes affects the normal physiological metabolism, making tobacco plants show male sterility. SIGNIFICANCE: Cytoplasmic male sterility (CMS) plays a vital role in utilizing tobacco heterosis and enhancing crop yield and quality. We observed paraffin sections and conducted transcriptome sequencing and mitochondrial proteomics to examine the tobacco CMS line Yunyan 87 (MSYY87) and its maintainer line Yunyan 87 (YY87). The down-regulation expression of β-GLU resulted in insufficient ATP supply, which resulted in disordered energy metabolism. The down-regulation expression of 4CL, nsLTPs and bHLHs may affect the formation of anther wall and anther cuticle, pollen germination, as well as the degradation of pollen tapetum. These various abnormal physiological processes, the male sterility of tobacco is finally caused. The findings shed light on the molecular mechanisms of tobacco CMS and serve as a model for fertility research in other flowering plants.

Cold stress is a non-biological stressor that adversely affects tobacco yield and leaf quality. Plant photoreceptor proteins, which function as dual light-temperature sensors, play a vital role in temperature changes, making them crucial for responses to non-biological stressors. However, the regulatory mechanisms of PhyA in tobacco remain poorly understood. Therefore, in this study, we aimed to clone the NtPhyA gene from tobacco and generate overexpression (OE-NtPhyA) and mutant (KO-NtPhyA) constructs of NtPhyA. By assessing the physiological and biochemical responses of the mutants under cold stress and performing transcriptome sequencing, we determined the signalling mechanism of NtPhyA under cold stress. Comparative analysis with wild-type (WT) NtPhyA revealed that KO-NtPhyA exhibited increased seed germination rates and reduced wilting under cold stress. In additional, the degree of damage to leaf cells, cell membranes, and stomatal structures was mitigated, and the levels of reactive oxygen species (ROS) were significantly decreased. Antioxidant enzyme activity, net photosynthetic rate, and Fv/Fm were significantly enhanced in KO-NtPhyA, whereas the opposite effects were observed in OE-NtPhyA. These findings indicate that KO-NtPhyA augments tobacco tolerance to cold stress, implying a negative regulatory role of NtPhyA in tobacco during cold stress. Transcriptome analysis revealed that NtPhyA governs the expression of a cascade of genes involved in the response to oxygen-containing compounds, hydrogen peroxide (H2O2), ROS, temperature stimuli, photosystem II oxygen-evolving complex assembly, water channel activity, calcium channel activity, and carbohydrate transport. Collectively, our findings indicate that NtPhyA activates downstream gene expression to enhance the resilience of tobacco to cold stress.

以烟草Nicotiana tabacum抗旱品种NC82和干旱敏感品种云烟87幼苗为材料,利用PEG-6000对幼苗进行干旱胁迫处理,研究干旱胁迫对烟草不同品种Fv/Fm、SOD活性、POD活性、MDA含量等生理生化指标及NtDEGP5基因表达的影响,为进一步开展NtDEGP5基因的功能研究提供依据.结果表明,干旱胁迫对烟苗的Fv/Fm、SOD活性、POD活性、MDA含量有影响,随着干旱的持续,Fv/Fm呈逐渐下降趋势,POD、SOD活性和MDA含量呈先升高后降低的趋势;不同品种对干旱胁迫的响应有差异,在干旱胁迫0～9 h,云烟87幼苗的Fv/Fm降幅大于NC82,POD、SOD活性、MDA含量的增幅小于NC82,胁迫12 h后与对照差异不显著.干旱胁迫下不同品种、不同器官间的NtDEGP5基因表达有差异,云烟87幼苗根、茎、叶中的表达量均较低,NC82幼苗根中的表达量较低,但干旱胁迫9～12 h后叶和茎的表达量较高.NC82幼苗叶片NtDEGP5基因表达量与Fv/Fm、POD活性、MDA含量呈显著正相关.Fv/Fm、SOD活性、POD活性、MDA含量可作为烟草苗期抗旱性评价指标,NtDEGP5基因表达量与抗旱评价指标显著相关,该基因可能具有抗旱性功能.

Tobacco is an essential cash crop, but drought has become a major factor in the decline of global tobacco production as a result of changes in the global climate. The HtrA protease is an oligomeric serine endopeptidase that responds to stress in plants. DEGP5 is a member of the gene family that encodes HtrA protease, which promotes plant adaptation to adversity. The aim of this study was to investigate the role and mechanism employed by the DEGP5 gene in response to drought stress in tobacco. NtDEGP5-overexpression lines were obtained by genetic transformation and the phenotypes and transcriptomes of NtDEGP5-overexpression lines and wild-type (K326) tobacco seedlings were compared under drought stress. The results demonstrated that plants overexpressing NtDEGP5 exhibited greater drought tolerance. The differentially expressed genes involved in the regulation of drought tolerance by DEGP5 were enriched in metabolic pathways, such as plant-pathogen interaction and glutathione metabolism, with the plant-pathogen interaction pathway having the most differentially expressed genes. An analysis of the plant-pathogen interaction pathway revealed that these genes contributed to the suppression of plastid extracellular Ca2+ signaling and flagellin signaling to inhibit reactive oxygen species production, and that lower levels of reactive oxygen species act as a signal to regulate the activation of the antioxidant system, further balancing the production and removal of reactive oxygen species in tobacco seedlings under drought stress. These findings suggest that the NtDEGP5 gene can enhance the drought tolerance of tobacco by regulating the homeostasis of reactive oxygen species by inhibiting extracellular plastids.

Heterosis has greatly improved the yield and quality of crops. However, previous studies often focused on improving the yield and quality of the shoot system, while research on the root system was neglected. We determined the root numbers of 12 F 1 hybrids, all of which showed strong heterosis, indicating that tobacco F 1 hybrids have general heterosis. To understand its molecular mechanism, we selected two hybrids with strong heterosis, GJ (G70 × Jiucaiping No.2) and KJ (K326 × Jiucaiping No.2), and their parents for transcriptome analysis. There were 84.22% and 90.25% of the differentially expressed genes were overdominantly expressed. The enrichment analysis of these overdominantly expressed genes showed that “Plant hormone signal transduction”, “Phenylpropanoid biosynthesis”, “MAPK signaling pathway - plant”, and “Starch and sucrose metabolism” pathways were associated with root development. We focused on the analysis of the biosynthetic pathways of auxin(AUX), cytokinins(CTK), abscisic acid(ABA), ethylene(ET), and salicylic acid(SA), suggesting that overdominant expression of these hormone signaling pathway genes may enhance root development in hybrids. In addition, Nitab4.5_0011528g0020、Nitab4.5_0003282g0020、Nitab4.5_0004384g0070 may be the genes involved in root growth. Genome-wide comparative transcriptome analysis enhanced our understanding of the regulatory network of tobacco root development and provided new ideas for studying the molecular mechanisms of tobacco root development.

目前我国烟草杂交种种植越发广泛,不育系作为制备烟草杂交种的有利材料,在我国烟草种植中具有重要地位.为了探究烟草胞质雄性不育形成的分子机制,选用烟草不育系及其保持系,在花芽分化时期利用石蜡切片和线粒体蛋白组学技术结合生物信息学分析方法进行研究.结果表明,烟草雄性不育系的败育过程发生在发芽分化的雌雄蕊原基分化时期;蛋白组学分析共筛选出线粒体差异表达蛋白113个,呼吸代谢过程中的焦磷酸酶、异柠檬酸脱氢酶、苹果酸脱氢酶和磷酸己糖异构酶等关键调控蛋白酶的表达显著下调,ATP合酶的δ和α亚基表达上调;在线粒体蛋白的合成、修饰和运输过程中,核糖体RNA大亚基中L4e、L7和小亚基中SAe的表达下调,烯醇酶、内质网蛋白加工酶、蛋白二硫键异构酶等功能蛋白结构修饰酶表达下调,蛋白酶复合体的Rpt3和α5亚基表达下调.由上述结果推测,烟草胞质雄性不育由于线粒体蛋白的合成、修饰及导入过程受阻使线粒体功能紊乱,具体表现在线粒体呼吸代谢途径的蛋白酶表达下调及合成ATP受阻,不能为其在花粉形成时期小孢子的快速分裂分化提供充足的能量,抑制了小孢子的形成和发育,从而表现为雄性不育.本研究结果为进一步开展烟草雄性不育机理研究奠定了重要基础.

Potassium (K+) is essential for crop growth. Increasing the K+ content can often directly promote the improvement of crop yield and quality. Heterosis plays an important role in genetic improvement and leads to genetic gains. We found that the K+ content of tobacco showed significant heterosis, which is highly significant for cultivating tobacco varieties with high K+ content. However, the mechanism by which K+ content heterosis occurs in tobacco leaves is not clear. In this study, a comprehensive comparative transcriptome sequencing analysis of root samples from the hybrid G70 × GDH11 and its parental inbred lines G70 and GDH11 was performed to elucidate the importance of the root uptake capacity of K+ in the formation of heterosis. The results showed that 29.53% and 60.49% of the differentially expressed genes (DEGs) exhibited dominant and over-dominant expression patterns, respectively. These non-additive upregulated DEGs were significantly enriched in GO terms, such as metal ion transport and reaction, ion balance and homeostasis, ion channel activity, root meristem growth, and regulation of root hairs. The KEGG annotation results indicated that these genes were mainly involved in the pathways such as energy metabolism, carbohydrate formation, amino acid metabolism, and signal transduction. Further analysis showed that probable potassium transporter 17 (NtKT17) and potassium transporter 5-like (NtKT5), associated with potassium ion absorption, glutamate receptor 2.2-like and glutamate receptor 2.8-like, associated with ion channel activity, LOC107782957, protein detoxification 42-like, and probable glutamate carboxypeptidase 2, associated with root configuration, showed a significantly higher expression in the hybrids. These results indicated that the over-dominant expression pattern of DEGs played a key role in the heterosis of K+ content in tobacco leaves, and the overexpression of the genes related to K+ uptake, transport, and root development in hybrids helped to improve the K+ content of plants, thus showing the phenomenon of heterosis.

含梗率是烟叶的重要经济性状和物理特性指标,其测定方法过程繁琐、时间长,在品种选育中难以应用于大量品系鉴定和选择.为快速地测定含梗率,本研究设置杀青和烘烤干燥方式、叶梗分离和不分离处理以及0、5％、10％、15％和20％共5种烤后烟叶平衡含水率处理,测定不同品种间各处理的烟叶含梗率.结果表明,不同品种间烟叶含梗率相差极显著,烟草叶片梗的生长发育受遗传控制,说明选育含梗率低的品种是降低烟叶含梗率的有效途径;采用烘烤干燥方式的烟叶含梗率极显著高于杀青干燥方式,两种干燥方式间的烟叶含梗率差异极显著,相关系数为0.98,回归方程为y=1.615 9x+5.203 9;叶梗分离和不分离干燥后的烟叶含梗率差异极显著,叶梗分离后杀青干燥与不分离烘烤的烟叶含梗率的差异达到极显著水平,相关系数为0.93,回归方程为y=1.2299x-2.0705;当含水率在0～20％时,烟叶含梗率测定结果差异不显著.因此,在研究烟叶含梗率的遗传和进行新品系烟叶含梗率鉴定选择时,可采用将成熟烟叶的叶梗分离后进行杀青干燥,冷却后即可测定烟叶含梗率,根据测定值与对照品种烟叶含梗率的高低进行取舍,或采用回归方程预测该品系烘烤后的烟叶含梗率.成熟烟叶叶梗分离后杀青干燥测定烟叶含梗率的方法能提早鉴定时间、提高鉴定效率,可及时、快速、准确地对育种材料烟叶含梗率进行鉴定选择.

Background The filamentous temperature-sensitive H protease (ftsH) gene family plays an important role in plant growth and development. FtsH proteins belong to the AAA protease family. Studies have shown that it is a key gene for plant chloroplast development and photosynthesis regulation. In addition, the ftsH gene is also involved in plant response to stress. At present, the research and analysis of the ftsH gene family are conducted in microorganisms such as Escherichia coli and Oenococcus and various plants such as Arabidopsis, pear, rice, and corn. However, analysis reports on ftsH genes from tobacco (Nicotiana tabacum L.), an important model plant, are still lacking. Since ftsH genes regulate plant growth and development, it has become necessary to systematically study this gene in an economically important plant like tobacco. Results This is the first study to analyze the ftsH gene from Nicotiana tabacum L. K326 (NtftsH). We identified 20 ftsH genes from the whole genome sequence, renamed them according to their chromosomal locations, and divided them into eight subfamilies. These 20 NtftsH genes were unevenly distributed across the 24 chromosomes. We found four pairs of fragment duplications. We further investigated the collinearity between these genes and related genes in five other species. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis identified differential expression patterns of NtftsH in different tissues and under various abiotic stress conditions. Conclusions This study provides a comprehensive analysis of the NtftsH gene family. The exon-intron structure and motif composition are highly similar in NtftsH genes that belong to the same evolutionary tree branch. Homology analysis and phylogenetic comparison of ftsH genes from several different plants provide valuable clues for studying the evolutionary characteristics of NtftsH genes. The NtftsH genes play important roles in plant growth and development, revealed by their expression levels in different tissues as well as under different stress conditions. Gene expression and phylogenetic analyses will provide the basis for the functional analysis of NtftsH genes. These results provide a valuable resource for a better understanding of the biological role of the ftsH genes in the tobacco plant.

运用生物信息学分析方法,通过对烟草(Nicotiana tabacum)全基因组数据中的Trihelix家族基因的理化性质、染色体分布、染色体共线性、基序组成、基因结构、顺式作用元件及其低温处理下的表达进行完整的鉴定分析,初步解析烟草Trihelix家族成员的结构与功能.从普通烟草中鉴定出32个Trihelix基因,分为GT-1、GT-2、GTγ、SH4、SIP1等5个亚家族;32个NtTH基因有着10种分布不均匀的基序,且有不同的基因结构,但在同一个亚家族内有相似性;烟草与番茄(Lycopersicon esculentum)、拟南芥(Arabidopsis thaliana)、水稻(Oryza sativa)存在同源的Trihelix基因,普通烟草Trihelix家族自身也存在共线性基因;鉴定出13种不同类型的顺式元件,主要与非生物胁迫、激素和生长发育有关,其中ABRE和MeJA是最多的两个顺式元件,表明NtTH基因的功能主要与非生物胁迫和生长发育响应调控有关;烟草NtTH3和NtTH16等11个基因在对低温胁迫的响应方面有着重要作用.本研究挖掘到与烟草抗冷有关的基因,为烟草抗冷性遗传改良提供了理论依据.

BACKGROUND:The basic leucine zipper (bZIP) transcription factor (TF) is one of the largest families of transcription factors (TFs). It is widely distributed and highly conserved in animals, plants, and microorganisms. Previous studies have shown that the bZIP TF family is involved in plant growth, development, and stress responses. The bZIP family has been studied in many plants; however, there is little research on the bZIP gene family in tobacco.RESULTS:In this study, 77 bZIPs were identified in tobacco and named NtbZIP01 through to NtbZIP77. These 77 genes were then divided into eleven subfamilies according to their homology with Arabidopsis thaliana. NtbZIPs were unevenly distributed across twenty-two tobacco chromosomes, and we found sixteen pairs of segmental duplication. We further studied the collinearity between these genes and related genes of six other species. Quantitative real-time polymerase chain reaction analysis identified that expression patterns of bZIPs differed, including in different organs and under various abiotic stresses. NtbZIP49 might be important in the development of flowers and fruits; NtbZIP18 might be an important regulator in abiotic stress.CONCLUSIONS:In this study, the structures and functions of the bZIP family in tobacco were systematically explored. Many bZIPs may play vital roles in the regulation of organ development, growth, and responses to abiotic stresses. This research has great significance for the functional characterisation of the tobacco bZIP family and our understanding of the bZIP family in higher plants.

为解析烟草黄叶突变体叶色黄化机制,本研究以黄叶突变体、'黄叶K326,和'K326,为试验材料,从叶绿素含量及转录水平两个方面开展了研究.结果表明,两种黄叶材料整个生育期叶片中叶绿素含量显著低于'K326',成苗期差异最大,黄叶突变体、'黄叶K326'叶片的叶绿素含量分别为'K326,的58.57％和52.07％;通过转录组分析发现,两种黄叶材料与'K326'间有935个DEGs,这些DEGs涉及萜类生物合成、卟啉和叶绿素代谢、RNA修饰加工等过程;进一步分析发现叶绿素合成中编码镁螯合酶的CHLD、CHLH基因在两种黄叶材料叶片中表达量显著下调,筛选到14个叶绿体发育及分化有关的DEGs,包括EMB2654、PGR3、 GLB1、WAXY等基因,这些DEGs在两种黄叶材料大部分表现为下调.说明该黄叶突变基因可能通过影响CHLD、CHLH、EMB2654、PGR3、RAP等基因表达,使得叶绿体发育不良,叶绿素含量降低,引起叶色黄化.本研究结果为突变基因的克隆及进一步功能分析提供理论依据.