Teixeira M C, Coelho N, Olsson M E, Brodelius P E, Carvalho I S, Brodelius M
University of Algarve, Campus de Gambelas, Faro, 8005-139, Portugal.
Biotechnol Lett. 2009 Jul;31(7):1089-101. doi: 10.1007/s10529-009-9956-x. Epub 2009 Mar 10.
Two full-length cDNA clones of PoleFAD2 and one full-length cDNA clone of PoleFAD6, encoding omega-6 fatty acid desaturases, the key enzymes for the conversion of oleic into linoleic acid, were isolated from purslane (Portulaca oleracea L.) leaves and seeds. The deduced amino acid sequence of both isoforms of PoleFAD2 showed higher similarities to other microsomal omega-6 desaturases then to PoleFAD6 or other plastidial orthologues, and vice versa. Expression analysis by RT-PCR showed that all genes are expressed in all tissues of purslane tested, but higher levels of mRNA accumulation were detected in reproductive organs and cells that proliferate rapidly or store lipids. Wounding affected the levels of mRNA accumulation of both, FAD2 and FAD6 genes in purslane leaves, while chilling stress affected only FAD2 transcript level. The expression patterns observed reflect the discrete roles of these genes in membrane synthesis for cell division, thylakoid development, and lipid storage or in the biosynthetic pathway for the production of signaling molecules that influence plant development or defense.
从马齿苋（Portulaca oleracea L.）的叶片和种子中分离出了两个编码ω-6脂肪酸去饱和酶（将油酸转化为亚油酸的关键酶）的PoleFAD2全长cDNA克隆和一个PoleFAD6全长cDNA克隆。PoleFAD2两种同工型的推导氨基酸序列与其他微粒体ω-6去饱和酶的相似性高于与PoleFAD6或其他质体直系同源物的相似性，反之亦然。通过RT-PCR进行的表达分析表明，所有基因在所测试的马齿苋所有组织中均有表达，但在生殖器官以及快速增殖或储存脂质的细胞中检测到更高水平的mRNA积累。创伤影响马齿苋叶片中FAD2和FAD6基因的mRNA积累水平，而冷胁迫仅影响FAD2转录本水平。观察到的表达模式反映了这些基因在细胞分裂、类囊体发育和脂质储存的膜合成中，或在影响植物发育或防御的信号分子产生的生物合成途径中的不同作用。
