通过大田试验, 研究了不同氮素形态及配比对烤烟叶片中谷酰胺合成酶(GS)、蔗糖合成酶(SS)、蔗糖磷酸合成酶(SPS)活性及烟碱、还原糖含量的影响、结果表明, 在移栽后85 d至采收结束, 1’2(纯施NH4-N)烟叶中的GS和SPS一直保持相对较高的水平；在移栽后91 d, 其烟碱含量是T1(纯施NO3-N)的1.2倍、13(NO3-N：NH4-N的质量比为1: 1)的1.1倍。还原糖含量是T1的0.4倍、13的0.6倍、T1有利于还原糖的积累；13有利于碳氮代谢的协调进行、

目的：选择不同的分离、纯化步骤并比对分析，筛选出纯化烟草中多酚氧化酶(PPO)的优化组合方案。方法：采用分段盐析、DEAE-Sephamse Fastflow和Sephadex G-150柱层析纯化PPO，通过测定和比较酶活性筛选最佳条件。结果：确定了最佳盐析浓度 (40％) 和柱层析条件，SDS-PAGE、FPIC以及动力学常数的检测结果表明，纯化出的蛋白质相对分子质量为42 000, Km为1.2 mmol/L，得到了纯化9l倍的烟草多酚氧化酶Ⅱ。结论：优化方案减少了有机溶剂分级沉淀、阳离子交换层析等步骤，使纯化过程大大缩短。

The biological properties on tobacco with 35S: BnDREB1-5 transformation were analyzed which included the holding water capacity, the size and density of upper and lower epidermis stomata, the content of chlorophyll, and plasma membranes permeability after physical drought stressed 7h. The results indicated that water-holding capacity of 35S: BnDREB1-5 transgenic tobacco leaves was 62% higher than wild-types. The upper epidermis stomata apparatus was bigger in transgenic tobacco than wild-type, but the opening of stoma was smaller in upper epidermis than wild-types. The stomata density was 1. 5 times in wild-type leaves as large as in transgenic leaves. The content of chlorophyll was 29% higher in leaves of wild-type than in transgenic leaves, and the plasma membranes permeability were 1. 4 times in wild-type leaves as large as in transgenic tobacco.

Four AP2/EREBP genes encoding putative ethyleneresponsive element binding factor (ERF)/AP2 domains were cloned from Brassica napus, and these genes could be induced by low temperature, ethylene, drought, high salinity, abscisic acid and jasmonate treatments. These four genes, named BnDREBIII-1 to BnDREBIII-4, were highly homologous and the 37th amino acid was the only difference among their ERF/AP2 domains. BnDREBIII-1 was demonstrated to be able to bind to both dehydration-responsive element and the GCC box and transactivate the expression of downstream genes, while BnDREBIII-4 could bind neither. Further results suggested that Ala37 might play a crucial role in the DNA binding or the stability of the ERF/AP2 domain.

Net photosynthetic rate (PN) of tobacco plants grown with NH4-N as the only N source was the lowest all the times, while PN grown only with NO3-N was the greatest until 22nd day, and PN grown with both NO3-N and NH4-N (1: 1) was the greatest. Maximal photochemical efficiency of photosystem 2 (PS2), Fv/Fm, and actual quantum yield of PS2 under actinic irradiation (ΦPS2) in plants grown with only NH4-N were greatest at early stage and then decreased and were smaller than those of other treatments. Photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (qNP) in the NH4-N plants were the greatest at all times. Hence excessive NH4-N can decrease not only photochemical efficiency but also the efficiency of utilization of photon energy absorbed by pigments for photosynthesis. Therefore, excessive NH4-N is a hindrance to photosynthesis of flue-cured tobacco. On the other hand, tobacco cultured with an appropriate mixture of NO3-N with NH4-N can sufficiently utilize photon energy and increase the efficiency of energy transformation.