Yaeno Takashi, Saito Bunnai, Katsuki Tsutomu, Iba Koh
Department of Biology, Faculty of Sciences, Kyushu University, Hakozaki, Fukuoka, Japan.
Plant Cell Physiol. 2006 Mar;47(3):355-62. doi: 10.1093/pcp/pci253. Epub 2006 Jan 13.
The Arabidopsis FAD7 gene encodes a plastid omega-3 fatty acid desaturase that catalyzes the desaturation of dienoic fatty acids to trienoic fatty acids in chloroplast membrane lipids. The expression of FAD7 was rapidly and locally induced by ozone exposure, which causes oxidative responses equivalent to pathogen-induced hypersensitive responses and subsequently activates various defense-related genes. This induction was reduced in salicylic acid (SA)-deficient NahG plants expressing SA hydroxylase, but was unaffected in etr1 and jar1 mutants, which are insensitive to ethylene and jasmonic acid (JA), respectively. The SA dependence of the FAD7 induction was confirmed by the exogenous application of SA. SA-induced expression of FAD7 in the npr1 mutant which is defective in an SA signaling pathway occurred to the same extent as in the wild type. Furthermore, in the sid2 mutant which lacks an enzyme required for SA biosynthesis, the expression of FAD7 was induced by ozone exposure. These results suggest that the ozone-induced expression of FAD7 gene requires SA, but not ethylene, JA, NPR1 and SID2.
拟南芥FAD7基因编码一种质体ω-3脂肪酸去饱和酶，该酶催化叶绿体膜脂中双烯脂肪酸去饱和形成三烯脂肪酸。臭氧暴露可快速且局部地诱导FAD7的表达，臭氧暴露会引发与病原体诱导的超敏反应相当的氧化反应，并随后激活各种防御相关基因。在表达水杨酸（SA）羟化酶的SA缺陷型NahG植物中，这种诱导作用减弱，但在分别对乙烯和茉莉酸（JA）不敏感的etr1和jar1突变体中不受影响。通过外源施用SA证实了FAD7诱导对SA的依赖性。在SA信号通路有缺陷的npr1突变体中，SA诱导的FAD7表达与野生型中发生的程度相同。此外，在缺乏SA生物合成所需酶的sid2突变体中，FAD7的表达也受到臭氧暴露的诱导。这些结果表明，臭氧诱导的FAD7基因表达需要SA，但不需要乙烯、JA、NPR1和SID2。
