The plastidial delta-12 fatty acid desaturase (FAD6) plays a key role in linoleic acid (LA) and α-linolenic acid (ALA) biosynthesis. Perilla (Perilla frutescens) is an important oilseed crop with the highest ALA level. Here, using RACE PCR, two FAD6 cDNAs were cloned from perilla: the 1726 bp PfFAD6 and the 1881 bp PfFAD6’. PfFAD6 encodes a 443 aa protein, while PfFAD6’ is a pseudogene caused by premature stop codon mutation. N-terminal of PfFAD6 has a chloroplast transit peptide. PfFAD6 harbors an omega-6 FAD conserved domain, 2 trans-membrane helices and 3 histidine boxes. Phylogenetic analysis revealed some important evolutionary features of PfFAD6 and other plant FAD6 genes. Heterologous yeast expression showed that protein encoded by PfFAD6 can catalyze the production of LA. PfFAD6 was expressed in various organs at different levels, and responded to multiple biotic/abiotic stresses. The qRT-PCR assay and fluorescence imaging showed the correlation of PfFAD6 transcripts and photosynthetic activity under Sclerotinia infection. This study will lay a foundation for further function study of PfFAD6 in quality improvement in oilseed crops and plant-stress response.

质体 delta-12 脂肪酸去饱和酶 (FAD6) 在亚油酸 (LA) 和 α-亚麻酸 (ALA) 生物合成中起关键作用。紫苏（Perilla frutescens）是一种重要的油料作物，ALA含量最高。在这里，使用 RACE PCR，从紫苏中克隆了两个FAD6 cDNA：1726 bp PfFAD6和 1881 bp PfFAD6'。PfFAD6编码一个 443 aa 的蛋白质，而PfFAD6'是由过早终止密码子突变引起的假基因。PfFAD6 的 N 端有一个叶绿体转运肽。PfFAD6 包含一个 omega-6 FAD 保守结构域、2 个跨膜螺旋和 3 个组氨酸盒。系统发育分析揭示了PfFAD6 的一些重要进化特征和其他植物FAD6基因。异源酵母表达表明PfFAD6编码的蛋白质可以催化 LA 的产生。PfFAD6在各种器官中以不同水平表达，并对多种生物/非生物胁迫作出反应。qRT-PCR 测定和荧光成像显示PfFAD6转录物与菌核感染下光合活性的相关性。本研究将为进一步研究PfFAD6在油料作物品质改良和植物逆境响应中的作用奠定基础。