通过转基因烟草(Nicotiana tabacum)验证天山雪莲(Saussurea involucrata) Δ9硬脂酰-ACP脱饱和酶基因SiSAD与拟南芥(Arabidopsis thaliana)中同源基因AtFAB2的抗寒性功能。利用农杆菌介导法将植物表达载体P_SiSAD:AtFAB2和P_SiSAD:SiSAD导入烟草, 然后将2种转基因和野生型烟草分别置于20°C、10°C、5°C、0°C及-2°C下处理2小时, 检测其相对电导率、丙二醛(MDA)含量、叶绿素荧光参数(F_v/F_m)及脂肪酸含量。将-2°C处理2小时后的植株置于25°C培养1周进行生长恢复实验。结果表明, 生长恢复实验中转SiSAD基因烟草的恢复效果显著优于转AtFAB2基因和野生型烟草。在0°C和-2°C处理2小时后, 转SiSAD、AtFAB2基因型和野生型烟草的相对电导率和丙二醛含量呈现显著递增趋势; 转SiSAD、AtFAB2基因型烟草的F_v/F_m显著高于野生型烟草, 其中, 转SiSAD基因烟草的F_v/F_m显著高于转AtFAB2基因烟草。转AtFAB2基因型和野生型烟草的油酸(C18:1)含量随着温度的降低逐渐升高后降低并在0°C时达到最高值; 而转SiSAD基因型烟草C18:1含量持续升高, 并在-2°C时达到最高值, 其含量分别是转AtFAB2基因型和野生型烟草的1.58倍和1.7倍。以上结果表明, 天山雪莲Δ9硬脂酰-ACP脱饱和酶基因SiSAD与拟南芥中同源基因AtFAB2均可以显著增强非低温驯化烟草的抗寒性, 但是SiSAD基因效果显著优于AtFAB2。

The SiSAD gene in Saussurea involucrata and its homologous gene AtFAB2 in Arabidopsis thaliana have been reported to encode homeologous Δ9 stearoyl-acp desaturases. To investigate the function of these genes in plants’ response to cold stress, we constructed two expression vectors PSiSAD:AtFAB2 and PSiSAD:SiSAD, and were Agrobacterium-infiltrated in tobacco. These two kinds of transgenic plants and wild-type tobacco were treated at 20°C, 10°C, 5°C, 0°C, and -2°C for 2 h and then to determine the relative conductivity, malondialdehyde (MDA) and fatty acid content and chlorophyll fluorescence parameters (F_v/F_m). Furthermore, after -2°C treatment for 2 h, and recovery at 25°C for 1 week, we examined recovery rate of these tobacco plants. The recovery rate of SiSAD transgenic tobacco was much better than AtFAB2 transgenic tobacco and wild type. After treatment at 0°C and -2°C for 2 h, the relative conductivity and MDA content of the SiSAD and AtFAB2 transgenic tobacco and wild-type tobacco showed a significant increasing trend. The F_v/F_m of SiSAD and AtFAB2 transgenic tobacco were significantly higher than wild-type tobacco and the F_v/F_m of SiSAD transgenic tobacco was significantly higher than AtFAB2 transgenic tobacco. The content of oleic acid (C18:1) in AtFAB2 transgenic tobacco and wild type were decreased gradually with decreasing temperature and reached the lowest level at 0°C, whereas the content of C18:1 in SiSAD transgenic tobacco increased and peaked at -2°C; The C18:1 contents in SiSAD transgenic tobacco were at least 1.58 and 1.7 folds when compared to AtFAB2 transgenic tobacco and wild type. These results indicate that SiSAD and AtFAB2 genes can significantly enhance the cold tolerance of a non-cold acclimated tobacco. Moreover, the SiSAD gene plays more important role than AtFAB2 gene in cold tolerance.