应用FTIR研究模式植物拟南芥和烟草甲醛代谢机理的差异

运用FTIR技术分析模式植物拟南芥和烟草在甲醛胁迫条件下体内各物质含量的变化规律及光谱表征，为推定两种植物甲醛代谢机理的差异提供线索。拟南芥红外光谱中1 376 cm-1的纤维素峰没有出现在烟草样品中。在应对甲醛胁迫时，它的强度值下降趋势比其他吸收峰小，说明拟南芥体内的甲醛主要流向氧化生成甲酸和CO₂的途径。胁迫后期该吸收峰强度值下降，而其他物质的峰持续上升，说明该途径中相关酶基因的表达可能受到甲醛抑制，而其他途径的酶基因表达不受影响。烟草用甲醛处理后红外光谱中各化学成分的含量变化趋势一致，说明甲醛进入各代谢途径的流量差别不大。第4天时烟草红外光谱各吸收峰的强度值再次下降是其甲醛代谢能力较弱结果，表明烟草对甲醛的抗性不如拟南芥强。

Investigation on the Difference in HCHO Metabolic Mechanism between Arabidopsis and Tobacco Using FTIR

In the present study, the model plants, arabidopsis and tobacco, were chosen for FTIR analysis to investigate the spectrum characters and the changes in their chemical component contents in the time course of HCHO treatment, providing clues to explain the difference in HCHO metabolic mechanism between the two plants. The FTIR data showed that all the chemical components of arabidopsis and tobacco varied under HCHO stress conditions. An interested peak near 1 376 cm-1 which was assigned as the absorption of methyl group of cellulose was specially existed in the spectrum of arabidopsis. This peak showed a mild decrease compared with other peaks at the beginning (at 1 day) of HCHO stress. This indicated that the major part of HCHO metabolic flux was introduced towards its oxidation pathway to form HCOOH and CO₂ subsequently and only small amount of HCHO entered the other pathways. The CO₂ was assimilated in Calvin cycle to form sugars which might be used to synthesis of cellulose later. At 7 day of HCHO treatment, the height of the peak decreased whereas the height of the other peaks still increased. This might suggest that the gene expression of some enzymes in the HCHO oxidation pathway was inhibited under HCHO stress conditions and the inhibition might not happen to the gene expression of the enzymes in other pathways. In the case of tobacco, the contents of all chemical components showed the same variation on the FTIR spectrum in the time course of HCHO treatment, which indicated that there was no much difference in HCHO metabolism flux in each pathway. At 4 day of HCHO treatment, the decrease in the height of all peaks is the result of the poor ability of HCHO metabolism of tobacco, which also demonstrated the lower HCHO tolerance of tobacco compared with arabidopsis.