超量表达NrCN烟草光合特征及烟叶化学成分分析

Photosynthetic characteristics and chemical compositions of transgenic tobacco with overexpressed Nr CN

为明确TMV抗性基因NrCN对转基因烟草光合特性及烟叶化学成分的影响,在人工培养箱和温室条件下以含有Pubi.u4::NrCN表达元件的T2代转基因烟草植株为材料,分析了不同转基因烟草株系应答TMV感染时NrCN的表达量、转基因烟草化学成分含量(质量分数),以及烟草光合作用指标的差异。结果表明,转基因株系Q2对TMV抗性最强,表现为TMV感染后NrCN基因的表达量最高,叶片可形成明显的坏死斑,Q1株系次之。烟叶化学成分测定结果表明,Q2植株打顶前后总植物碱和总氮含量均显著(P<0.05)低于其他两个转基因(Q1、Q3)和非转基因植株;而打顶前后Q2株系中氯离子积累较多。另外,打顶前非转基因植株的可溶性糖含量(14.82mg·g^-1)极显著(P<0.01)低于转基因Q1株系(21.88mg·g^-1)和Q2株系(16.85mg·g^-1)。光合指标测定结果显示,NrCN基因的导入使转基因烟草的光合作用指标发生了不同程度改变,其中Q1株系在低光强(1000μmol·m^-2·s^-1)时其净光合速率(Pn)、气孔导度(Gs)和蒸腾速率(Tr)等指标均显著提高。因此Q1株系可作为培育抗TMV烟草新种质的理想亲本材料。

In order to clarify the effects of TMV-resistance gene NrCN on photosynthesis and chemical components of transgenic tobacco, T2 transgenic tobacco plants containing Pubi.u4::NrCN in the conditions of artificial climate incubators and greenhouse were used as research samples to determine the differential NrCN expression level, chemical compositions and photosynthetic characteristics in transgenic plants. The results showed that transgenic line Q2 with the strongest TMV resistance had the highest NrCN expression level and obvious lesions in leaves. In addition, transgenic line Q1 was stronger. The leaf chemical results indicated that the contents of total alkaloid and total nitrogen in Q2 line before and after topping were significantly lower than those of Q1 and Q3 lines, also lower than the non-transgenic line (P<0.05). However, chloride ion accumulation in Q2 line was higher before and after topping. The soluble sugar content (14.82 mg·g^-1) in non-transgenic line before topping was significantly (P<0.01) lower than that in Q1 (21.88 mg·g^-1) and Q2 lines (16.85 mg·g^-1), respectively. Introducing NrCN gene could change the photosynthetic indexes of transgenic tobacco to different extents. Under a low light intensity (1 000 μmol·m^-2·s^-1), the net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of Q1 line increased significantly. Therefore, Q1 line could be used as an ideal parent material for breeding new tobacco germplasms with TMV resistance.