外源MeJA对低温下紫苏脂肪酸合成及FAD3基因表达的调控

Effects of exogenous MeJA on the regulation of fatty acid synthesis and FAD3 gene expression in Perilla frutescens under low temperature

[目的]茉莉酸甲酯(MeJA)是调节植物应激反应的天然植物生长调节物质,探讨其对低温胁迫下紫苏幼苗抗冷性的影响,为紫苏抗逆机制的研究提供理论依据。[方法]以紫苏品种"晋紫苏1号"为试验材料,在其长出4片真叶后分别进行4℃低温胁迫和0.025mmol·L^(-1 )MeJA+4℃低温胁迫处理,分析处理0、3、6、9、12、24h后紫苏幼苗叶片中脂肪酸组分及含量、相对电导率、丙二醛含量以及ω-3脂肪酸脱氢酶基因(FAD3)的相对表达量。[结果]MeJA+4℃处理后,不饱和脂肪酸C18∶3的含量急剧上升,处理6h时为对照的6.96倍,且不同处理条件下,紫苏叶片总脂肪酸含量均显著上升;经外源MeJA处理后,随着低温胁迫时间的延长,相对电导率和MDA含量都比4℃胁迫处理时显著降低;MeJA+4℃胁迫处理3h时FAD3基因的表达量达到最高,为对照的15.9倍。[结论]在外源MeJA协同低温处理下,诱导FAD3基因高量表达,不饱和脂肪酸含量增加,紫苏细胞膜完整性较好,幼苗抗冷性增强。

[Objectives] Methyl jasmonate (MeJA) is a natural plant growth regulator which profoundly modifies plant stress response. In this paper, the effect of exogenous MeJA on the cold resistance of perilla seedlings was investigated, and aimed to provide a theoretical basis for the study of the resistance mechanism of perilla.[Methods] The perilla variety,"Jinzisu 1″, was employed as the experimental material, and perilla seedlings were treated with 0.025 mmol ·L^-1 MeJA for 0, 3, 6, 9, 12, and 24 h at 4℃. The ones without MeJA treatment served as the control group at the same temperature. The fatty acid composition and content, relative electrical conductivity, the content of malondialdehyde, and relative expression levels of the omega-3 fatty acid dehydrogenase gene ( FAD3 ) in the seedling leaves of each treatment were measured.[Results] The content of unsaturated fatty acid C18:3 was increased dramatically when plants were treated with MeJA at 4℃, and it was peaked at 6 h post treatment with 6.96 times higher concentration than that of the control. The total fatty acid content in perilla leaves was increased significantly in all different treatments. The relative electrical conductivity and MDA content were decreased significantly with the prolongation of low temperature stress plus MeJA treatments. The relative expression level of FAD3 gene of MeJA treatment was peaked at 3 h post treatment, which was 15.9 times higher than that of the control.[Conclusion] Under the condition of exogenous MeJA combined with low temperature, high expression of FAD3 gene in perilla seedlings was induced and the content of unsaturated fatty acids was increased. Besides, the perilla cell membrane integrity could be better maintained and the cold resistance of seedlings was enhanced.