唐桂英 王芳 徐平丽 单雷

摘要：脂肪酸脱氢酶（FAD）能够调节膜脂中不饱和脂肪酸的水平来提高植物对不良环境的耐受性。本研究利用RT-PCR方法从花生中克隆到2个脂肪酸脱氢酶基因，命名为AhFAD2-2.1和AhFAD2-2.2。序列分析结果显示，2个基因的ORF区均为1 152 bp，编码383个氨基酸；cDNA水平上有12个碱基差异位点，其中只有483位和720位的碱基差异引起氨基酸的改变；它们的基因组序列大小分别为5 089 bp和5 090 bp，在5′UTR区分别存在一个3 821 bp和3 822 bp的内含子。qRT-PCR分析结果显示，这两个基因为组成型表达，其中在叶片中的表达量最高，花和根中次之，茎与种子中表达量最低。低温处理下，幼苗叶片中AhFAD2-2基因的表达量在0.5 h时迅速增加，至12 h达最高值，随后表达量逐渐下降，说明AhFAD2-2的表达响应低温胁迫诱导。本研究结果可为花生的抗寒性遗传改良提供理论依据。

关键词：花生（Arachis hypogaea L.）；AhFAD2-2基因；低温胁迫；基因表达

中图分类号：S565.2：Q781文献标识号：A文章编号：1001-4942（2018）06-0027-08

Abstract Fatty acid desaturase （FAD） can improve the stress tolerance of plants by regulating the contents of unsaturated fatty acids in membrane lipids. Two genes， named AhFAD2-2.1 and AhFAD2-2.2， encoding fatty acid desaturase were cloned from peanut by RT-PCR. Sequence analysis revealed that the ORF of both two genes were 1 152 bp， which encoded 383 amino acids. There were 12 different nucleotides between the two cDNA squences， among which， only the sites located at 483 and 720 lead to the differences at amino acid level. The gDNA sizes of the two genes were 5 089 bp and 5 090 bp， respectively. One 3 821-bp intron and one 3 822-bp intron were identified in the 5′UTR region of AhFAD2-2.1 and AhFAD2-2.2. The result of qRT-PCR showed that AhFAD2-2 was constitutively expressed， and the expression level was the highest in leaves， followed by flowers and roots， and the lowest in seeds. Under the low-temperature treatment， the expression level of AhFAD2-2 in peanut leaves increased significantly at 0.5 hour， reached the peak at 12 hour， and then decreased gradually. The results indicated that AhFAD2-2 might be responded to low temperature in peanut. This study could provide theoretical bases for the genetic improvement of cold resistance in peanut.

Keywords Peanut （Arachis hypogaea L.）； AhFAD2-2 gene； Low-temperature stress； Gene expression

低溫是限制植物分布，影响植物生长发育的重要因素。当环境温度降低至不适宜植物生长的程度时，植物细胞中的不饱和脂肪酸含量及其组成会发生改变，以维持细胞膜的流动性和稳定性，降低逆境对膜结构的损害，增强植物抗寒性[1，2]。因此，研究植物细胞中不饱和脂肪酸的代谢，对于阐明植物的抗寒机制具有重要意义。

FAD2（fatty acid desatuase 2）是一种定位在内质网中的Δ-12去饱和酶[3-5]，主要功能是催化单价不饱和脂肪酸C18∶1Δ9（油酸）在C12位脱氢，生成二价不饱和脂肪酸C18∶2Δ9，12（亚油酸）。大多数高等植物叶细胞中亚油酸（C18∶2Δ9，12）和亚麻酸（C18∶3Δ9，12，15）含量占脂肪酸总量的70%以上，非光合组织根与种子中所占比例也较高。……