烟草转化株烟碱含量对其向降烟碱转化程度的影响

Impact of nicotine content on the conversion level of nicotine to nornicotine in converter tobacco plants

在烟株生长早期鉴别转化株,需要对转化株的烟碱转化进行诱导以使转化性状充分表达,但同一基因型材料在不同生长条件 下经诱导产生的烟碱转化程度存在较大差异。本试验旨在探讨转化株的烟碱基础含量对诱导后烟碱转化程度的影响。结果表明由 于打顶和增施氮肥造成烟碱基础含量增高可显著降低诱导后的烟碱转化程度。在温室条件下,通过调节氮肥施用量获得具有不同 烟碱含量的植株,以白肋烟TN90的高转化品系为材料的试验表明,当烟碱基础含量超过2.0%时,烟碱向降烟碱转化不完全,随着 烟碱含量的增高,烟碱转化百分率几乎呈线形下降。采用由高转化系和非转化系杂交的F1植株为材料进行试验,发现烟碱转化百 分率随烟碱含量下降的趋势更加明显。采用低转化株的自交分离后代进行试验,发现在低施氮水平下对转化株进行诱导和鉴别的 有效性高于在高施氮条件下对转化株的诱导和鉴别。因此,使烟株维持较低的烟碱水平有利于转化株特别是低转化株的有效鉴别。

In the process of screening for nicotine to nornicotine converter plants at early plant growth stage, the stimulation of nicotine conversion is required to let the conversion trait display. It has been noticed that after stimulation the conversion level of the same genotype varies greatly under different conditions. The experiments were set up to investigate the cause of this variation. Results indicated that high nicotine level resulting from topping and high nitrogen fertilizer application significantly reduce the degree of conversion after stimulation. Different nicotine levels were achieved by using different amount of nitrogen fertilizer in greenhouse. In TN90 high converter line, when nicotine content in a leaf is greater than 2.0%, the conversion of nicotine to nornicotine after stimulation became incomplete, and as the nicotine level increased, the conversion degree decreased almost linearly. The trend is more obvious when using the F1 hybrid crossing from high converter line and non-converter line. This hybrid had lower conversion potential. Experiments with segregated generation which contain a great proportion of minor converters showed that when nicotine level in a leaf is greater than 2%, the minor converters could hardly be identified after stimulation. Therefore, maintaining lower nicotine level is very important in ensuring effective identification of converters, especially of minor ones.