In order to study the effect of drought stress on physiological characteristics of grafting flue-cured tobacco,using KRK26 as scion, KRK26,K326 and Anyan 2 as rootstock,analysing and discussing root morphology, plant morphology and physiological indexes of resistance in pot culture under different treatment. The results indicated that under drought stress conditions at early period, the relative content of chlorophyll (SPAD readings) decreased, while the content of proline, superoxide dismutase (SOD) activities, catalase (CAT) activities and peroxidase (POD) activities in flue-cured tobacco demonstrated an increasing trend. The root length,surface area,plant height,stem girth, node spacing and LAI of the grafted tobacco plants showed a decreasing trend,the content of proline continued to increase in both grafted seedlings and non-grafted seedlings with the aggravation of drought stress when tobacco leaves were turning to mature, whereas, the SPAD readings, SOD activities, CAT activities and POD activities all demonstrated a decreasing trend. The speed of decreasing in different root grafted was slower than that in own root grafted. Compared with KRK26/K326 and KRK26/KRK26, KRK26/Anyan 2 had greater parameters under drought stress, but the SPAD readings did not have significant difference. All the results showed that less damage was made to KRK26/Anyan 2 than KRK26/K326 and KRK26/KRK26 under drought stress, and KRK26/KRK26 suffered the most serious damage. According to correlation analysis, there was a certain correlation between morphological indexes and resistance indexes of grafting flue-cured tobacco. In conclusion, there were obvious differences among grafted tobacco in physiological characteristics, and there response to soil drought. The order of drought resistance was KRK26/Anyan 2, KRK26/K326 and KRK26/KRK26 in turn from strong to weak, based on the main root morphology,plant morphology,physiological characteristics under drought stress.

To study the regulatory function of ethylene in plant stress tolerance,over 40 ethylene insensitive tobacco mutants were obtained from a genetic screen based on the typical seedling phenotype to ethylene in darkness,named "triple response",and most of the mutants displayed chilling resistance.The present study chose 4 mutant strains for further analyses in their chilling tolerance,physiological basis,and cold-regulated gene expressions.Under low temperature (0℃) stress,the electrolyte permeability of the tobacco ethylene insensitive mutants was significantly lower than that of the wild type,while the activities of SOD,POD and catalase were higher than those of the wild type.Further study indicated that the cold-induced genes showed highly transcription level under low temperature (0℃) stress. And,the transcripts levels of the downstream ERFs in the ethylene signal transduction pathway in the mutants were altered in the tobacco mutants.These data provide a direct molecular evidence for the strong resistance of the tobacco ethylene insensitive mutants to chilling stress.This study not only provides a new evidence for the relationship between ethylene signaling and chilling stress,but also lays a foundation for the use of biotechnology to improve crop stress resistance.

In order to realize the application of PRPs genes in plant genetic engineering,the GmPRP and SbPRP from soybean were cloned into plant expression vector of pRI101,respectively,and then introduced into tobacco by Agrobacterium-mediated transformation.Two positive transgenic tobacco plants of GmPRP and four positive transgenic tobacco plants of SbPRP were obtained.The transgenic tobacco plants were treated with salt,drought and cold stresses.The results showed that the contents of proline and soluble sugar in SbPRP transgenic plants were significant higher than wild-type plants and the contents of malondialdehyde in SbPRP transgenic plants were significant lower than wild-type plants under salt stress.While the contents of proline,soluble sugar,and malondialdehyde in GmPRP and SbPRP transgenic plants had no significant differences compared to wild-type plants under drought stress.The contents of proline in GmPRP and SbPRP transgenic plants were both significant higher than wild-type plants and the contents of malondialdehyde in GmPRP and SbPRP transgenic plants were both lower than wild-type plants under cold stress.These data indicated that the transgenic tobacco plants constitutively expressing SbPRP showed an increased tolerance to salt and cold stresses and the transgenic tobacco plants constitutively expressing GmPRP showed an increased tolerance to cold stress,which may provide a way toward the application of them.

In order to study the influence of different application amounts of charcoal on the microbial diversity in tobacco rhizosphere soil, with the rhizosphere soil of flue-cured tobacco variety Yunyan 87 as the research object, we compared the situation by applying different amounts of charcoal, and conducted high-throughput sequencing of rhizosphere soil ITS2 region and 16S rDNA-V4 region with progressive treatment with 3 application amounts of charcoal; through bioinformatics analysis of data, we obtained the OTU abundance, distribution,α diversity, community species composition and abundance information of microorganisms in rhizosphere soil when different treatment methods were used, and conducted PCA clustering analysis and UPGMA clustering analysis of the community composition and abundance. The results showed that within the application scope of 50-150 g/tree, by increasing the application amounts of charcoal, it could increase the variety diversity and distribution uniformity of bacteria in rhizosphere soil, while it would reduce the variety diversity and distribution uniformity of fungus; compared to the control group where no charcoal was applied, after applying the charcoal with the amounts of 50, 100,150 g/tree, the abundances of Proteobacteria bacteria had declined by 4.1%, 2.7% and 0.7% respectively; the abundances of Acidobacteria bacteria increased by 10.4%, 8.1% and 7.7% respectively; the abundances of Actinobacteria bacteria were all lower than the abundance of control group; the difference in abundance of Gemmatimonadetes bacteria between various groups was very small. After applying the charcoal with the amount of 50 g/tree, the abundance of Zygomycota fungus had declined by 12.38% compared to the control group(50.92%), and then, with the increased of the application amount of charcoal, the abundance of Zygomycota fungus gradually increased to 53.68%; on the contrary, after applying the charcoal with the amount of 50 g/tree, the abundance of Ascomycota fungus had increased by 10.15% compared to the control group(30.63%), and then, with the increased of the application amount of charcoal, the abundance of Ascomycota fungus gradually declined to 29.11%; after applying the charcoal with the amount of 50 g/tree, the abundances of Basidiomycota and Chytridiomycota funguses almost had no change, and then, with the increased of the application amount of charcoal, the abundances of Basidiomycota and Chytridiomycota funguses presented the trend of increased first, and then declined; various treatment methods did not have significant influence on the abundance of Glomeromycota fungus. By studying the influencing method and action rules of charcoal application on the micro-ecology of tobacco rhizosphere, it can provide theoretical basis to the application of charcoal in tobacco field.

To select the antagonistic bacterial strain that suited for high quality tobacco area of Anhui,the study on the antagonistically antibacterial effects of three kinds of antagonistic fermentation and the factors by the broth optical density and plate count.The results were that:three antagonistic strains had the better antibacterial effects;5,10,20,40,80 times concentration gradients had high optical density(OD) than the control(CK),and over 57%,reached to a significant level;The antagonistic order was AKJK-2013-02 > AKJK-2013-13 > AKJK-2013-11. The antibacterial effects were positively correlated with the fermentation time,and were weakened increasing storage time,and over 83.5% after storage 28 d.Three antagonistic strains had broth certain development values and application prospects.

In order to explore the effect of different forms of nitrogen supply on flue-cured tobacco's curing characteristics. A field experiment,using K326(Nicotiana tabacum L.)as experimental material,with five different forms of nitrogen supply that N1(100% nitrate nitrogen),N2(30% ammonia nitrogen + 70% nitrate nitrogen),N3(50% ammonia nitrogen + 50% nitrate nitrogen),N4(70% ammonia nitrogen + 30% nitrate nitrogen)and N5(100% ammonia nitrogen)were conducted to study the effects of different treatments water,chlorophyll,polyphenol oxidase and malondialdehyde contents in leaves of tobacco leaves were compared,and the economic characters of flue-cured tobacco leaves were compared.The results showed that different nitrogen supply had different effects on the baking characteristics of flue-cured tobacco under 165 kg/ha nitrogen application rate.The water loss rate of tobacco leaves treated with 30% ammonia nitrogen+70% nitrate nitrogen during the curing process was close to the mean value of the water loss rate in 72 hours,and the chlorophyll degradation rate and the water loss rate was coordinated and synchronized.The activity of polyphenol oxidase in tobacco leaves was the lowest,the accumulation of malondialdehyde was slow and the membrane lipid peroxidation level was the lowest.In addition,the treatment of 30% ammonia nitrogen+70% nitrate nitrogen had the proportion of high-grade tobacco and the highest value.It could be seen that the tobacco leaf curing characteristics and leaf quality could be obtained by using 30% ammonia nitrogen+70% nitrate nitrogen in the northern part of Guangdong.

In order to study the effects of different amount of biochar application combined with nitrogen fertilizer on the growth of flue-cured tobacco and the main chemical composition of tobacco leaves.Yunyan 87 was selected as testing material and a field experiment was designed to study the effects of nine different amount of biochar application combined with nitrogen fertilizer on the growth of flue-cured tobacco and the main chemical composition of tobacco leaves.The results showed that biochar application combined with nitrogen fertilizer could regulate and promote the growth of flue-cured tobacco,accelerate the speed of the leaves,but amount of biochar application was not positively correlated with the role of promotion tobacco growth,when applied to the biochar more than 3 750 kg/ha,and nitrogen fertilizer at 112.5 kg/ha,the role in promoting tobacco growth gradually decreased.Biochar application combined with nitrogen fertilizer could promote root growth,and improve the amount of dry matter accumulation of flue-cured tobacco.Coordinate the content of total sugar and reducing sugar,decline the content of starch,and improve the content of potassium in tobacco leaves and improve the combustibility of tobacco leaves.At the same time,it could also improve the ratio between sugar and nicotine,the ratio between sugar and nitrogen and the ratio between sugar and nitrogen of tobacco leaves.It was harmful to improve the ratio between sugar and nitrogen and the ratio between potassium and chlorine of tobacco leaves that a lower proportion of biochar application combined with nitrogen fertilizer that was 3 000 kg/ha biochar and 75.0 kg/ha nitrogen fertilizer.It was concluded that 3 750 kg/ha biochar and 112.5 kg/ha nitrogen fertilizer was the optimal proportion which had faster growth of tobacco plant and the appropriate content of main chemical composition of tobacco leaves.

Cloned the tobacco potassium transporter gene and predicted its structure, and analyzed their evolutionary relationships and functions, to lay the foundation for the study of tobacco potassium absorption mechanism.In this study, a homologous gene of a potassium transporter was cloned by RT-PCR from K326.Sequences analysis showed this gene contained 2 532 bp and coded 844 amino acid residues, and the calculated molecular mass was 93.1 kDa with the theoretical isoelectric point(pI) was 7.2.Homology analysis suggested that the gene had a high homology with the potassium transporter 12 of the Nicotiana tomentosiformis and Nicotiana sylvestris, so it was named as NtKT12.Protein structure and function analysis showed that NtKT12 has 12 transmembrane domains.Expression patterns showed that the expression level was the highest in the roots.Expression patterns under low potassium treatment suggested NtKT12 expression level was significantly higher after 6, 24 h than the control.These results provided some basis for potassium function analysis of NtKT12.

The overexpression and inhibition of expression of transgenic tobacco plant with 2-Cys Prx (Longjiang 911), non transgenic tobacco were chosen to investigate the effects of simulated acid rain on their growth, physiological features and photosynthesis.The results showed that simulated acid rain at pH 4.0 had no significant effects on the plant height, leaf area and specific leaf weight, but at pH 2.5, the plant height of overexpression and inhibition of expression of transgenic tobacco plant with 2-Cys Prx reduced significantly, With the pH value of the simulated acid rain decreased, chlorophyll content, nitrate reductase activity, soluble protein content, superoxide dismutase and ascorbate peroxidase activity, net photosynthetic rate(Pn), stomatal conductance(Gs), transpiration rate(Tr), the actual photochemical efficiency of PSⅡ(Φ_PSⅡ), photochemical quenching coefficient(qP), potential photochemical efficiency of PSⅡ(Fv/Fo) and cell membrane stability index decreased, the non-photochemical quenching(qN) and hydrogen peroxide content increased, but at the same pH value, these above-mentioned indexes of overexpression of transgenic tobacco plant with 2-Cys Prx were better than inhibition of expression of transgenic tobacco plant with 2-Cys Prx and non transgenic tobacco plant.The results suggest that enhanced expression of 2-Cys Prx in tobacco plant can promote the capability of tobacco against acid rain, the capability of utilizing nitrate nitrogen, and remove of excess H₂O₂ while APX activity decreases, and enhance the photosynthetic capability of tobacco.

Potassium channel is the main protein of plant uptake and translocation K⁺,and SKOR (Stelar K⁺ outwaed rectifier) belongs to Shaker channel family exogenous rectifier,which plays a key role in response to low potassium stress response in plants.In order to study the function and role of tobacco NtSKOR gene in abiotic stress response,one NtSKOR gene was cloned from Nicotiana tabacum K326 with homologous cloning strategy,gene expression patterns were analyzed by Real-time quantitative PCR,and their physicochemical properties,domains,phosphorylation sites and evolutionary relationships of proteins were predicted by bioinformatic analysis. Bioinformatics analysis showed that this gene contained 2 484 bp and encoded 827 amino acid. The predicted molecular weight was 94.75 ku and the isoelectric point (pI) was 6.52. The largest secondary structure element of this protein was α-helix,and the smallest was β-turn. NtSKOR contained six transmembrane domains(S1-S6),with three different kinase phosphorylation sites for serine,threonine and tyrosine. Phylogenetic analysis showed that the protein had 99% homology with Nicotiana sylvestris and 96% homology with Nicotiana tompentosiformis,thus it was named as NtSKOR. Expression patterns showed that the gene was expressed in roots,stems,leaves and flowers in mature stage,which had the highest expression in roots and the lowest expression level in flowers. Expression patterns under abiotic stress indicated the gene could respond rapidly to the adverse conditions of low potassium,high salt,drought,H₂O₂,ABA and 4℃. This suggests that NtSKOR gene plays an important regulatory role in tobacco abiotic stress,and the results provide a theoretical basis for further in-depth study of the NtSKOR function.

To investigate the function of JsWRKY1, a constitutive expression vector of JsWRKY1 was constructed and transferred into Nicotiana tabacum L.cv Xanthi.There were no visible differences between the positive transgenic plants and WT.The expression levels of several defense-related genes MnSOD, Cu/ZnSOD, CN, NADPH oxidase, and PR1 resistance gene were up-regulated in the transgenic tobacco lines,and the SOD,APX and POD showed significantly higher activities in the transgenic lines than in wild type under normal conditions or after inoculation with C.gloeosporioides. The crude protein extract of transgenic tobacco lines inhibited the hyphal growth of the following four fungi, Botrosphaeria dothidea, Gibberella moniliformis, C.gloeosporioides and Fusarium oxysporum at different degrees.The antifungal activity in vitro plates demonstrated that the activities of SOD in the transgenic tobacco lines were significantly higher than those in WT.Moreover,the transgenic tobacco plants showed strong resistance after inoculation with C.gloeosporioides in the leaves.In conclusion,the JsWRKY1 is a positive transcription factor of J.sigiuata regulating the defense response to pathogens.

To explore the effect of different leaf age on the yield and quality of flue-cured tobacco,the main cultivars K236 in Luoping tobacco-growing area of Yunnan were used as test materials to construct different flue-cured tobacco varieties with different leaf age. Photosynthetic potential in growth period and economic characters of post-baked tobacco leaf were analyzed. The results showed that with the increase of transplanting age,the survival rate of tobacco seedlings increased first and then decreased,while the field growth period increased; With the advance of fertility in the field of flue-cured tobacco,the photosynthetic potential (LAD) of the treatments decreased first and then increased,and the total LAD of the treatments was the highest in 5 leaves transplanted tobacco seedlings,which was 20.14% higher than that of 6 and 8 leaves respectively,14.82%. The mean leaf angle (MLIA) of the population increased first and then decreased with the increase of leaf age,while the extinction coefficient (K)was an increasing trend.The leaf tobacco leaves with 5 leaves were transplanted with appropriate chemical components and the quality was the best,followed by 4 leaves;6,7,8 leaves,because of its reducing sugar,starch,potassium content does not meet the requirements of high-quality tobacco chemical indicators,poor quality;With the increase of transplanting age,economic traits showed a trend of increasing first and then decreasing. Therefore,the optimum tobacco leaf transplanting age of tobacco leaves in Luoping tobacco-producing areas in Yunnan is 5-leaf-stage,which can shorten the period of nursery and shorten the time of cutting and reduce the time when the high yield value can be maintained. Such as smoke and the proportion of medium and high smoke,improve the grade structure and site structure.

In order to determine the reasonable ratio of water and nitrogen in the provisonal planting period of tobacco seedlings.The effects of growth and photosynthesis in leaves of tobacco seedlings was studied under water and nitrogen coupling treatment, when the relative water content of soil is 25% and 50%, the net photosynthetic rate and biomass increased with the increase of nitrogen fertilizer increased, but the relative water content of soil reached 75%, the net photosynthetic rate and biomass were both no difference under different nitrogen fertilizer application.Both of water and nitrogen fertilizer on net photosynthetic rate and biomass were positive correlation, two factors on the effects of net photosynthetic rate and biomass order for soil relative water content > nitrogen fertilizer, and two factors have the most suitable range.By comprehensive analysis suggesting that maintained the soil relative water content at 53%, application nitrogen fertilizer amount 0.49 g/kg could be recommended as the best combination of water and nitrogen in this experimental condition, while that the net photosynthetic rate and biomass reached 8.976 9 μmol/(m²·s) and 0.894 6 g, respectively.

2C protein phosphatase (PP2C) is a key component in the ABA signal transduction pathway and plays a pivotal role in plant growth and development,cell cycle regulation and adaptation to adversity stresses.To explore the function of the PP2C gene in tobacco adaptation to abiotic stress,a PP2C homologous gene was cloned from the tobacco cultivar K326,which contained a 1 617 bp ORF encoding 538 amino acid. The homology analysis showed that the gene had high homology with PP2C16 of Nicotiana tomentosiformis. So it was named NtPP2C16. Bioinformatics analysis showed that the NtPP2C16 catalytic region had 11 structural sub-regions which were relatively conservative in the PP2C family evolution. qRT-PCR analysis revealed that the expression of this gene was significantly induced by ABA and H₂O₂ signal molecules,and responded to drought,high salt,low temperature and low potassium stresses. NtPP2C16-pBI121 overexpression vector was constructed successfully,the results provided some basis for analysis of NtPP2C16 responsing to abiotic stresses in tobacco.

Black shank disease is one of the main diseases of tobacco production.The screening,identification of the disease resistance and genetic analysis of tobacco germplasm resources are the base of breeding for disease resistance. In this study,we used Physiological race 1 black shank to identify the resistance to black shank of 49 tobacco germplasm resources and used SSR markers to analysis genetic relationship. The results showed:Among them 24 were resistant,including dayeyongyan,G80,E9,MS212-8;7 were moderate resistant;6 were moderate susceptible;12 were susceptible;6 were high susceptible.The average effective number of alleles of 49 tobacco germplasm resources was 3.06(1.31),and the average Shannon's information index was 1.18(0.36);The 49 germplasm materials were classed into 4 groups at the position of coefficient of 0.66 by the 23 SSR markers. The first group was resistance variety K326;the second group included 6 germplasm resources;the third group included 4 susceptible germplasm resources;the fourth group included 38 germplasm resources. The most of resistance to black shank germplasm was clustered in the fourth group,suggesting the genetic basis of the resistance to black shank germplasm resources was narrow.

To study the function and mechanism of dehydrin in early embryogenesis of plant,egg cells were isolated from tobacco to construct a cDNA library,and a gene named NtDEH1 were found.The full sequence of NtDEH1 were obtained by RACE,genome cloning and bioinformatics analysis showed that NtDEH1 included a 651 bp CDS region and a 535 bp intron.NtDEH1 which contained 217 amino acids were hydrophilic and acidic,the theory isoelectric point was 5.27.The amino acid homology of NtDEH1 compared Nicotiana tabacum to Nicotiana tomentosiformis,Nicotiana sylvestris,Capsicum annuum,Solanum tuberosum,Solanum lycopersicum and Salvia miltiorrhiza showed that NtDEH1 homologous sequences in all these species were conserved and belonged to SK₂ type.5' flanking sequence of NtDEH1 gene was also obtained by genome-walking,and the promoter activity of 5' flanking sequence was checked by transient gene expression.The result laid a foundation in researching the role of NtDEH1 gene in plant reproduction.

In order to measure the effect and action mechanism of cadmium(Cd) on the photosynthetic characteristics in the leaves of flue-cured tobacco,flue-cured tobacco was cultured in a solution containing different concentrations of Cd. The effects of Cd stress on the chlorophyll content,photosynthetic gas exchange and chlorophyll fluorescence parameters in the flue-cured tobacco leaves were investigated. The results showed that the chlorophyll content in the flue-cured tobacco leaves declined as the Cd concentration increased. The chlorophyll a content,in particular,was reduced to a much greater extent than chlorophyll b content. The photosynthetic capacity in the leaves of flue-cured tobacco was reduced mainly associated with the stomatal conductance until the Cd concentration reached 75 μmol/L. But,when Cd concentration reached 100 mol/L,the cause of flue-cured tobacco leaf photosynthetic capacity decreased to were the stomatal and non stomatal factors common restrictions. The non-photochemical queching(NPQ) and the quantum yield of light-dependent and ΔpH-and xanthophyll-mediated regulated thermal dissipation(Y_NPQ) was increased below the 50 μmol/L Cd,that means the flue-cured tobacco leaf was mainly by increasing non-radiative energy dissipation mechanisms by xanthophyll cycle to reduce the flue cured tobacco in excess excitation energy,but with the further increase of Cd concentration,NPQ and Y_NPQ was reduced,which leads to the excess light energy(1-q_P)/NPQ,the quantum yield or flux of thermal dissipation in non-functional PSⅡ and the degree of photoinhibition of PSⅡ reaction center increased dramatically,at this point,the heat dissipation and the reaction center inactivation was the major photoprotective mechanisms in leaves of flue-cured tobacco to defense the Cd poisoning. This study would provide some basic data for seeking Cd-resistant mechanism of tobacco.

This study laid the theoretical foundation for the study of the function and structure of peroxidase genes in tobacco and cloned the cDNA of peroxidase gene NtPOD1 from tobacco cultivar K326 by homologous cloning and analyzed the bioinformatics. At the same time,qRT-PCR method was used to analyze the expression pattern of tissue and organ of this gene and its stress response. The results showed that the total length of cDNA was 981 bp,encoding 326 amino acid residues,the predicted molecular weight was 37.19 ku,and the isoelectric point was 8.89. Bioinformatics analysis showed that the protein was a hydrophilic protein containing four conserved disulfide bonds and two conserved calcium binding sites in the domain,which may be located in extracellular(including cell wall).The class Ⅲ secretion oxidase of the dependent peroxidase superfamily had high homology with Nicotuana attenuata POD42, Nicotiana sylvestris POD42,Solanum tuberosum POD42 and so on. The gene was expressed in tobacco roots,stems,leaves and flowers,with the highest expression in leaves and the lowest expression in flowers. Meanwhile, NtPOD1 expression was induced by high salt,drought,hypokalemia,ABA and H₂O₂. The results indicate that NtPOD1 belongs to tobacco peroxidase and may play a role in the response of tobacco to abiotic stress.

To seek new ways to improve the quality of tobacco, a field experiment was conducted to study the effect of vermicompost and vinasse on improving the growth and chemical properties of flue-cured tobacco using K326 as materials. Six treatments were set up, which were CK (conventional fertilization);T1(vermicompost 2 400 kg/ha);T2(vermicompost 1 800 kg/ha and vinasse 600 kg/ha);T3(vermicompost 1 200 kg/ha+vinasse 1 200 kg/ha);T4(vermicompost 600 kg/ha+vinasse 1 800 kg/ha);T5(vinasse 2 400 kg/ha),respectively. The results showed that vermicompost and vinasse could improve the plant growth, enhance the agronomic traits and chemical component of flue-cured tobacco, especially for the T2 (vermicompost 1 800 kg/ha and vinasse 600 kg/ha). The content of total nitrogen, total potassium and sugar content at topping stage were increased by 60.60%, 46.37% and 7.80%, while those at maturing stage were increased by 14.86%, 34.59%, 32.50%, as compared with CK, respectively. It also exhibited appropriate chemical property under T2 treatment. In conclusion, applying with vermicompost 1 800 kg/ha and vinasse 600 kg/ha can be suggested as a suitable fertilization models in tobacco-growing areas in Southern Shaanxi Province.

In order to reveal mechanism of internal injury on leaves under transplanting stage for flue-cured tobacco seedling. The changes of chlorophyll fluorescence kinetics curve of young and mature leaves were studied under high light and low temperature environment transferred from the weak light and mildness greenhouse through the methods of artificial simulation.The results showed that photosynthetic performance index (PI_ABS) in young leaves was lower significantly than that of mature leaves and the maximum photochemical efficiency of PS Ⅱ (Fv/Fm) was lower than that of mature leaves, but the difference between them was not significant.Especially, under the environment of high light and low temperature, the parameters of Fv/Fm and PI_ABS of young leaves reduction were significantly higher than the mature leaves, which indicated that young leaves were more likely to occuring inhibition phenomenon under high light and low temperature. The relative variable fluorescence (V_J and V_I) in young leaves were significantly higher than that of mature leaves, which suggested that electron transfer rate in PS Ⅱ receptor side of young leaves were significantly lower than the mature leaves. Under high lights and low-temperature, the increasing extend of V_J were significantly greater than mature leaves, the inhibition of electrons transfer from Q_A to Q_B in PS Ⅱreceptor under high light and low temperature.V_I increased amplitude of young leaves were relatively smaller than mature leaves under high light and low temperature, which indicated that the effects of electrons transfer from Q_B to PQ in young leaves were fewer under high light and low temperature, the electron transfer blocked sites in young leaves were still Q_A to Q_B transfer process. The relative variable fluorescence (V_K and V_L) of young leaves were significantly higher than that of mature leaves, under high light and low temperature, the values of V_K and V_L of young leaves raise were significantly higher than the mature leaves, which indicated that damaged degree in young leaves were more serious than mature leaves, which showed that high light and low temperature led to more damaged for oxygen evolving complex and thylakoid membrane structure in young leaves. Conclusion, damaged degree of young leaves PS Ⅱ function under high light and low temperature stress in transplanting stage were bigger than the mature leaf, which were relevant with photochemical activity, electron transfer rate and OEC in young seedlings leaves were sensitive to high light and low temperature.

The expression of the lectin gene (NTL1) from Narcissus tazzetta var. chinensis in Nicotiana alata was studied by qPCR method in order to determine the aphid-resistant function of NTL1 and cultivate N. alata with aphid-resistant. By means of susceptible to aphid,inoculation in vivo and in vitro,the resistance to aphid in different transgenic tobacco was studied. The result showed that NTL1 gene had been integrated into the tobacco,but the expression of different tobacco was different,the expression of NTL1 in tobacco by descending order was 3,4,1,2. The bioassay of aphid indicated that transgenic tobacco had a certain resistance to aphid,but the capacity of aphid-resistance in different tobacco plant was slightly different;The average density inhibition rate of aphid in inoculation in vivo and in vitro was 8.22%-76.61% and 4.62%-65.65%. The transgenic tobacco could speed up the aphid's death. The relative expression of NTL1 gene in different transgenic tobacco and the result of resistance to aphid were compared,showed that two results came with a high degree of consistency.