天山雪莲SiSAD基因与拟南芥AtFAB2基因转化烟草的抗寒性分析

通过转基因烟草(Nicotiana tabacum)验证天山雪莲(Saussurea involucrata)?9硬脂酰-ACP脱饱和酶基因Si SAD与拟南芥(Arabidopsis thaliana)中同源基因At FAB2的抗寒性功能。利用农杆菌介导法将植物表达载体PSi SAD:At FAB2和PSi SAD:Si SAD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(Fv/Fm)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Si SAD基因烟草的恢复效果显著优于转At FAB2基因和野生型烟草。在0°C和-2°C处理2小时后,转Si SAD、At FAB2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Si SAD、At FAB2基因型烟草的Fv/Fm显著高于野生型烟草,其中,转Si SAD基因烟草的Fv/Fm显著高于转At FAB2基因烟草。转At FAB2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Si SAD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At FAB2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?9硬脂酰-ACP脱饱和酶基因Si SAD与拟南芥中同源基因At FAB2均可以显著增强非低温驯化烟草的抗寒性,但是Si SAD基因效果显著优于At FAB2。

Cold-tolerance Analysis of Tobacco Plants Transformed with Saussurea involucrata SiSAD and Arabidopsis thaliana AtFAB2 Gene

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.